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Protein level in the haemolymph of the wasp Polistes gallicus L. at the beginning of imaginal life and during overwintering. Action of the strepsiterian parasite Xenos vesparum rossi
Abstract
Summary During the imaginal life of malePolistes wasps, the protein concentration in the haemolymph remained constant. In females, there were 2 groups; one in which this concentration was also stable and another in which it increased. No difference was detected between the haemolymphatic protein level of stylopized males and normal ones. All parasitized females exhibited low haemolymph protein levels similar to those of the low level group.
... Morpho-physiological changes induced by the parasite in the female wasp include smaller body size, higher fluctuating asymmetry, less broken facial pattern (Cervo et al. 2008;Beani et al. 2011;Tibbetts et al. 2011) and, above all, castration. Regardless of the putative caste, parasitized females show undeveloped ovaries, reduced volume of corpora allata and lowered levels of juvenile hormone (Strambi and Strambi, 1973;Strambi et al. 1982;Beani et al. 2011). However, very little attention has been given to the parasitic impact on the male phenotype of P. dominula, with the exception of a study that reports a different effect of the parasite on haemolymph protein levels in male wasps compared with females (Strambi et al. 1982). ...
... Regardless of the putative caste, parasitized females show undeveloped ovaries, reduced volume of corpora allata and lowered levels of juvenile hormone (Strambi and Strambi, 1973;Strambi et al. 1982;Beani et al. 2011). However, very little attention has been given to the parasitic impact on the male phenotype of P. dominula, with the exception of a study that reports a different effect of the parasite on haemolymph protein levels in male wasps compared with females (Strambi et al. 1982). ...
... Since our parasitized males were collected on leks, there might be a bias towards those males capable of tolerating the infection; nonetheless, it is still remarkable that at least a segment of the male population is not affected either in behaviour or in morphology, whereas parasitized females are always dramatically affected by X. vesparum, regardless of parasite load and sex. Despite the controversy about the male as 'the sicker sex' (Zuk, 1990(Zuk, , 2009 and the current lack of physiological data about the pathological changes induced by parasites in male insects (for a review in invertebrates see Schmid-Hempel, 2011;Retschnig et al. 2014), we can hypothesize that neuroendocrine alterations are induced by X. vesparum in female but not male hosts (Strambi and Strambi, 1973;Strambi et al. 1982). Further investigations are necessary to assess the proximate mechanism responsible for the different phenotype alterations shown by P. dominula sexes. ...
SUMMARY Host castration represents a mechanism used by parasites to exploit energy resources from their hosts by interfering with their reproductive development or to extend host lifespan by removing risks associated with reproductive activity. One of the most intriguing groups of parasitic castrators is represented by the insects belonging to the order Strepsiptera. The macroparasite Xenos vesparum can produce dramatic phenotypic alterations in its host, the paper wasp Polistes dominula. Parasitized female wasps have undeveloped ovaries and desert the colony without performing any social task. However, very little attention has been given to the parasitic impact of X. vesparum on the male phenotype. Here, we investigated the effects of this parasite on the sexual behaviour and the morpho-physiology of P. dominula males. We found that, differently from female wasps, parasitized males are not heavily affected by Xenos: they maintain their sexual behaviour and ability to discriminate between female castes. Furthermore, the structure of their reproductive apparatus is not compromised by the parasite. We think that our results, demonstrating that the definition of X. vesparum as a parasitoid does not apply to infected males of P. dominula, provide a new perspective to discuss and maybe reconsider the traditional view of strepsipteran parasites.
... They are parasitic castrators (sensu Baudoin 1975), that is, regardless of the parasite load, stylopized Polistes develop filiform ovaries if female and do not develop testes if male (preliminary data in Beani et al. 2004b). Changes in haemolymph proteins do not compromise wasp longevity (Strambi et al. 1982), as would be expected in case of parasitic castration: "by attacking non-vital organs, castrators do not reduce the host life span, and they can obtain a high transmission rate without trading off longevity" (Poulin 1998). If resource allocation shifts from reproductive organs to energy reserves, the hosts become efficient vehicles for parasite survival and transmission. ...
... Finally, data show a very low rate of drones (2% or less) in summer aggregations. Due to the entry of triungulins in wasp larvae of both sexes, and the successful emergence of stylopized males in lab (Strambi et al. 1982, L. Beani pers. obs.), the most parsimoni-ous explanation for this female-biased sex-ratio is that the main target of triungulins are workers rather than sexuals (at least in our study population and species; but see Dunkle [1979] for stylopized sexuals in P. annularis). ...
... But many chapters of this story are still obscure. Some of the unexplored topics in the Xenos-Polistes system relate to the physiological basis of host behavioural changes (after the excellent pioneer studies by , Strambi et al. [1982]), to changes at the level of epicuticular hydrocarbons, venom volatiles of stylopized wasps and further chemical cues (see , Bruschini et al 2005, Dapporto et al. 2006, to the intimate relationship between the parasite and the host's immune system, to analysis of the "horizontal transmission" of parasites from one social insect colony to another (see Hughes 2005), and finally to the impact of strepsipterans in North America populations of P. dominulus, a recent invasive species (Pickett & Wenzel 2000, Liebert et al. 2006. ...
The infection of Polistes dominulus wasps by the strepsipteran Xenos vesparum provides a suitable case study for exploring parasitic manipulation. One aim of this review is to summarize the life cycle of X. vesparum: from infection of immature wasps to the "stylopization" of adults, and from its mating at summer aberrant aggregations of infected wasps to the overwintering of fertilized Xenos inside the abdomen of hibernating wasps. The second aim of this review it to highlight how this parasite manipulates the flexible phenotype of the wasp to maximize its own reproductive success.
... In this view, it could be advantageous for Polistes foundresses to exit the overwintering period with characteristics typical of dominant individuals, in order to increase the probability of winning the first agonistic interactions. Indeed, physiological differences among foundresses seem to be present before nest foundation (Strambi et al. 1982(Strambi et al. , Röseler et al. 1984(Strambi et al. , 1985. Strambi et al. (1982) demonstrated that P. dominulus females differed during overwintering in their haemolymph protein concentration. ...
... Indeed, physiological differences among foundresses seem to be present before nest foundation (Strambi et al. 1982(Strambi et al. , Röseler et al. 1984(Strambi et al. , 1985. Strambi et al. (1982) demonstrated that P. dominulus females differed during overwintering in their haemolymph protein concentration. In particular, females affected by the strepsipteran parasite Xenos vesparum exhibited low protein level in haemolymph. ...
... The same low levels were found in several females that were not affected by the parasite. Such differentiation in protein levels was not determined at a pre-imaginal stage, as these differences became evident 10 days after emergence (Strambi et al. 1982). ...
Dapporto, L. & Palagi, E. 2006: Wasps in the shadow: Looking at the pre-hibernating clusters of Polistes dominulus. — Ann. Zool. Fennici 43: 583–594. In some Polistes species, hibernation begins with the formation of clusters. Pre-hiber-nating aggregations may be evolutionarily favoured because they provide a dilution effect, better active defence from predators, and insulation from cold and/or dryness. Many authors have suggested that the pre-hibernating phase represents a socially inac-tive period for wasps. This paradigm strongly influenced the direction of research; in fact, most studies on Polistes behaviour focus on the nesting phase. It has been demonstrated, however, that many social interactions occur in aggregations, and that a division of labour is also present in these aggregations. Here, we evaluate the influence of cluster formation and social networks on the main aspects of wasp social behaviour, such as the consequences on kin-assortment (philopatry and tolerance level), variation in chemical recognition, division of labour, and helping behaviour.
... After metamorphosis, adult female parasites remain as obligate endoparasites inside the host, while adult males emerge from the host, and mate with females. Parasite pupae decrease the size of corpora allata in female hosts and castrate them by irreversibly inhibiting ovary development (Strambi and Strambi, 1973;Strambi et al., 1982;Hughes et al., 2004b;Beani, 2006). Parasitized workers abandon the colony and aggregate on selected plants where parasite mating occurs (Hughes et al., 2004b;Beani et al., 2018). ...
... Previous work has shown that X. vesparum drives gene expression changes of workers toward a gyne-like pattern; thus, the parasite is manipulating the transcriptomic plasticity of the caste system (Geffre et al., 2017). Parasitized females also show low levels of haemolymphatic protein and juvenile hormone compared to non-parasitized females, but with no difference between non-parasitized and parasitized males (Strambi and Strambi, 1973;Strambi et al., 1982). Our study shows that strepsipteran do not drive evident neuroanatomical changes in their females hosts, suggesting that this parasite may be relying on other manipulation mechanisms . ...
Brain plasticity is widespread in nature, as it enables adaptive responses to sensory demands associated with novel stimuli, environmental changes and social conditions. Social Hymenoptera are particularly well-suited to study neuroplasticity, because the division of labor amongst females and the different life histories of males and females are associated with specific sensory needs. Here, we take advantage of the social wasp Polistes dominula to explore if brain plasticity is influenced by caste and sex, and the exploitation by the strepsipteran parasite Xenos vesparum. Within sexes, male wasps had proportionally larger optic lobes, while females had larger antennal lobes, which is consistent with the sensory needs of sex-specific life histories. Within castes, reproductive females had larger mushroom body calyces, as predicted by their sensory needs for extensive within-colony interactions and winter aggregations, than workers who frequently forage for nest material and prey. Parasites had different effects on female and male hosts. Contrary to our predictions, female workers were castrated and behaviorally manipulated by female or male parasites, but only showed moderate differences in brain tissue allocation compared to non-parasitized workers. Parasitized males maintained their reproductive apparatus and sexual behavior. However, they had smaller brains and larger sensory brain regions than non-parasitized males. Our findings confirm that caste and sex mediate brain plasticity in P. dominula, and that parasitic manipulation drives differential allocation of brain regions depending on host sex.
... Among them, Xenos vesparum (Xenidae, Strepsiptera) is of particular interest. X. vesparum is closely associated with the social wasp Polistes dominula (Hughes et al., 2004;Beani, 2006), and while having a dramatic impact on the phenotype of the female hosts (Beani et al., 2011), including castration (Strambi et al., 1982;Kathirithamby, 2009;Beani et al., 2011), it has a less understood effect on the male host phenotype, in terms of sexual behaviour and morphology of the reproductive apparatus . ...
... Interestingly, parasitism by X. vesparum disrupts JH-secreting CA in female wasps and consequently castrates the female host (Röseler et al., 1980), regardless of parasite load and sex (Beani et al., 2011). Female wasps are irreversibly castrated due to the early CA inhibition, since parasite removal from adult females does not restore the host normal reproductive physiology (Strambi and Girardie, 1973;Strambi et al., 1982). Conversely, X. vesparum does not impact the JH pathway in male hosts and this could be one mechanism by which male hosts maintain their sexual maturation and activity. ...
Parasitic castration is an adaptive strategy where parasites usurp the hosts’ reproductive physiology to complete their life cycle. The alterations in the host traits vary in their magnitude, from subtle changes in the host morpho-physiology and behaviour to the production of complex aberrant phenotypes, which often depend on the host gender. The strepsipteran macroparasite Xenos vesparum induces dramatic behavioural and physiological changes in its female host, the paper wasp Polistes dominula, while its effect on the male phenotype is largely unknown.
... Parasites alter host behaviour by a diversity of mechanisms (Thompson & Kavaliers 1994), and the physiological pathways by which parasitic castration is translated into changes in host behaviour are poorly known (Hurd 1993). Some authors have suggested that parasitic castrators divert energy and nutrients away from host reproduction into parasite growth and reproduction (Strambi et al. 1982 ;Hurd 1993). In this sense, the behavioural physiology of parasitic castration may resemble intrinsic (nonparasitic) caste determination mechanisms in social insects, which frequently involve nutritional differences among individuals (Wheeler 1986 ;Hunt 1991). ...
... Parasitic nematodes frequently reduce fecundity of insect hosts via effects on the fat body and\or corpora allata (site of JH production), implying endocrine disruption (Wu$ lker 1975). Longevity of strepsipteran hosts is rarely compromised, but partial or complete host castration is usually achieved, accompanied by changes in haemolymph proteins (Salt 1927(Salt , 1931Strambi et al. 1982). ...
Recent theory on the role of parasites in the evolution of social behaviour has emphasized the costs of social behaviour to hosts. However, parasites whose primary effect on host fitness is to reduce fecundity can favour the evolutionary origin or maintenance of social behaviour, including eusociality, under certain conditions. If the parasites are not readily transmitted among members of social groups, then other group members will not be selected to reject infected individuals as social partners, nor will adaptive suicide or avoidance of grouping be selectively favoured for infected individuals. Rather, total or partial parasitic castration may promote the expression of helping behaviour by infected individuals. Some parasites may therefore act to increase variance in direct reproductive value within populations or societies, and to promote reproductive division of labour. The necessary conditions of reduced host fecundity and low within-group transmission are met in some insect-parasite systems, and could occur in other host-parasite systems as well.
... It is noteworthy that the results provided by the carbon isotope method agree with those of Strambi and Strambi (1973b), based on labeled amino acids: after 6 h, the silver grains were more abundant in the fat tissue of unextruded X. vesparum females, but not in ''overwintering'' females. Moreover, around 15 days post-eclosion, the level of hemolymph protein in crypto-parasitized wasps was significantly lower than in the healthy ones, suggesting an ''intense metabolic activity'' of the parasite, which at the late 4th instar undergoes a great increase in size (Strambi et al., 1982). The relatively low cost of parasitism for immature wasps is equally explainable in terms of a limited and ''slow growth'' during the host's critical developmental stages (Hughes and Kathirithamby, 2005). ...
... In this sense, the extruded female, after mating and egg fertilization, has finished its main role; it becomes only a protective and suitable container rich of adipocytes and tracheae for thousands of new larvae that will progressively escape from the ventral brood opening. In line with a sustainable exploitation of the host, wasps infected by X. vesparum females spend their inactive but long life out of the colony, without any nutritional depletion (Hughes and Kathirithamby, 2005;Strambi et al., 1982) by the parasite after its extrusion. ...
Females of the endoparasite Xenos vesparum (Strepsiptera, Stylopidae) may survive for months inside the host Polistes dominulus (Hymenoptera, Vespidae). The midgut structure and function in larval instars and neotenic females has been studied by light and electron microscope and by stable carbon isotopic technique. The 1st instar larva utilizes the yolk material contained in the gut lumen, whereas the subsequent larval instars are actively involved in nutrient uptake from the wasp hemolymph and storage in the adipocytes. At the end of the 4th instar, the neotenic female extrudes with its anterior region from the host; the midgut progressively degenerates following an autophagic cell death program. First the midgut epithelial cells accumulate lamellar bodies and then expel their nuclei into the gut lumen; the remnant gut consists of a thin epithelium devoid of nuclei but still provided with intercellular junctions. We fed the parasitized wasps with sugar from different sources (beet or cane), characterized by their distinctive carbon isotope compositions, and measured the bulk (13)C/(12)C ratios of both wasps and parasites. Female parasites developing inside the wasp hemocoel are able to absorb nutrients from the host but, after their extrusion, they stop incorporating nutrients and survive thanks to the adipocytes content.
... In line with our negative results, parasitized P. dominula males, unlike females, are not castrated ; the impact of X. vesparum on their functional morphology is marginal . The effect of the parasite is greater in females, the primary host, than in males (Beani, 2006), as confirmed by parasite-induced changes in haemolymph protein concentration (Strambi et al., 1982), sex-specific cuticular hydrocarbons (Beani et al., 2019) and behaviour (Cappa et al., 2013. Moreover, infected males produce more sperm cells (152 600-560 000 cells; personal observation, ARS) than the amount of sperm stored in the spermatheca (10 000 according to Salerno & Turillazzi, 2001), suggesting that the number of sperm is of minor importance for female mate choice. ...
Females of many social Hymenoptera commit their reproductive potential to a single male; they mate once and never re-mate. Sexual selection theory predicts that under this regimen female precopulatory mate choice is crucial. The targets of female choice, male secondary sexual traits, should convey information about the functional fertility of the male. Here, we evaluated semen quality and its correlates in the paper wasp Polistes dominula, a monandric species with a lek-based mating system. The main goal of the study was to test whether sperm viability and the total number of sperm covaried with sexually dimorphic abdominal spots, body size and parasitic infection by Xenos vesparum. Surprisingly, superior male fertility was not predicted by attractive sexual traits, such as little round spots and large body size. We also found no effect of the parasite on male fertility, sexual ornamentation or body size. We found only that sperm viability was positively associated with the number of sperm. Moreover, there was evidence of a counterintuitive relationship between (sexually unattractive) large irregular spots and large body size of dominant successful males. Overall, our results suggest a condition-dependent trade-off between body size and costly sexual signals.
... In line with our negative results, parasitized P. dominula males, unlike females, are not castrated ; the impact of X. vesparum on their functional morphology is marginal . The effect of the parasite is greater in females, the primary host, than in males (Beani, 2006), as confirmed by parasite-induced changes in haemolymph protein concentration (Strambi et al., 1982), sex-specific cuticular hydrocarbons (Beani et al., 2019) and behaviour (Cappa et al., 2013. Moreover, infected males produce more sperm cells (152 600-560 000 cells; personal observation, ARS) than the amount of sperm stored in the spermatheca (10 000 according to Salerno & Turillazzi, 2001), suggesting that the number of sperm is of minor importance for female mate choice. ...
Females of many social Hymenoptera commit their reproductive potential to a single male; they mate once and never re-mate. Sexual selection theory predicts that under this regimen female precopulatory mate choice is crucial. The targets of female choice, male secondary sexual traits, should convey information about the functional fertility of the male. Here, we evaluated semen quality and its correlates in the paper wasp Polistes dominula, a monandric species with a lek-based mating system. The main goal of the study was to test whether sperm viability and the total number of sperm covaried with sexually dimorphic abdominal spots, body size and parasitic infection by Xenos vesparum. Surprisingly, superior male fertility was not predicted by attractive sexual traits, such as little round spots and large body size. We also found no effect of the parasite on male fertility, sexual ornamentation or body size. We found only that sperm viability was positively associated with the number of sperm. Moreover, there was evidence of a counterintuitive relationship between (sexually unattractive) large irregular spots and large body size of dominant successful males. Overall, our results suggest a condition-dependent trade-off between body size and costly sexual signals. ADDITIONAL KEYWORDS: body size-fertility signals-parasite effect-Polistes dominula-sexual ornaments-sperm quality-Xenos vesparum.
... Как известно, на размеры тела, характер меланизации покровов, физиологию и поведение самок полистов оказывают влияние трофические факторы, включающие характер питания особи на личиночных стадиях и зараженность паразитами, в частности веерокрылкой Xenos vesparum Rossi (Strepsiptera, Stylopidae) и клещом Sphexicozela connivens Mahunka (Acari, Astigmata, Winterschmidtiidae) [8,10,24,34,38]. С другой стороны, показано влияние вибрационной активности основательниц и рабочих в гнезде на продолжительность отдельных стадий преимагинального развития полистов [29]. ...
The extensity and intensity of invasion in wasp Polistes dominula (Christ) males by mite
Sphexicozela connivens Mahunka were studied in 2002–2012.
It was revealed that both males’ invasion parameters correlate with summer weather
conditions (temperature and precipitation). It was shown that males with different reproductive
strategies (territorial males and migrants) do not differ in extensity and intensity of mite
invasion. The relation between the spatial distribution of territorial males and their mite invasion
intensity was found. The factors causing the choice P. dominula males their reproductive
strategy are discussed.
... Parasitized females have undeveloped ovaries and desert the colony without performing any social tasks (Hughes et al., 2004;Beani, 2006;Beani et al., 2011). In a pioneering neuroendocrine study (Strambi et al., 1982), parasitized females were found to have smaller JH-secreting organs (corpora allata) and lower JH-levels. In contrast, the volume of the corpora allata in males decreases with age, as expected, regardless of parasite's presence (unpublished data). ...
... Moreover, even P. dominula gynes may vary in their reproductive quality or value as the species is the primary host for the parasite Xenos vesparum (Strepsiptera, Xenidae). Among the morphophysiological changes induced by the parasite, the most dramatic is the castration of female hosts (Strambi et al. 1982;Beani et al. 2011). Infected females aggregate near leks, where the parasite mates (Beani et al. 2005), increasing their chances of encountering sexually active males. ...
Discrimination among potential partners is a critical step in sexual selection to avoid wasting reproductive
resources on an unsuitable mate. In the female-dominated hymenopteran societies males have
often been regarded as ‘flying sperm containers’ spending all their time and energy in trying to acquire a
mate.We investigated the male sexual preference for potential partners using as a model the primitively
eusocial wasp Polistes dominula in which female caste is rather flexible and difficult to determine. By
means of laboratory bioassays, we compared the males’ behaviour towards females of different reproductive
potential. Males were able to recognize female castes, strongly preferring reproductive females to
workers, regardless of female age or health. The results show that in this species caste plays a key role in
orienting male discrimination and preference, presumably through chemical cues, towards reproductive
females both healthy and parasite-castrated. Overall, our study shows that social Hymenoptera males are
not always ‘small mating machines’ eager to mate.
... Among the morphophysiological changes induced by the parasite, the most dramatic is the castration of the female wasp (Strambi & Strambi 1973;Strambi et al. 1982). Stylopization of the host, that is, the protrusion of the parasite's male puparium or female cephalothorax from the host's abdomen (Fig. 1a), is detectable 5e10 days after host emergence (Hughes et al. 2004b). ...
The macroparasite Xenos vesparum affects both the behaviour and the physical traits of its host, the social wasp Polistes dominulus. Female wasps, if parasitized, do not perform any social tasks and desert the colony to gather at specific sites, where the parasite mates; at the end of summer they form prehibernating clusters joined by healthy future queens to overwinter. Parasitized wasps become highly gregarious. In April, healthy wasps leave the aggregations to found new colonies, while parasitized wasps remain in overwintering groups and release parasites to infect wasp larvae only later in the season. We studied the prolonged gregarious behaviour of parasitized wasps and analysed the morphology of parasitized and healthy wasps in aggregations collected over a 7-year period to determine whether the parasite affects host size, wing symmetry, ovarian development and lipid stores. All parasitized wasps were smaller and had undeveloped ovaries and more wing fluctuating asymmetry than unparasitized wasps, irrespective of time of year, parasite load and parasite sex. If infected only by one or two X. vesparum females, the wasps had large fat bodies, which could facilitate their overwintering. In contrast, wasps infected by at least one male parasite had little lipid and died at the end of the summer. Thus, X. vesparum, may play a role in the fate of its host, by exploiting wasps' tendency to form aggregations outside the colony and by altering its caste system, nutrient allocation, diapause timing and life span to achieve its own reproduction and dispersal.
... There is apparently no cost of parasitism for larval wasps in terms of mortality and weight loss (Hughes and Kathirithamby 2005). However, X. vesparum induces permanent sterility in host female wasps (Strambi and Strambi 1973;Strambi et al. 1982) and alters their morphology, behaviour and fate (Beani 2006;Beani et al. 2011): this suggests that parasitization might have remarkable costs for the host at the colony level, though the fitness of infected and uninfected colonies has yet to be characterized. Here, in the framework of the EICA hypothesis, we examine individual and colony-level responses to X. vesparum parasitization and immune challenge with bacteria and fungi. ...
Successful invaders often become established in new ranges by outcompeting native species. The "evolution of increased competitive ability" hypothesis predicts that invasive species are subjected to less predation and parasitization than sympatric native species, and thus can allocate resources from defence and immunity to growth and fecundity, thereby achieving higher fitness. In this study, we examined whether American invasive Polistes dominula paper wasps have reduced immunocompetence. To explore this scenario, we tested their susceptibility towards parasites and pathogens at both the individual (immune defence) and colony levels, i.e. hygienic behaviour (removal of diseased individuals by nestmates). First, we examined the response to the specific coevolved parasite Xenos vesparum (lost after invasion) in terms of individual host susceptibility and hygienic behaviour. Second, we explored the response against general pathogens by quantifying the bacterial clearance in individual wasps after a challenge with Escherichia coli and hygienic behaviour after a challenge with the fungus Beauveria bassiana. Our results show that American invasive P. dominula have a higher response against X. vesparum at the colony level, but at the individual level their susceptibility is not significantly different from conspecifics of the native range. On the other hand, invasive P. dominula display lower response after a challenge with general pathogens at both the individual and colony levels. While supporting the hypothesis of a reduction of immunocompetence towards general pathogens in invasive species, these findings also suggest that the response against coevolved parasites might follow different evolutionary pathways which are not always easily predictable.
... Pardi, 1946; Khalifa, 1953; Turillazzi, 1980), taxonomic notes (e.g. Brues, 1903; Kifune, 1979; Cook and Mathison, 1997), or physiological alterations due to parasitism (Strambi et al., 1982). Our most thorough knowledge has come from a study of late season nests (Octo Insectes Soc. ...
Summary. hough the paper wasp genus, Polistes, is well studied, we know little of the incidence of parasitism in this group. Here we present details of 45 nest dissections for 4 species: P. dominulus (Christ), P. gallicus (L.), P. stabilinus Richards and P. carnifex (F.) to detail levels of parasitism of colony members by the obligate parasitic group of insects, the Strepsiptera. All 4 species showed evidence of parasitism among immature members. For 3 species, more than 50% of inspected nests were parasitized and the levels of parasitism among brood (larvae and pupae) was very high and did not differ significantly between parasitized nests. One species, P. stabilinus, suffered very low levels of parasitism, which may be related to its habitat choice. The number of parasites per host was positively related to the proportion of infected brood (parasite prevalence) and in some cases reached phenomenally high levels, which casts doubt on previ ously assumed mechanisms of infection for nest-making Hymenoptera, i.e. phoresy. We also document cases of egg parasitism and encapsulation in Polistes nests. Our data show that parasitism levels greatly varied among areas. Finally, the recent debate on the competitive advantage of P. dominulus in its introduced range, USA, has credited an absence of strepsipteran parasites of this species in facilitating its spread. For the first time, we document levels of parasitism for this species in its nature P range and this would appear to corroborate previous claims. We place our work in the context of other studies of parasitism of social insects and posit that the genus Polistes may have much to offer to this field.
... Variability of the melanin pattern, body size, and physiology in paper wasp foundresses is influenced by different climatic and trophic factors and infestation with parasites, in particular Xenos vesparum Rossi (Strepsiptera, Stylopidae) (Turillazzi, 1980;Strambi et al., 1982;Sullivan and Strassmann, 1984 Mahunka (1970) described the larvae, protonymphs, heteromorphous deutonymphs, and adults of the mite Sphexicozela connivens Mahunka occurring in the nests and on the larvae of the paper wasp Polistes dominula (Christ). We found this mite on larvae of P. dominula and P. nimpha (Christ) in the Crimea and in the territory of Kherson Province in the Black Sea Biosphere Reserve. ...
The mites Sphexicozela connivens infesting the larvae of the future foundresses of Polistes nimpha have been shown to affect their size and the melanin pattern of some body parts. Foundresses reared in the infested environment
have shorter wings and paler variants of metasomal sternite IV. The role of such morphotypes in the formation of Polistes nimpha population is discussed.
... sessment and to exit the overwintering period with some characteristics typical of dominant wasps. Here, we evaluated whether dominance potential may already be assessed and improved by social interactions in prehibernating clusters. Actually, physiological differences among foundresses seem to be present before the nest foundation has taken place. Strambi et al. (1982) demonstrated that hibernating P. dominulus gynes are characterized by a bimodal distribution of the hemolymph protein level. Such diversification is not determined at a preimaginal stage as it clearly arises only 16–20 days after the emergence. Accordingly, Röseler (1991) found that in the first hours after hibernation, dominance intera ...
At a very early age several mammals establish a first dominance hierarchy, which often persists into adulthood. Social wasps offer an excellent opportunity to study such a phenomenon in insects. Indeed, foundresses of several paper wasps meet in clusters to hibernate from September to March. In spring, wasps found new associative nests where linear hierarchies occur. In the first phase of hibernation, clustering Polistes dominulus wasps show most of the social interactions occurring on the nest 6 months later. At the emergence from diapause, some females already show some behavioral and physiological traits typical of dominant individuals. Here, we investigated the significance of the interactions in the autumnal clusters. We demonstrated that in a given pair, it is more likely that the dominant wasp in autumn becomes the alpha female in spring after the nest foundation phase occurred. Moreover, we showed that dominant females in clusters have both larger body size and ovaries. As ovarian development mainly depends on the social context, our findings seem to indicate that social factors affect the tendency to dominate in aggregations. Furthermore, we suggest that some females may reinforce their physiological status by dominating in clusters, thus increasing the probability to become dominant in spring.
An annotated taxonomic and nomenclatural catalogue of the insect order Strepsiptera is presented. Known distributions and host associations are given as they are currently known. As of this publication, there are 627 valid species, 28 of which are known only from fossils. The misspelling of Viridipromontorius as Viridopromontoriusn. syn. (Roy and Niladri, 2016) is corrected to include Viridipromontorius aequus n. comb.Caenocholax pierci is moved to the genus Myrmecolax and becomes Myrmecolax pierci (Chattopadhyay and Chaudhuri, 1980) n. comb. Stichotrema trinadadensisGuenther, 1949) n. comb. is moved from Stichotrema to Myrmecolax. Halictophagus bohartiAbdulla, 1974 n. stat. was previously a junior synonym of Halictophagus variatus due to its being an invalid renaming of a homonym. The following species are reinstated as valid: Pseudoxenos andradeiLuna de Carvalho, 1953; Pseudoxenos atlanticusLuna de Carvalho, 1969 n. stat.; Pseudoxenos corcyricusSaunders, 1872; Pseudoxenos klugii (Saunders, 1852); Pseudoxenos lusitanicusLuna de Carvalho, 1960; Pseudoxenos schaumiiSaunders, 1872; Pseudoxenos seyrigi Monod, 1926; Stylops aburanaeKifune and Maeta, 1990 n. stat.; Stylops ainoKifune and Maeta, 1990 n. stat.; Stylops alfkeniHofeneder, 1939 n. stat; Stylops bimaculatae Perkins, 1918 n. stat.; Stylops bisalicidis Pierce, 1918 n. stat.; Stylops championi Pierce, 1918 n. stat.; Stylops collinusKifune and Maeta, 1990 n. stat.; Stylops dentataeKifune and Maeta, 1990 n. stat.; Stylops dominiqueiPierce, 1909 n. stat.; Stylops duboisi Bohart, 1937 n. stat.; Stylops duriensisLuna de Carvalho, 1974 n. stat.; Stylops esteponensisLuna de Carvalho, 1974 n. stat.; Stylops flavipedisHofeneder, 1923 n. stat.; Stylops fukuiensis Kifune, 1991 n. stat.; Stylops giganteusLuna de Carvalho, 1974 n. stat.; Stylops hirashimaiKifune and Maeta, 1990 n. stat.; Stylops izumoensisKifune and Maeta, 1990 n. stat.; Stylops krygeri Pierce, 1918 n. stat.; Stylops mandibularisPierce, 1911 n. stat.; Stylops medionitansPierce, 1919 n. stat.; Stylops moestae Pierce, 1918 n. stat.; Stylops muelleri Borchert, 1971 n. stat.; Stylops neonanae Pierce 1918 n. stat.; Stylops nipponicusKifune and Maeta, 1990 n. stat.; Stylops nitidaePasteels 1954 n. stat.; Stylops nitidiusculaePoluszyński 1927 n. stat.; Stylops oblongulusKifune and Hirashima, 1985 n. stat.; Stylops oklahomaePierce, 1909 n. stat.; Stylops orientisKifune and Maeta, 1990 n. stat.; Stylops pacificusBohart, 1936 n. stat.; Stylops perkinsiPasteels 1949 n. stat.; Stylops saliciflorisPierce, 1909 n. stat.; Stylops subcircularisKifune and Maeta, 1990 n. stat.; Stylops swenkiPierce 1909 n. stat.; Stylops truncatoidesKifune and Hirashima, 1985 n. stat. Stylops truncatusKifune and Hirashima, 1985 n. stat.; Xenos myrapetrus (Trois, 1988).
Vespids are divided into two zoological categories. This distinction is underlined by their rather different biological characteristics. Vespinae exhibit a monogynous foundation. In the progeny, the two female castes are well distinguishable. The queen inhibits the ovaries of the workers and is able to provoke caste differentiation by means of pheromones which it secretes. Thus it maintains the yearly regulation of the colony. In contrast, Polistinae, at least in certain species, are borderline examples of social insects. Castes are often morphologically indistinguishable. The polygynous foundation of their nests necessitates social regulation even within the foundress caste. It is not yet known if any pheromones are involved in the regulation of their social activity. Their physiology and especially endocrinology is better known and it suggests in understanding the endocrine regulation of their society.
In this chapter we review the adverse effects that parasites and parasitoids have on insect fecundity. The potential changes in host resource management that arise from a reduction in the amount of nutrients required for egg production are discussed. The role of two possible mediators are evaluated: nutrient competition between parasite and host, and parasite-induced modulation of the endocrine control of reproduction. Attention is focused on the similarity of the mechanisms underlying fecundity reduction in three model systems, Hymenolepis diminuta infections in Tenebrio molitor, Onchocerca
lienalis infections in Simulium ornatum and Plasmodium yoelii nigeriensis infections in anopheline mosquitoes.
An alien creature slithers into the body of its victim and with machiavellian cunning manipulates its behavior. This disturbing vision has been the premise for more than one successful horror film. As with many human fantasies, this one has a basis in biological fact: some parasites do alter their hosts’ behavior (see Moore and Gotelli, 1990; Horton and Moore, 1993; Moore, 1993, 1995). What is less clear is how they do it.
Of all social insects, probably the least well known are social wasps. This is especially true of the mechanisms of caste induction and the regulation of reproductory functions in the wasp colony.
Societies of social insects are paragons of communication. Multiple channels exist between different members and the transmitted information ranges from specifying the location of foraging areas to who controls reproduction. Whole colonies can also communicate with other colonies or even vertebrates. But what if the individuals within a society are not, in a word, themselves? This chapter explores how adaptive manipulation of host behaviour by parasites, i.e., the extended phenotype of parasites obscures social communication, and it asks how it influences other members of the society. Since manipulated kin are at best cheaters and at worst potential infective agents can the society recognise them? Knowing how a highly complicated example of social communication is broken or subverted by parasites can provide considerable insight into the evolution of communication. The chapter discusses conflict and communication in this system in the context of the debate over the nature of the organism.
Parasitic castration of hosts occurs throughout the animal kingdom, as well as being the result of insect infestations of plant tissues. Specific examples of disruption to the reproductive capability of invertebrate hosts by parasites have been the subject of several reviews (Hurd, 1993; Hurd, 1990a, b; Read, 1990). While these earlier monographs dealt with all classes of invertebrates, not just insects, this chapter will be restricted to insect parasitoid-insect host interactions. Our discussion will be limited to interactions between species of Hymenoptera (primarily bees and wasps), Lepidoptera (butterflies and moths), Coleoptera (beetles), and Strepsiptera (twisted-wing parasites) in the Class Hexapoda. Most of our information will be on hymenopteran parasitoids attacking lepidopteran hosts in their larval or egg stages. Generally, the effect of the parasitoid on the gonads of the host is maximized if the host is young when initially attacked. This is due, in part, to the continual and exponential development of host gonads.
Social behavior occurs in some of the smallest animals as well as some the largest, and the transition from solitary life to sociality is an unsolved evolutionary mystery. The Evolution of Social Wasps examines social behavior in a single lineage of insects, wasps of the family Vespidae. It presents empirical knowledge of social wasps from two approaches: one that focuses on phylogeny and life history; and one that focuses on individual ontogeny, colony development, and population dynamics. It also provides an extensive summary of the existing literature while demonstrating how it can be clouded by theory. This approach to the conflicting literature on sociality highlights how often repeated models can become fixed in the thinking of the scientific community. Instead, it presents a mechanistic scenario for the evolution of sociality in wasps that changes our perspective on kin selection, the paradigm that has dominated thinking about social evolution since the 1970s.
The effects of metacestodes of Hymenolepis diminuta on haemolymph proteins of Tenebrio molitor are restricted to female hosts. In beetles aged 15 days post-emergence, and harbouring 12-day-old metacestodes, haemolymph concentration is 46·7% higher than in non-infected animals and similar effects are found in longer standing infections. Electrophoresis of haemolymph revealed the presence of 13 bands. Densitometric analysis showed that only band 2/3 was significantly elevated in infected hosts although band 7/8 also showed an increase. These bands were also present in egg homogenates and are thought to be vitellogenins. It is therefore proposed that the excess protein found in infected beetles is a female-specific protein resulting from an interaction between the parasite and the host endocrine system.
Seasonal changes in the coloration of the clypeus, mesonotum, and abdomen were studied in populations of the paper wasp, Polistes dominulus (Christ) in southern Ukraine. The color patterns in the populations were found to be different before and after hibernation.
The frequencies of color morphs observed in the autumns of different years are similar, while the frequencies observed in
spring vary from year to year. A tendency for pleometrosis is manifested by females of different color morphs in different
years. The nest usurpers have darker patterns of the clypeus. A polyfunctional role of the coloration and pattern is supposed.
Host fertility is often curtailed as a result of parasitic infection. The hypothesis that this may confer an adaptive advantage upon the symbionts if nutrients are directed from reproduction and made available for host/parasite maintenance is explored. The suggestion is made that an understanding of the mechanisms underlying the pathophysiology of fecundity reduction may shed light upon the evolutionary implications of this strategy for both parasite and host. To illustrate this the down-regulation of egg production is explored with reference to a particular model system, the association between metacestodes of the rat tapeworm, Hymenolepis diminuta and the mealworm beetle, Tenebrio molitor. Several aspects of host reproductive behavior and physiology are affected by infection in this association, including vitellogenesis. Metacestodes directly inhibit the fat body synthesis of vitellogenin in a stage-specific, density-dependent manner. This inhibition is likely to be orchestrated by a modulator molecule, produced by the parasite. In the ovarian follicles, juvenile hormone III binding to a specific follicular membrane-binding protein is inhibited in infected beetles, resulting in the down-regulation of a cascade of events which enables vitellogenin to pass into the developing oocyte. Data to support the proposed existence of a parasite-induced antigonadotrophin, of host origin, are discussed. Evidence that similar mechanisms operate in Plasmodium-infected anopheline mosquitoes and Onchocerca-infected blackflies is presented in support of the possibility that a parasite-induced reduction in host reproductive fitness is an adaptive strategy and an assessment of who is manipulating whom is made.
Polistes dominulus are social wasps which are the host of the strepsipteran endoparasite Xenos vesparum. In the hibernating phase, unparasitized and parasitized wasps leave natal nests and aggregate together in sheltered quarters. In aggregations, wasps are socially active, and some individuals perform helping behaviour. Here we investigated if castrated parasitized wasps perform worker tasks in mixed aggregations. Moreover, by gas chromatography and mass spectrometry, we examined the cuticular hydrocarbons of unparasitized and parasitized wasps to evaluate if the infection alters the composition of cuticular waxes that are recognition cues in social insects. In clusters, infected females do not perform helping behaviour and they are less active than unparasitized wasps. Cuticular hydrocarbons are slightly differentiated between unparasitized and parasitized wasps but, generally, unparasitized wasps are more similar to wasps infected by Xenos females compared to wasps infected by Xenos males. Wasps infected by Xenos males do not usually survive the winter. This chemical similarity is probably a consequence of the similar physiological condition of unparasitized and female-affected Polistes wasps. At this stage, it is difficult to affirm whether these modifications are a true parasite manipulation or a consequence of infection.
The changing patterns of haemolymph proteins were followed in male and female adults of normal and parasitized Anacridium aegyptium during diapause (autumn, winter) or during activity (spring) of their endocrine system without or with electrostimulations of the pars intercerebralis (PI).The haemolymph protein concentration is high in winter and decreases in spring. It is comparatively depleted in locusts infected by the fly Metacemyia calloti. However, the depletion is significant only in ‘castrated’ females.Fifteen protein fractions were resolved by polyacrylamide disk gel electrophoresis in haemolymph of normal and infected locusts during diapause and activity. Some fractions decrease in quantity during activity in males, normal females, and parasitized females with complete ovarian development. One fraction disappears in females with mature eggs and seems correlated with formation of the eggshell. Eight others protein fractions exhibit electrophoretic mobility identical to the 7 protein fractions of homogenates of eggs. There is little doubt that these haemolymph protein fractions are involved in yolk synthesis and are thus ‘vitellogenic’. One of these ‘vitellogenic’ fractions (band 6) is larger in yolk than in blood.Five protein fractions were demonstrated by electrophoresis of homogenates of parasites. Their electrophoretic mobilities are similar to those of 5 of the 8 haemolymph ‘vitellogenic’ fractions of the host. There is little doubt that these 5 haemolymph protein fractions (one of them is the band 6) are involved in the nutritional requirements of the parasite.Electrostimulation of the PI, during diapause and activity, increase the haemolymph protein concentration and chiefly the protein concentration of the blood band 6. Thus, the median neurosecretory cells of the brain (M-NSC) regulate protein synthesis and chiefly the synthesis of ‘vitellogenic’ proteins.In parasitized females, the increase of the haemolymph protein concentration after electrostimulations of the PI is associated with an enhancement of ovarian development. The depletion of the haemolymph protein concentration in ‘castrated’ females is thus involved in the inability of the oöcytes to sequester available proteins from the haemolymph. The haemolymph protein deficiency may be attributed to (1) an impairment of protein synthesis, attendant upon the hypoactivity of the M-NSC, and (2) the nutritional requirements of the parasite.
The effects of the parasitoid on the development, behavior, physiology, and morphology of the host have been described and often attributed to the feeding larvae within the host. It has become increasingly clear that these effects on the host are often due to factors injected into the host by the ovipositing female. This realization, along with the realization that the host is often dramatically altered after oviposition by the parasitoid, has given rise to the concept of host regulation as one of the key aspects of parasitoidism. The physiological and biochemical changes that occur after parasitoidism are described. These include paralysis; changes in growth, feeding, and development; changes in hemolymph solutes, proteins, carbohydrates, lipids, nitrogen metabolism and excretion; as well as changes in select tissues including the endocrine and reproductive system of the host. The sources of the factors that may elicit these changes are discussed and include the role of the adult female, her progeny, and...
The median neurosecretory cells (M-NSC) of Anacridium aegyptium were studied by light and electron microscopy during the ovarian diapause (autumn and winter) and the ovarian activity (spring) in normal females and in females infected by a tachinid fly Metacemyia calloti. In spring, the M-NSC contain comparatively much stainable material in normal females than in parasitized ones. This difference results from the ovarian maturity of normal females and the ovarian immaturity of parasitized females.The activity of the M-NSC was assessed in spring using the evolution of the radioactivity of the pars intercerebralis (PI) and corpora cardiaca (CC) after injection of 35S-cysteine. The activity of the M-NSC is impaired in the parasitized females without ovarian development.The ovarian diapause was broken by massive implantations of corpora allata (CA) or electrical stimulations of the PI. Implantations of CA induce in parasitized females the same state of ovarian development than during natural activity in spring. Electrical stimulations of the PI. which increase the activity of the M-NSC. enhance the ovarian development of the parasitized females. A hypoactivity of the M-NSC is involved in the ‘castration’ of the Egyptian grasshopper.
The injection of high doses of JH-III into adult worker honeybees causes the hypopharyngeal glands to degenerate and lowers the vitellogenin synthesis rate as well as the total haemolymph protein concentration. The injection of low doses increases the protein titre and stimulates vitellogenin synthesis while the hypopharyngeal glands develop.The effects of high doses of JH corresponds to the normal physiological changes in the ageing bee, especially at the time of the transformation into field bees. Hormone titre measurements show a drastic increase during adult life, which together with the injection experiments seems to indicate stimulating effects of low JH titre on protein synthesis and hypopharyngeal gland development during the first phase of adult life, and inhibiting and degeneration inducing effects of the high JH titre during the second phase of life.Thus it is possible that the physiological changes correlated with changes in behaviour of the adult worker bee are controlled by the JH titre.
The soluble proteins of haemolymph during the life cycle from adult bumblebee queens (Bombus terrestris) were separated by disk electrophoresis on polyacrylamide gels. Twenty-three fractions stainable with amido black were detected. Every phase of the bee's adult life is characterized by a specific pattern of haemolymph proteins.Newly emerged queens have a low haemolymph protein concentration which increases in the first 5 days to a maximum. The high concentration is probably connected with the synthesis of hibernation reserves. Before the beginning of hibernation the concentration of some protein fractions seems to decrease; the concentration of these fractions is low also after hibernation.During the spring the first oöcytes begin to grow and the activity of corpora allata, hypopharyngeal glands, and wax glands reaches a maximum at the time of starting nests. A large increase in the concentration of haemolymph proteins is correlated with the activity of these glands. This high concentration does not change during the whole egg-laying period; however, the concentration decreases to a minimum in old queens with degenerating ovaries.In the protein pattern of ovary homogenate we detected three fractions with an RF identical to haemolymph fractions. Investigations on queens parasitized with the nematode Sphaerularia bombi confirmed that these fractions are yolk material (vitellogenin) taken up by ovaries. In parasitized queens oöcytes do not grow and the fractions are of a much lower concentration than in nonparasitized queens with maturing eggs. Therefore it appears that the parasite injures primarily the corpora allata known to stimulate the synthesis of yolk protein.
The haemolymph protein concentration of active females with developing ovaries is relatively low. It increases at the beginning and decreases towards the end of each reproduction cycle. In allatectomized or castrated females the haemolymph proteins accumulate excessively, the concentration being 3·5 to 4 times higher than that of active females. Implantation of a corpus allatum into allatectomized females induces ovarian development and causes a decrease of the haemolymph protein concentration to the level found in active females. Cardiac-allatectomized or diapausing females showed also an increased haemolymph protein concentration, although it never reached the high values observed in allatectomized females. The haemolymph protein concentration of males was constantly low.It is suggested that the effect of hormones on the haemolymph protein concentration is indirect. The activation hormone stimulates the processes of digestion and thus enables synthesis of the reserve materials which accumulate in the haemolymph or in some other tissues. The corpus allatum hormone stimulates the egg maturation process and thus facilitates consumption of the reserve material.
1.
Autumnal nest populations ofPolistes exclamans include externally indistinguishable workers and future queens. Qualitative as well as quantitative caste differences were found in the parietal fat body.
2.
An interesting correlation exists between the type of fat body and amount of eye pigmentation in females of this species.
3.
The frequency of transfer of marked males between nests was found to be very low.
4.
Polistes exclamans is unusual among North American members of its genus in that it appears to be almost completely haplometrotic in parts of its range. This may be evolutionarily connected with the species' comparatively greater vagility and tendency to disperse. Nest dispersal may reduce the rate of parasitism.
1.
Im Oberschlundganglion der Sandbiene Andrena vaga Pz. lassen sich neurosekretorische Zellen in der Pars intercerebralis nachweisen. Eine zweite Gruppe neurosekretorischer Zellen schliet sich posterior an die vordere an. Die ableitenden Axone beider Gruppen werden beschrieben sowie der Verlauf der Nervi corporis eardiaci und der Nervi corporis allati.
2.
Das Unterschlundganglion enthlt zwei kappenartig aufsitzende Regionen neurosekretorischer Zellen.
3.
Ein Ganglion hypocerebrale fehlt, der Nervus recurrens ist urpaar und steht mit den Corpora cardiaca und Corpora allata nicht in Verbindung.
4.
Die Corpora cardiaca sind aus verschiedenen Zellelementen kompliziert aufgebaute Organe, denen wahrscheinlich auer der Speicherung und Verteilung des Neurosekrets sowie der Produktion eines eigenen Sekrets noch andere Funktionen zugesprochen werden mssen.
5.
Stichproben an den Corpora allata mnnlicher Sandbienen ergaben ein Verhltnis des Volumens der Corpora allata von gesunden zu stylopisierten Tieren wie 2 zu 1. Die unterentwickelten Corpora allata fanden sich sowohl bei Andrena-/Strylops- als auch bei Andrena-/Strylops-.
6.
Eine Volumenzunahme der Corpora allata auf das 2–3fache und erhhte Aktivitt der allata-Zellen sind bei gesunden Sandbienen- im Zusammenhang mit Dotterproduktion und Eireifung zu beobachten.
7.
Im Falle der Andrena-/Stylops- ist die Hemmung der Corpora allata sehr gering und dauert auch nur so lange, wie sich der Parasit im Wirt befindet. Im Falle Andrena/Stylops- jedoch werden das Wachstum wie auch die normale Funktion der allata-Zellen ganz unterdrckt.
8.
Die Beziehungen zwischen Corpora allata und Ovar werden besprochen. Bei Andrena-/Stylops- beruht die Hemmung von Corpora allata und Ovar des Wirtes sehr wahrscheinlich auf einem Eiweimangel. Das Eiwei wird dem Wirt wahrscheinlich whrend seiner Verpuppung von den noch nicht verpuppten zuknftigen Stylops-Weibchen entzogen.
9.
Der Fettkrper wird bei gesunden und stylopisierten Sandbienen- bis auf einen Rest langsam abgebaut.
10.
Versuche, die Wirkung des weiblichen Parasiten durch Herausnehmen aus ihren Wirten aufzuheben, andererseits durch Injektionen von Parasitenextrakten in Versuchstiere (Triatome infestans
Neiva) ihre Wirksamkeit zu prfen, muten aus Materialmangel abgebrochen werden.
In females ofPolistes gallicus the activity of corpora allata (CA) was determined volumetrically as well as radiochemically using the in vitro assay for juvenile hormone (JH). The results we have compared with the ovarian activity. During the period of egg maturation after overwintering the volume of CA is well correlated with the synthetic activity. But in overwintering females and in ovariectomized females we have observed very large glands which produced only little amounts of JH like the small glands of parasitized wasps. In all dominant females the CA we have found to be larger and more active than in subordinated females indicating that changes in the endocrine activity may be a primary result of social hierarchy.Chez des femelles dePolistes gallicus, nous avons examin le volume des corpora allata et leur activit de synthse in vitro estime grce au dosage radiochimique de l'hormone juvnile. Les valeurs obtenues sont compares avec l'activit ovarienne.Pendant la premire priode de maturation des ovocytes, la sortie de l'hivernage, le volume des corpora allata est en nette corrlation avec leur activit de synthse. Cependant, chez des femelles hivernantes ou ovariectomises, nous avons observ de trs grosses glandes ne produisant que de petites quantits d'hormone juvnile. Les petits corps allates des femelles stylopises ont une activit de synthse trs faible.Chez toutes les femelles dominantes, les corpora allata sont plus grands et plus actifs que chez les subordonnes; les changements d'activit endocrinienne semblent lis l'tablissement d'une hirarchie sociale entre les fondatrices.
1.1. Using polyacrylamide disc electrophoresis, eight soluble protein fractions were demonstrable in measurable amounts within the yolk of Schistocerca gregaria.2.2. Female locusts were infected 3 days after their imaginal moult with equal doses of Mermis nigrescens ova and electropherograms of their haemolymph and fat body proteins were compared with a group of uninfected (control) females. Effects of the parasite upon host protein turnover were appraised in relation to the host's gonotropic cycle.3.3. The nematode caused only a sporadic depletion of vitellogenic and non-vitellogenic protein fractions before and during the vitellogenesis period of controls (initial 2 weeks' infection). The ability of the terminal oocytes to sequester vitellogenic proteins from the host haemolymph was impaired by the parasite, so vitellogenesis commenced but was not completed in infected hosts.4.4. At 3 weeks' infection, haemolymph protein fractions were significantly diminished (cf. controls) by parassitism but were not so depleted 3 days later. Concurrently, terminal and penultimate oocytes of infected locusts were resorbed.5.5. Effects of the nematode on the insect's fat body soluble proteins preceded analogous changes in haemolymph protein fractions. Two weeks after infection, ten of seventeen soluble protein fractions were significantly depleted in the fat bodies of infected locusts (cf. controls). Three weeks after infection, only six fat body protein bands were significantly depleted in infected insects (cf. controls) whilst four such protein fractions were present at significantly higher levels than in the controls.6.6. The nematode stimulates catabolism and/or suppresses anabolism of proteins by the host fat body, to provide a dietary source of amino acids within the haemolymph. This effect of M. nigrescens parasitism upon protein turnover in the locust is discussed in relation to host vitellogenesis, growth requirements of the developing parasite and possible involvement of the host endocrine system.