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Egg extrusion patterns were investigated as an inducible defensive mechanism in potato plants against the leafminer Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae). Increased multiplication rates in leaf cells surrounding an egg of L. huidobrensis leads to its exposure through the leaf cuticle, which might increase the risk of mortality....
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... to 80% of 122 leafminer eggs were extruded in young potato plants (Figure 1), with no significant differences being found between basal and apical leaves ( G 1⁄4 0.91, P 1⁄4 0.33). Egg extrusion rates varied depending on leaf age in mature potato plants ( G 1⁄4 66.83, P 5 0.0001): 17% of 291 eggs were extruded in apical, still expanding leaves, whereas there was no evidence of extrusion for the 260 eggs inserted in basal, fully expanded leaves (Figure 1). No significant differences were found in egg density between basal and apical leaves, neither in mature plants (2.06 + 0.26 and 2.05 + 0.46 eggs/cm 2 respectively; U 1⁄4 191.00, P 1⁄4 0.35) nor in young plants (basal 0.43 + 0.07, apical 0.49 + 0.1 eggs/cm 2 ; t 1⁄4 7 0.46, P 1⁄4 0.65). The number of eggs per unit of leaf area was higher in mature than in young plants, which might have affected plant response. However, extrusion in mature plants was still remarkably lower ( G 1⁄4 45.99, P 5 0.0001) when only leaves of both plant types with equivalent values of egg density were compared 2 (range: 0.1 – 0.97 eggs/cm ). Moreover, there was no correlation between egg density and extrusion rate, neither in mature ( r 1⁄4 0.17, P 1⁄4 0.44, apical leaves only) nor in young plants ( r 1⁄4 7 0.17, P 1⁄4 0.56). Field data showed a significant decrease ( F 1⁄4 10.69, df 1⁄4 2, P 1⁄4 0.010) in the percentage of mined leaves, from lower to upper foliage (Figure ...
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... Egg extrusion is referred to as a hypersensitive reaction that causes hypertrophic cell growth, which eventually leads to egg ejection (Facknath 2005). Egg extrusion is very high in the young leaves and relatively low in the older leaves, because of the hypertrophic cell growth of the new leaves, which leads to egg ejection, and which exposes the eggs to the environment and to the pest's natural enemies (Facknath 2005;Videla and Valladares 2007). ...
The leaf miner, Liriomyza huidobrensis (Diptera: Agromyzidae) is a polyphagous fly, which infests a wide range of vegetables and ornamental plants. However, scant knowledge exists of the biology and ecology of the pest in the Western Cape province of South Africa, both of which are essential components in developing an effective management programme. Several aspects of its biology and ecology were studied in two potato [Solanum tuberosum L. (Solanales: Solanaceae)] fields in the Sandveld region during both winter and summer months. The population densities of adult L. huidobrensis were monitored using yellow sticky traps, which were retrieved and counted once every two weeks (June 2019 to January 2020). The number of leaf miner adults caught throughout the summer and winter monitoring periods was significantly different. In addition, 50 randomly selected plants were assessed for leaf damage (in the form of punctures and mines) using presence/absence sampling. Leaf miner persistence within the soil was confirmed through one-time soil sampling of the two fields, one month after harvesting. Leaf miner pupae were detected in the soil samples after the potatoes were harvested. However, no adult emergence was recorded among the collected pupae under laboratory conditions. The observed trend was that the traps, in both fields, caught an increasing number of leaf miners as the crops matured. Damage occurred in both the monitored fields as early as week four, after plant emergence. Of the five parasitoid species collected, Diglyphus isaea (Hymenoptera: Eulophidae) was the most abundant.
... In South Africa, leaf miner outbreaks are usually severe during summer when temperatures are high (Adendorff 2010;Visser 2009;Weintraub et al. 2017). Additionally, in a study by Videla & Valladares (2007), it was shown that the potato plant expresses a degree of mechanical resistance against the larvae and eggs of L. huidobrensis. In young actively growing leaves, eggs and young larvae are physically "pushed out" by an increase in the multiplication rates of leaf cells, thereby exposing the immatures to predation and increasing the risk of desiccation (Videla & Valladares 2007). ...
... Additionally, in a study by Videla & Valladares (2007), it was shown that the potato plant expresses a degree of mechanical resistance against the larvae and eggs of L. huidobrensis. In young actively growing leaves, eggs and young larvae are physically "pushed out" by an increase in the multiplication rates of leaf cells, thereby exposing the immatures to predation and increasing the risk of desiccation (Videla & Valladares 2007). ...
Although agriculture is crucial to economic growth in South Africa, the industry faces several challenges, including the effects of pests and diseases that contribute to crop loss. Such losses severely affect the maintenance of food security. Therefore, a major challenge is finding effective, environmental-friendly control measures for insect pests. Potatoes are among the four most widely consumed vegetable crops worldwide. However, a potato crop can be infested by various pests, like the devastating leaf miner, Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae). The leaf miner species has, since the early 2000s, become an important pest of various vegetable crops in South Africa. The species is highly invasive, causing up to 70 % damage of solanaceous crops. The damage that is caused by the leaf miner is direct, resulting from the female flies feeding on the leaf mesophyll during oviposition, and the larvae mining the leaves. Indirect damage is induced through pathogens entering through perforations that act as vectors of plant diseases. Biocontrol agents, e.g. entomopathogenic nematodes (EPNs), entomopathogenic fungi (EPF), and parasitoids have shown potential against L. huidobrensis. This review investigates the biology and morphological identification of L. huidobrensis, its host range in the Western Cape, and the potential of associated biocontrol agents, like EPNs, EPF and parasitoids, as future control options.
... The use of resistant germplasm has been reported as the most suitable practice for the control of the leaf miner (Weigand 1990;Singh and Weigand 2006). Thus, the improvement of chickpea cultivars for resistance to the leaf miner is a major concern in integrated pest management (IPM) programs (Videla and Valladares 2007;Toker et al. 2010Toker et al. , 2012Ikten et al. 2015). In previous studies, 200 annual wild Cicer species were screened for resistance to the leaf miner at the International Center for Agriculture Research in the Dry Areas (ICARDA) and two accessions of C. cuneatum Hochstetter ex A.Rich. 10 accessions of C. judaicum Boissier were found to be highly resistant (Singh and Weigand 1994), but C. cuneatum and C. judaicum do not have compatibility with the cultivated chickpea in interspesific crosses (Mallikarjuna and Muehlbauer 2011). ...
The chickpea leaf miner, Liriomyza cicerina (Rondani) (Diptera: Agromyzidae), is an important pest of cultivated chickpea (Cicer arietinum L.). A 2-year field study was carried out to screen a total of 126 Cicer germplasm for resistance to the leaf miner during the 2012 and 2013 growing seasons. Resistance was evaluated using a visual scale of 1–9, where 1 = highly resistant and 9 = very highly susceptible under natural infestation conditions. The results showed that two C. arietinum accessions, ILC 3397 and Sierra, had a score of 9 on the scale, being very highly susceptible. Three germplasm, one mutant (3304) and two breeding lines (LMR 140 and LMR 160) of C. arietinum, were found to be highly resistant with the scores ranging from 1.5 to 2 for resistance to the leaf miner. The mutant, 3304, was detected for the first time in this study as a highly leaf miner-resistant mutant of the cultivated chickpeas while the other two breeding lines had been previously reported as highly resistant against the leaf miner. In addition, two mutants and 14 breeding lines of C. arietinum and two mutants and one germplasm of C. reticulatum were identified as resistant having the scores from 2.1 to 3 on the 1–9 scale. The results suggest that these resistant germplasm may add a new dimension to chickpea breeding programs because they possess valuable traits for resistance against the pest. The resistant chickpeas that can be grown without using pesticides are important as environmental protection and reliable food source for human health.
... Induced secondary metabolites, anti-nutritive compounds and toxins in plants produced in response to insect infestation and/ or elicitor application result in decreased oviposition and reduced larval growth and development (Seino et al. 1996;Petzold-Maxwell et al. 2011;War et al. 2013a). The neoplasm formation (excessive growth of hard tissue) (Doss et al. 2000;Petzold-Maxwell et al. 2011), hypersensitive response/necrosis (Balbyshev and Lorenzen 1997;Doss et al. 2000;Petzold-Maxwell et al. 2011;War et al. 2017), production of ovicides (Seino et al. 1996), release of volatiles to attract egg or larval parasitoids (Hilker et al. 2002;Hilker and Meiners 2006), egg crushing (Desurmont and Weston 2011) and egg extrusion (Videla and Valladares 2007) are some of the important plant defensive responses to insect oviposition. ...
There is always a silent war between plants and herbivorous insects that we are rarely privy to. In this
silent war, chemicals act as both weapons and messengers. Insect–plant co-evolution is going on for millions of
years. Plants always look for new strategies to avoid insect pests and insects, in turn, are always ready to develop
counter-adaptations. This intricate interaction has led to the development of a number of plant defensive traits and
the counter-adaptive features in insects as well. Both plants and insects have developed morphological and bio-
chemical defensive traits to dodge each other’s strategies. However, biochemical interactions are considered more
important and effective than morphological ones because of their dynamic nature. Some of the plant defensive
traits evolved during this evolution include toxic furanocoumarins, toxic amino acids, trichomes, lignin and latex.
Since there is an increasing focus on improving crop production through safe and sustainable means by reducing
the reliance on pesticides, it is highly important to understand the plant defensive traits against insect herbivory. It
is equally important to understand the adaptations by insect pests to these defensive traits in order to develop and
deploy management strategies to outsmart the insect pests. Here we discuss the plant defence traits against insect
herbivory, their induction by elicitors and/or insect damage, and the counter-adaptation by insect pests.
... Healthy, vigorously growing potato plants are able to counteract the damaging effect of leafminers, particularly during the vegetative phase, as long as they come from high quality, pathogen-free seed potatoes and are not deficient in irrigation or fertilizer. One very unusual aspect of young potato plants is that they have an induced resistance mechanism of extruding leafminer eggs (Gonzales 1994, Videla and Valladares 2007. In this mechanism, cells surrounding the eggs multiply at a higher rate than normal and literally cause the egg to be pushed out of the leaf, above the cuticle layer, thus increasing risk of mortality from predation and desiccation. ...
... In this mechanism, cells surrounding the eggs multiply at a higher rate than normal and literally cause the egg to be pushed out of the leaf, above the cuticle layer, thus increasing risk of mortality from predation and desiccation. Researchers found that all leaves of young potato plants (leaves still expanding) extruded eggs at rates ranging from 70 to 90% and 60 to 100% of these eggs died Cisneros 1997, Videla andValladares 2007). In South Africa, Muller and Krü ger (2008) demonstrated that leafminers appear to attack a field randomly, not moving from the border rows inward. ...
... In Argentina, an IPM approach has been advocated (although not yet implemented) for L. huidobrensis on potato and tomato crops in Buenos Aires province (Vincini and Carmona 2006), with studies considering population dynamics of the pest and its main parasitoids, calculation of economic damage thresholds, efficiency of yellow sticky traps, and the use of cultivar resistance, based on plant traits such as foliage coloration (L opez et al. 2010) or egg extrusion capability (Videla and Valladares 2007). ...
Liriomyza huidobrensis (Blanchard) is native to South America but has expanded its range and invaded many
regions of the world, primarily on flowers and to a lesser extent on horticultural product shipments. As a result
of initial invasion into an area, damage caused is usually significant but not necessarily sustained. Currently, it
is an economic pest in selected native and invaded regions of the world. Adults cause damage by puncturing
abaxial and adaxial leaf surfaces for feeding and egg laying sites. Larvae mine the leaf parenchyma tissues
which can lead to leaves drying and wilting. We have recorded 365 host plant species from 49 families and
more than 106 parasitoid species. In a subset of the Argentinian data, we found that parasitoid community composition
attacking L. huidobrensis differs significantly in cultivated and uncultivated plants. No such effect was
found at the world level, probably due to differences in collection methods in the different references. We
review the existing knowledge as a means of setting the context for new and unpublished data. The main
objective is to provide an update of widely dispersed and until now unpublished data, evaluate dispersion of
the leafminer and management strategies in different regions of the world, and highlight the need to consider
the possible effects of climate change on further regional invasions or expansions.
... Induced defenses that displace or kill eggs before hatching should be advantageous because plants will not then sustain herbivore damage. A variety of egg-induced defenses that dislodge or remove the eggs from host plants have been reported (Hilker & Meiners, 2006); some plants directly kill eggs by producing ovicidal substances (Seino et al., 1996 ) or by changing the physical structure or physiological conditions at the oviposition site (Shapiro & DeVay, 1987; Balbyshev & Lorenzen, 1997; Doss et al., 2000; Videla & Valladares, 2007; Desurmont & Weston, 2011; Petzold-Maxwell et al., 2011), and some plants release airborne signals to announce the existence of insect eggs to egg parasitoids and egg parasitoids (Hilker et al., 2002; Colazza et al., 2004). On the other hand, eggs deposited on plant tissue do not always hatch and result in herbivory. ...
Defense priming is defined as increased readiness of defense induction. A growing body of literature indicates that plants (or intact parts of a plant) are primed in anticipation of impending environmental stresses, both biotic and abiotic, and upon the following stimulus, induce defenses more quickly and strongly. For instance, some plants previously exposed to herbivore-inducible plant volatiles (HIPVs) from neighboring plants under herbivore attack show faster or stronger defense activation and enhanced insect resistance when challenged with secondary insect feeding. Research on priming of antiherbivore defense has been limited to the HIPV-mediated mechanism until recently, but significant advances were made in the past three years, including non-HIPV-mediated defense priming, epigenetic modifications as the molecular mechanism of priming, and others. It is timely to consider the advances in research on defense priming in the plant-insect interactions.
... Third, oviposition , one of the most common events preceding insect larval herbivory, can induce a variety of direct and indirect defenses of plants [19,20] . Mechanisms of oviposition-induced defenses include production of ovicides [21], a hypersensitive response or necrosis leading to drying or dropping of eggs222324, excessive growth of hard tissue (neoplasm) under the eggs to force neonates to hatch outside and be exposed to harsh environment [24,25], egg crushing [26], egg extrusion [27], and calling in egg or larval parasitoids by the host plant282930. While most of previous studies of oviposition-induced plant defense have focused on defenses that remove or kill insect eggs from the host [19,20], there have been only two reports of the effect of insect oviposition on the quality of the host plant as food source and thus on the performance of emerging neonates. ...
Insect oviposition on plants frequently precedes herbivory. Accumulating evidence indicates that plants recognize insect oviposition and elicit direct or indirect defenses to reduce the pressure of future herbivory. Most of the oviposition-triggered plant defenses described thus far remove eggs or keep them away from the host plant or their desirable feeding sites. Here, we report induction of antiherbivore defense by insect oviposition which targets newly hatched larvae, not the eggs, in the system of tomato Solanum lycopersicum L., and tomato fruitworm moth Helicoverpa zea Boddie. When tomato plants were oviposited by H. zea moths, pin2, a highly inducible gene encoding protease inhibitor2, which is a representative defense protein against herbivorous arthropods, was expressed at significantly higher level at the oviposition site than surrounding tissues, and expression decreased with distance away from the site of oviposition. Moreover, more eggs resulted in higher pin2 expression in leaves, and both fertilized and unfertilized eggs induced pin2 expression. Notably, when quantified daily following deposition of eggs, pin2 expression at the oviposition site was highest just before the emergence of larvae. Furthermore, H. zea oviposition primed the wound-induced increase of pin2 transcription and a burst of jasmonic acid (JA); tomato plants previously exposed to H. zea oviposition showed significantly stronger induction of pin2 and higher production of JA upon subsequent simulated herbivory than without oviposition. Our results suggest that tomato plants recognize H. zea oviposition as a signal of impending future herbivory and induce defenses to prepare for this herbivory by newly hatched neonate larvae.
... The number of newly initiated mines per leaf area unit (cm 2 ), commonly assumed to reXect egg distribution (Parrella et al. 1983;Marino and Cornell 1993;Mayhew 1998), was used as an indicator of oviposition preference. Although egg mortality might obscure the relationship between larval and egg distribution on some hosts (Videla and Valladares 2007) egg survival did not diVer among the host plants here considered, as shown in the laboratory tests (see Fig. 3 in "Results", below). ...
Insect preferences for particular plant species might be subjected to trade-offs among several selective forces. Here, we evaluated, through laboratory and field experiments, the feeding and ovipositing preferences of the polyphagous leafminer Liriomyza huidobrensis (Diptera: Agromyzidae) in relation to adult and offspring performance and enemy-free space. Female leafminers preferred laying their eggs on Vicia faba (Fabaceae) over Beta vulgaris var. cicla (Chenopodiaceae), in both laboratory and field choice experiments, although no oviposition preference was observed in no-choice tests. Females fed more often on B. v. var. cicla (no-choice test) or showed no feeding preference (choice test), even when their realized fecundity was remarkably higher on V. faba. Offspring developed faster, tended to survive better, and attained bigger adult size on the preferred host plant. Also, a field experiment showed higher overall parasitism rates for leafminers developing on B. v. var. cicla, with a nonsignificant similar tendency in field surveys. According to these results, host plant selection by L. huidobrensis appears to be driven mainly by variation in host quality. Moreover, the consistent oviposition choices for the best host and the labile feeding preferences observed here, suggest that host plant selection might be driven by maximization of offspring fitness even without a conflict of interest between parents and offspring. Overall, these results highlight the complexity of decisions performed by phytophagous insects regarding their host plants, and the importance of simultaneous evaluation of the various driving forces involved, in order to unravel the adaptive significance of female choices.
The stone leek leafminer, Liriomyza chinensis (Kato) (Diptera: Agromyzidae) , is recognized as one of the most destructive pests of the bunching onion. Varietal resistance against L. chinensis has been reported in Allium fistulosum in Japan. We report a new method for evaluating the antibiosis of bunching onions with varietal resistance to L. chinensis by artificially inoculating leaves with L. chinensis eggs. New no-choice tests were performed via the collection and artificial inoculation of L. chinensis eggs into unifacial leaves with a plunger microsyringe and the quantification of the number of individuals that reached the pupal stage in the soil after 14 days of inoculation at 24 °C; these tests were established and conducted to determine the resistance categories of several varieties of A. fistulosum. Antibiosis studies revealed a significant difference in survival to the pupal stage, forewing lengths of adults and development time from the egg to pupal stages among the resistant and susceptible varieties of A. fistulosum, indicating that antibiosis is an important factor in the varietal resistance of A. fistulosum. Furthermore, the antibiosis of the highly resistant varieties ‘Beicong’ and ‘Kokusen natsuyo’ revealed egg killing defenses against L. chinensis.
Host preferences of phytophagous insects, although generally showing a strong hereditary component, can be modified by experience. Here we aim to elucidate the relative roles of larval and adult experience on host plant selection by Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae), a widely distributed pest on ornamentals and vegetables. Laboratory and field experiments evaluating feeding and oviposition preferences of L. huidobrensis females with larval, adult, or larva plus adult experience on either Vicia faba L. (Fabaceae) or Beta vulgaris var. cicla L. (Chenopodiaceae) were performed. Also, we measured offspring performance of L. huidobrensis on both host plant species. Our results show that L. huidobrensis females strongly preferred V. faba over B. vulgaris var. cicla for feeding and egg laying. Only larval and adult experience acting in concert modified feeding behaviour, whereas oviposition preferences remained unaltered regardless of female previous experience. Offspring performance was higher on the preferred host (V. faba), indicating a preference–performance linkage for this leafminer. Experience on B. vulgaris var. cicla could not overcome oviposition preferences, which appear driven by fitness benefits for offspring.
