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Eucryptorrhynchus scrobiculatus and E. brandti (Coleoptera: Curculionidae) are destructive weevils on Ailanthus altissima in China. This study examined phototactic behaviour of E. scrobiculatus and E. brandti in response to eight light-emitting diodes (LEDs) in the laboratory and field. Effects of gender, starvation, and light and dark experience o...
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Context 1
... design of the phototactic behaviour octagonal response device was based on the habits of E. scrobiculatus and E. brandti adults. It was composed of eight small trapezoidal boxes (Figures 1 and 2). Each trapezoidal box was divided into three parts: a phototaxis area, a sensitive area, and a release area. ...
Context 2
... the mark-release-recapture test, the number of E. scrobiculatus and E. brandti adults trapped by violet (400-405 nm) traps is the largest. The average daily recapture E. scrobiculatus and E. brandti adults as the 13.7 and 14.0, followed by blue-violet (420-430 nm) light traps, recapture E. scrobiculatus and E. brandti adults as the 7.7 and 10.3, the other wavelength light traps trapped fewer insects (Figure 10). This is consistent with the results of the indoor selection test. ...
Citations
... Eucryptorrhynchus brandti was listed as a 'National Forest Quarantine Pests' in 2003 by the National Forestry Bureau in China due to its significant impact on A. altissima (State Forestry Administration of China, 2013). Traps have been developed recently to help control E. brandti, a trunk and branch feeder (Wen et al., 2018;, as well as the closely related root feeder, E. scrobiculatus (Motschulsky) (Ji et al., 2017b;Yang et al., 2019;. These two species often attack the same trees causing extensive damage that can lead to death (Hu et al., 2012;Yu et al., 2012). ...
... Moreover, the phototactic response of Thrips tabaci was shown to decrease at the middle light intensity, showing a wavy manner [25]. Interestingly, the phototactic behaviors of two weevils were not affected by the light intensity of 200-1000 lx, which was obviously different from the behaviors of other insects [24]. We used lx as the unit of light intensity in our experiments because it was more widely used in actual agricultural productions and was found in many studies (Table S1). ...
The fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), is an important migratory pest, causing great losses to agricultural production. Light trapping is a pesticide-free method for pest control and is influenced by many factors, especially wavelength and light intensity. In this study, a series of phototactic behavioral assays were carried out and the physical parameters were included to identify phototactic responses of S. frugiperda, with Helicoverpa armigera as control. It was found that S. frugiperda showed the highest average phototactic rate to blue light among five different LED lights. The phototactic rates of the two moths increased gradually with light intensity and were not obviously influenced by sex. In addition, the phototactic rate of S. frugiperda was significantly lower under a low light intensity of UV light than that of H. armigera, further confirmed by the indoor simulation experiment and EC50. According to the obtained parameters, the trapping distance of S. frugiperda to blue light was smaller than that of H. armigera to UV light. Therefore, we summarized a proposal of using blue light for light traps to control S. frugiperda, with a maximum distance of no more than 108 m. These results provide an experimental and theoretical basis for improving light-trapping techniques for managing S. frugiperda.
... After comparing the attraction rate with different light wavelengths, luminance intensities, and exposure times, they identified that yellow light with 80 lx luminous intensity and 90 min exposure was most attractive to western flower thrips. Wen et al. (2018) examined snout weevils (Eucryptorrhynchus scrobiculatus, Eucryptorrhynchus brandti) phototactic response to various wavelength lights with respect to starvation, light, and dark exposure times. Laboratory and field experiments were conducted and identified that violet (400 -410 nm) was most attractive to the weevils. ...
... Based on the insect location in the observation box, the phototaxis index was calculated using Equation (1). The greater the phototaxis index, the stronger the phototactic behavior (Wen et al., 2018). ...
Many nocturnal insect pests exhibit positive phototaxis to the artificial lights of a
certain wavelength. Identifying the phototaxis of pests is potentially useful for integrated
pest management. This study examined the phototactic response of two major insect
pests of paddy crops, yellow stemborer (YSB), Scirpophaga incertulas, and rice leaf
folder (LF), Cnaphalocrocis medinalis moths (Lepidoptera: Pyralidae). Four
monochromatic and three bichromatic surface mount device-light emitting diodes strips
- ultraviolet (365 ± 5 nm), violet (400 ± 5 nm), blue (465 ± 5 nm), green (525 ± 5 nm),
ultraviolet-violet (365 + 400 nm), violet-blue (400 + 465 nm), and ultraviolet-blue (365
+ 465 nm) are used for the study. Based on the laboratory and field experiments, YSB
moths showed the strongest attraction to ultraviolet (365 ± 5 nm) and LF attraction was
highest to violet (400 ± 5 nm) lights. In bichromatic phototactic experiments, both
species exhibited the strongest attraction to ultraviolet-violet (365 + 400 nm) lights. The
influence of luminance intensity, adaption time in darkness, and light exposure time on
the phototactic behavior of these moths are also tested. YSB and LF moths attraction rate
increased with an increase in luminance intensity and violet (400 ± 5 nm) at 70 lx showed
the strongest attraction. The light attraction rate of YSB was highest at 60 min of dark
adaptation and 45 min of light exposure time, LF has a higher attraction rate at 60 min
of dark adaptation and 30 min of light exposure time
... soil with a depth of 1-2 cm (Qin et al. 2020). Eucryptorrhynchus scrobiculatus, tree-of-heaven root weevil (TRW) and E. brandti, tree-of-heaven trunk weevil (TTW) are closely related species (Wen 2019). TRW overwinters as larvae and adults. ...
Dormancy is important for overwintering insects to resist and adapt to adverse conditions. Dormancy generally contains quiescence and diapause. Eucryptorrhynchus brandti Harold (Coleoptera: Curculionidae), tree-of-heaven trunk weevil (TTW), is a destructive pest and highly host-specific to Ailanthus altissima in China. TTW has one generation per year and overwinters as both larvae and adults. In this study, to examined dormancy type of adults and find a method to store overwintering adults, we collected adults from 20 October 2018 to 13 March 2019. We studied the behavior and reproductive development of adults under field cold conditions for 0 and 10 d and laboratory warm conditions for 5 and 10 d. We recorded developing eggs in females, and the clarity of the testis edge, the yellow point in the testis lobe, the ratio of the inner content in the accessory gland, and the accessory gland color in males. Adults transferred from the field to the laboratory had resumed reproductive development directly. Results indicated that the dormancy type of TTW adults was quiescence. Adults stored in the field were still in a dormant state and the field-storage method was effective. Current study provided basic data for controlling overwintering TTW adults and solve the storage of insect sources during the winter.
... Because of the differences in feeding preference of the two weevils, we selected the volatiles from different locations on Ailanthus altissima (Mill) Swingle according to Wen (2019). The nine compounds used for docking simulation were 1-hexanol (CAS number: 111-27-3), cis-3-hexen-1-ol (CAS number: 928-96-1), hexenyl acetate (CAS number: 3681-71-8), 2-tert-butyloxirane (CAS number: 2245-30-9), 2,5diethylphenol (CAS number: 876-20-0), alpha-farnesene (CAS number: 502-61-4), (1R)-(+)-alpha-pinene (CAS number: 7785-70-8), (-)-beta-caryophyllene (CAS number: 87-44-5), and beta-elemen (CAS number: 515-13-9). ...
The tree-of-heaven root weevil (Eucryptorrhynchus scrobiculatus) and the tree-of-heaven trunk weevil (Eucryptorrhynchus brandti) are closely related species that monophagously feed on the same host plant, the Ailanthus altissima (Mill) Swingle, at different locations. However, the mechanisms of how they select different parts of the host tree are unclear. As chemosensory systems play important roles in host location and oviposition, we screened candidate chemosensory protein genes from the transcriptomes of the two weevils at different developmental stages. In this study, we identified 12 candidate chemosensory proteins (CSPs) of E. scrobiculatus and E. brandti, three EscrCSPs, and one EbraCSPs, respectively, were newly identified. The qRT-PCR results showed that EscrCSP7/8a/9 and EbraCSP7/8/9 were significantly expressed in adult antennae, while EscrCSP8a and EbraCSP8 shared low sequence identity, suggesting that they may respond to different odorant molecule binding. Additionally, EbraCSP6 and EscrCSP6 were mainly expressed in antennae and proboscises and likely participate in the process of chemoreception. The binding simulation of nine volatile compounds of the host plant to EscrCSP8a and EbraCSP8 indicated that (1R)-(+)-alpha-pinene, (–)-beta-caryophyllene, and beta-elemen have higher binding affinities with EscrCSP8a and lower affinities with EbraCSP8. In addition, there were seven, two, and one EbraCSPs mainly expressed in pupae, larvae, and eggs, respectively, indicating possible developmental-related roles in E. brandti. We screened out several olfactory-related possible CSP genes in E. brandti and E. scrobiculatus and simulated the binding model of CSPs with different compounds, providing a basis for explaining the niche differentiation of the two weevils.
Eucryptorrhynchus scrobiculatus (Motschulsky) (Coleoptera: Curculionidae) is a notorious pest of Ailanthus altissima (Mill.) Swingle (Sapindales: Simaroubaceae). E. scrobiculatus adults typically aggregate under leaves and in soil crevices at the base of A. altissima in the field. We hypothesize that the environmental factors and conspecific signals determine their aggregation behavior. To test this, we investigated adult numbers in light-exposed and shaded areas of the sample trees and conducted experiments in both field and lab settings. Results revealed that (i) greater adult distribution in shaded areas; (ii) significant influence of temperature and illumination on aggregation tendency in the field; (iii) no gender-based difference in aggregation degree and maximum aggregation between light and dark; (iv) the host plant triggering the aggregation tendency, negatively affected in the absence; (v) the aggregation tendency of E. scrobiculatus weakened with the temperature gradually changing to ordinary temperature; and (vi) mutual attraction and chemical attraction between males and females. Thus, the aggregation behavior was influenced by factors including temperature, light intensity, host plant, and conspecific signals, but light’s role was not obvious in the lab.
Phototaxis, a visual behaviour of insects toward light, is used to monitor and control insect pests worldwide. However, certain pest control practices have raised concerns because of the unintended elimination of non-target insects. Additionally, artificial lighting has expanded owing to urbanization. We investigated the phototactic behaviour of the dominant predatory beetle, Propylaea japonica. We explored its visual responses to seven monochromatic lights at 365–655 nm wavelength and various intensities at the preferred wavelength. The highest response occurred at 365 nm (ultraviolet), followed by 465 and 525 nm. When only the light intensity at 365 nm was varied (10, 100, and 300 lux), the response to 365 nm at 10 lux decreased, and the strongest response shifted to 420 nm (violet), but the preference increased with elevated light intensity at 365 nm. Examining behavioural responses to light intensities at 1–5000 lux (365 nm), a preference for 1000–5000 lux was observed, although mixed populations (males and females) exhibited increased responses at 10–100 lux. Our results indicate a preference for shorter wavelengths (365 nm) across different light environments (wavelength) and underscore the role of light intensity in influencing wavelength selection in P. japonica. This study provides insights for the development of light sources for insect monitoring and pest control.
Arthropods use a variety of environmental cues to navigate between and locate hosts. In agricultural systems, clarifying the relevant cues and their effects on arthropod behavior can inform management practices to reduce or inhibit the activity of arthropod pests. The lesser mealworm Alphitobius diaperinus (Panzer) is a ubiquitous arthropod pest of broiler house chicken production, and while the patterns of movement and behavior of A. diaperinus are well documented, the specific environmental factors that govern these patterns are not known. We conducted behavioral assays testing the response of A. diaperinus adults and larvae to different wavelengths of light and to the presence of water. Alphitobius diaperinus displayed a significant repulsion from white, green, red, and blue light, while larvae consistently sought shelter and displayed no behavioral change in response to light. Dehydrated adult beetles displayed an attraction to water while hydrated beetles displayed a repulsion to water. Regardless of the availability of water, dehydrated beetles displayed a reduced repulsion from light. Taken together, these results indicate that A. diaperinus will hide from sources of light unless they are dehydrated. Knowledge of the environmental cues that influence the behavior of A. diaperinus could be used to improve methods of trapping, monitoring, and controlling populations of A. diaperinus in experimental and commercial settings.
Simple Summary
Eucryptorrhynchus scrobiculatus and its related species Eucryptorrhynchus brandti together damage Ailanthus altissima and Ailanthus altissima ‘Qiantou’. E. scrobiculatus possesses a large compound eye area and a higher number of ommatidia than E. brandti. Each ommatidium of E. scrobiculatus and E. brandti consists of a cornea, a crystalline cone, eight retinal cells, and its semi-fused rhabdom. The internal structure, including the cornea and rhabdom, of E. scrobiculatus is larger than that of E. brandti. Light/dark adaptational changes affect cone length, the position of pigment grains, and the cross-sectional area of the rhabdoms.
Abstract
Eucryptorrhynchus scrobiculatus and E. brandti are the main borers of Ailanthus altissima, causing serious economic and ecological losses. The external morphology and internal ultrastructure of the compound eyes of two related weevils were investigated with light microscopy, scanning electron microscopy, and transmission electron microscopy. E. scrobiculatus and E. brandti possess a pair of reniform apposition compound eyes and contain about 550 ommatidia per eye. The interommatidial angle of E. scrobiculatus and E. brandti are 7.08 ± 0.31° and 4.84 ± 0.49°, respectively. The corneal thickness, rhabdom length, and ommatidium length of E. scrobiculatus are significantly greater than those of E. brandti. Under light-adapted conditions, the pigment granules are mainly distributed at the junction of the cone and the rhabdom, and the diameter and the cross-sectional area of the middle end of the rhabdom is increased in the two weevil species. Under dark-adapted conditions, the pigment granules shift longitudinally and are evenly distributed on both sides of the cone and the rhabdom, and the diameter and cross-sectional area of the middle end of the rhabdom are decreased. The discrepancy in visual structure is beneficial for adaptation to niche differentiation of the two related species. The present results suggest that the two weevils possess different visual organ structures to perceive visual information in the external environment.
The tree-of-heaven trunk weevil, Eucryptorrhynchus brandti (Harold) (Coleoptera: Curculionidae), is one of the most harmful pests that damage the tree of heaven, Ailanthus altissima Swingle (Sapindales: Simaroubaceae). Aggregation behavior tests of E. brandti adults were conducted in laboratory conditions. The effects of temperature and light on the aggregation behavior of adults were tested, and the effect of sex and host was conducted with binomial choice experiments. The results showed that (1) the adults aggregate in both light and dark environments but preferred the dark environment, (2) temperature can drive the aggregation of E. brandti adults, (3) host plants could trigger E. brandti adults’ aggregation behavior, which is probably related to phytochemicals and insect feeding and localization, (4) there was mutual attraction of males and females and chemical attraction of crude intestinal extracts of males and females, and (5) aggregation behavior of E. brandti adults may also be related to the mediating of physical signals in insects. In this study, aggregation behavior can help us understand conspecific interactions and discover some strategies for effective control.
