Search Results (11)

Phthorimaea absoluta (Meyrick) is an invasive pest that has caused damage to tomatoes and other crops in China since 2017. Pest control is mainly based on chemical methods that pose significant threats to food safety and environmental and ecological security. Light-induced control, a green prevention and control technology, has gained attention recently. However, current light-trapping technology is non-specific, attracting targeted pests alongside natural enemies and non-target organisms. In this study, we characterized the phototactic behavior of tomato leaf miners for the development a specific light-trapping technology for pest control. In situ hybridization revealed opsin expression throughout the body. Furthermore, we investigated the tropism of pests (wild T. absoluta, Toxoptera graminum, and Bemisia tabaci) and natural enemies (Nesidiocoris tenuis and Trichogramma pintoi) using a wavelength-lamp tropism experiment. We found that 365 ± 5 nm light could accurately trap wild P. absoluta without trapping natural enemies and other insects. Finally, we analyzed the phototactic behavior of the mutant strains LW2^(−/−) and BL^(−/−). LW2 and BL mutants showed significant differences in phototactic behavior. The LW2^(−/−) strain was attracted to light at 390 ± 5 nm and the BL^(−/−) strain was unresponsive to any light. Our findings will help to develop specific light-trapping technology for controlling tomato leaf miners, providing a basis for understanding pest population dynamics and protecting crops against natural enemies. Full article

The phototactic behavior of insects is commonly used to manage pest populations in practical production. However, this elusive behavior is not yet fully understood. Investigating whether the opsin genes play a crucial role in phototaxis is an intriguing topic. Vespinae (Hymenoptera: Vespidae) are a common group of social wasps that are closely associated with human activities. Efficiently controlling wasp populations while maintaining ecological balance is a pressing global challenge that still has to be resolved. This research aims to explore the phototactic behavior and key opsin genes associated with Vespinae. We found significant differences in the photophilic rates of Vespula germanica and Vespa analis under 14 different light conditions, indicating that their phototactic behavior is rhythmic. The results also showed that the two species exhibited varying photophilic rates under different wavelengths of light, suggesting that light wavelength significantly affects their phototactic behavior. Additionally, the opsin genes of the most aggressive hornet, Vespa basalis, have been sequenced. There are only two opsin genes, one for UV light and the other for blue light, and Vespa basalis lacks long-wavelength visual proteins. However, they exhibit peak phototaxis for long-wavelength light and instead have the lowest phototaxis for UV light. This suggests that the visual protein genes have a complex regulatory mechanism for phototactic behavior in Vespinae. Additionally, visual protein sequences have a high degree of homology among Hymenoptera. Despite the hypotheses put forward by some scholars regarding phototaxis, a clear and complete explanation of insect phototaxis is still lacking to date. Our findings provide a strong theoretical basis for further investigation of visual expression patterns and phototactic mechanisms in Vespinae. Full article

The positive phototaxis showed by adults of some pestiferous chironomid species, annoying to waterfront residents and businesses, was investigated at Lake Trasimeno (Italy) to develop a strategy against their massive swarms. Two experimental devices (ChiroTraps), located at Passignano sul Trasimeno (PA) and at Sant’Arcangelo (SA), were employed in 2019 and 2020. The total biomass attracted by the traps amounted to 6498.78 g at PA and to 8597.05 g at SA. Chironomids biomass constituted 99.66% and 96.59% of the biomass in these sites, respectively. Only a few specimens of other fauna except chironomids were found at PA. In contrast, the values at SA were considerable, being 91- and 35-fold (number of taxa and weight, respectively) higher than in PA. These results demonstrated that exploiting the light attraction behaviour of adult chironomids is an efficient method for managing their pestiferous populations, thereby reducing the necessity of using insecticides. By comparing the biodiversity in the two sites, it was evident that the differences were linked primarily to the environmental conditions. Finally, it is suggested that light trapping systems should be located in urban centres or floated on the lake surface to maximise the efficiency of trapping chironomids and minimising the impact on biodiversity. Full article

Light traps play a crucial role in monitoring pest populations. However, the phototactic behavior of adult Asian longhorned beetle (ALB) remains enigmatic. To provide a theoretical foundation to select the suitable light emitting diode (LED)-based light sources used for monitoring ALB, we compared the effect of exposure time on the phototactic response rates of adults at wavelengths of 365 nm, 420 nm, 435 nm, and 515 nm, and found that the phototactic rate increased gradually when the exposure time was prolonged, but there was no significant difference between different exposure times. We evaluated the effect of diel rhythm and found the highest phototactic rate at night (0:00–2:00) under 420 nm and 435 nm illumination (74–82%). Finally, we determined the phototactic behavioral response of adults to 14 different wavelengths and found both females and males showed a preference for violet wavelengths (420 nm and 435 nm). Furthermore, the effect of the light intensity experiments showed that there were no significant differences in the trapping rate between different light intensities at 120 min exposure time. Our findings demonstrate that ALB is a positively phototactic insect, showing that 420 nm and 435 nm are the most suitable wavelengths for attracting adults. Full article

Tuta absoluta (Meyrick), a leafminer that damages tomato leaves, terminal buds, flowers, and fruits, is a destructive tomato pest and is responsible for 80–100% of tomato yield losses globally. Different insect species have different courtship responses and phototropic flight rhythms. Improving the trapping effects of the sex pheromone and light traps is important for constructing an IPM system for T. absoluta. The present study explored the hourly distribution of T. absoluta adults caught by the sex pheromone (on the ground) and UV light (380 nm) traps in greenhouses over 24 h. The responses of males to sex pheromone (false female) lures were detected at dawn and early morning. The responses lasted for 3 h, from 05:30 (1 h before sunrise) to 08:30 (2 h after sunrise), and 95.8% of the males were caught during this period. The peak of the male responses to the sex pheromone was detected at 07:30 (from 06:30 to 07:30, 1 h after sunrise), and 80.8% of the males were caught during this period. The flight of male (proportion of 54.3%) and female (45.7%) adults toward the UV light traps occurred from 19:30 (time of sunset) to 06:30 (time of sunrise), lasted for 11 h, and exhibited a scotophase rhythm; 97.4% of the adults were caught during this period. The peak of adults flying toward the UV light traps occurred at 21:30 (from 20:30 to 21:30, 2 h after sunset). The rhythms of males’ responses to the sex pheromone and of the adults’ flight toward the UV lights can help to reveal the mechanisms of chemotactic and phototactic responses and may play a significant role in constructing an IPM system for this pest. Full article

An unattended pest control system was developed to eliminate whiteflies (Bemisia tabaci) that settled on greenhouse tomato plants. The system exploited the whitefly’s habit of flying up from a plant that was mechanically tapped and then heading toward yellow objects. Remote-controlled dollies with arms that tapped plants and yellow-colored double-charged dipolar electric field screens (YDD-EFSs) (oppositely electrified transparent insulator tubes filled with yellow-colored water) attracted and trapped the whiteflies. The whiteflies flew up when the plants were mechanically tapped with the dolly’s arms during reciprocating movements and were subsequently trapped by YDD-EFSs that were automatically translocated to the target plants. The system was applied to rows of whitefly-infested tomato plants. Almost all whiteflies transferred to plants were successfully recovered by two dollies moving on either side of the plants, approaching all plants individually (via programmed movement). In summary, we present an efficient unattended method for controlling whiteflies on tomato plants in greenhouses. Full article

Electrostatic devices generating an electric field (EF) are promising tools for greenhouse tomato cultivation. In these devices, an EF is generated in the space surrounding an insulated conductor (IC) that is charged by a voltage generator. Thus, a physical force is exerted on any insect that enters the EF, as a negatively charged IC (NC-IC) pushes a negative charge (free electrons) out of the insect body. The insect is polarized positively to be attracted to the NC-IC, and a grounded metal net (G-MN) repels the insect. This dual function of the apparatus (insect capture and repulsion) is the core of the electrostatic pest-exclusion strategy. In this study, we applied various innovative EF-based devices to evaluate their efficacy in greenhouse tomato cultivation. Our objective was to determine the optimal apparatus for simple, inexpensive construction by greenhouse workers. The results of this study will contribute to the development of sustainable pest-management protocols in greenhouse horticulture. Full article

The phototaxis of insects is closely related to light source factors, such as spectrum and light intensity. The cane grub, Exolontha castanea Chang (Coleoptera: Melolonthidae), is an important underground pest of sugarcane in Guangxi province of China. To clarify the effect of spectral sensitivity and light intensity response on the phototactic behavior of E. castanea, the phototactic behavior responses of male and female adults to 13 monochromatic lights in the wavelength range of 365–630 nm and different light intensities were measured. We found that both male and female adults had positive phototaxis to 13 monochromatic lights. The phototactic response rate of males and females at ultraviolet and violet light was the highest in the wavelength range of 365–420 nm. Among them, the most sensitive spectrum of females and males was at 365 nm and 420 nm, respectively. From the intensity response of phototactic behavior to different spectrum, the G1 (strong phototaxis) response rates of females at 365 nm and males at 420 nm were the highest. In addition, the phototactic response rate of females and males increased with the light intensity, showing a significant positive correlation. This study showed that the spectrum and light intensity were the key factors affecting the phototactic behavior of E. castanea. The sensitive spectrum of males and females were different, with a similar trend in phototaxis. Full article

Our aim was to develop an electrostatic apparatus to lure and capture silverleaf whiteflies (Bemisia tabaci), vegetable leafminers (Liriomyza sativae), and western flower thrips (Frankliniella occidentalis) that invade tomato greenhouses. A double-charged dipolar electric field producer (DD-EFP) was constructed by filling water in two identical transparent soft polyvinyl chloride tubes arrayed in parallel with fixed separation, and then, inserting the probes of grounded negative and positive voltage generators into the water of the two tubes to generate negatively and positively charged waters, respectively. These charged waters electrified the outer surfaces of the opposite tubes via dielectric polarization. An electric field formed between the oppositely charged tubes. To lure these phototactic insects, the water was colored yellow using watercolor paste, then introduced into the transparent insulator tubes to construct the yellow-colored DD-EFP. This apparatus lured insects in a manner similar to commercially available yellow sticky traps. The yellow-colored DD-EFP was easily placed as a movable upright screen along the plants, such that invading pests were preferentially attracted to the trap before reaching the plants. Furthermore, pests settling on the plants were attracted to the apparatus, which used a plant-tapping method to drive them off the plants. Our study provided an experimental basis for developing an electrostatic device to attract and capture insects that enter greenhouses. Full article

Phototactic and polarotactic aquatic insects, such as mayflies, can be drawn to electric lighting on bridges at night. Past research investigating the effect of light intensity, polarization, and spectrum on mayflies suggests that a combination of different techniques can reduce the number of mayflies attracted to bridges. Here, various lighting strategies are systematically tested on Veterans Memorial Bridge in Pennsylvania to investigate the effect of lighting on mayflies and address safety concerns caused by their mass crowding. Isolated trials on different parts of the bridge tested the effectiveness of correlated color temperature, chromaticity, ultraviolet radiation, shielding, and polarization. Results indicate that mayflies were more attracted to ultraviolet radiation, blue and green light, and polarized light than other lighting conditions. Shielding was minimally effective in reducing the number of mayflies on the bridge when supported by the change in light source spectrum. While the correlated color temperature did not result in a statistically significant impact, the spectral power distribution of the light sources was a major influencer for mayfly activity. Future research should investigate the effect of radiant intensity and timing on mayfly activity. Smart solid-state lighting systems and controls can also be used to adjust the light levels when needed to reduce adverse effects on aquatic insects and aid traffic safety. Full article

Lepidopteran larvae upon infection by baculovirus show positive photo-tactic movement during tree-top disease. In light of many insects exploiting specific spectral information for the different behavioral decision, each spectral wavelength of light is an individual parsimonious candidate for such behavior stimulation. Here, we investigated the responses of third instar Helicoverpa armigera larvae infected by Helicoverpa armigera nucleopolyhedrovirus (HearNPV) to white (broad-spectrum), blue (450–490 nm), UVA (320–400 nm), and UVB (290–320 nm) lights for the tree-top disease. Our findings suggest that tree-top phenomenon is induced only when the light is applied from above. Blue, white and UVA lights from above induced tree-top disease, causing infected larvae to die in an elevated position compared to those larvae living in the complete dark. In contrast, UVB from above did not induce tree-top disease. Blue light exerted the maximum photo-tactic response, significantly (p < 0.01) higher than white light. The magnitude of the response decreased with decreasing wavelength to UVA, and no response at UVB. Our results suggested that the spectral wavelength of the light has a significant effect on the induction of the tree-top disease in H. armigera third instar larvae infected with HearNPV. Full article