To reveal the nature of locusts’ visual reaction when stimulated by light, and to clarify the regulation characteristics of locusts’ phototactic visual physiology and obtain good spectral light features for locusts’ phototactic action, this study investigated locusts’ visual spectrum response by characterizing their photoreceptive reaction to LED light using an AvaSpec fiber-optic spectrometer system. Locusts’ phototactic response to spectral light was compared using this system. The results showed that locusts’ visual reaction characterization presents a photo-induced vision spectrum effect and that by offsetting the main wavelength of light and the spectral peak intensity, a time-varying bio-regulation effect emerges. In addition, locusts’ visual regulation ability to UV light is higher than that to violet light, whereas their reaction intensity is lower than to violet light, and the visual bio-regulatory force of locusts’ visual system absorbing orange light to react sensitively becomes gradually higher than when absorbing green light as time goes on. Moreover, corresponding to nominal illumination with the same radiant energy and a visual spectrum response stimulated by UV, violet, orange, and green light, it appears that the visual spectrum window is symmetrical around 382 nm, 400 nm, 602 nm, and 530 nm, respectively, with no obvious difference between spectral amplitudes and having a time-varying incremental characteristic with amplitude peak width. This indicates that the stimulus intensity of UV, violet, orange, and green light exceeds locusts’ visual tolerance, causing them to generate regulation inactivation as a visual physiological reaction, whereas the visual window response effect stimulated by UV light presents an illumination timeliness effect. Simultaneously, time-varying characteristics of locusts’ bio-behavior intensity show that light intensity can make up for locusts’ visual sensitivity differences at various spectral wavelengths. Presented with differential response time, photosensitive behavior intensity, and induction effect induced by orange light, time is superior for orange light, the stimulation effect caused by violet light is the strongest, and the phototactic synergy effect caused by UV light is the best. Keywords: Locusta migratoria manilensis, photoreceptive spectrum effect, visual reaction intensity, photosensitive activity effect, spectral illumination DOI: 10.25165/j.ijabe.20211402.4758 Citation: Liu Q H, Jiang Y L, Miao J, Gong Z J, Li T, Duan Y, et al. Photoreceptive reaction spectrum effect and phototactic activity intensity of locusts’ visual display characteristics stimulated by spectral light. Int J Agric & Biol Eng, 2021; 14(2): 19–25.

Visual response effects of western flower thrips manipulated by different light spectra

Holotrichia parallela is among the world’s most destructive pests. For accurate qPCR and gene expression studies, the selection of stable and appropriate reference genes is crucial. However, a thorough evaluation of potential reference genes for use in H. parallela research is lacking. In this study, 11 reference genes (GAPDH, RPL32, RPL7A, RPS18, RPL13a, RPL18, Actin, RPS7, RPS3, VATB,and EF1A) were evaluated under different biological conditions and environmental stresses. The stability of 11 potential reference gene transcripts was evaluated through various computational tools, including geNorm, BestKeeper, NormFinder, theΔCt method, and the RefFinder program. Under various developmental stages and RNAi conditions, RPL18 and RPL13a exhibited the greatest stability. RPL13a, RPL18, and RPL32 were the most stable genes in both male and female adults. Under differing tissue conditions, RPL13a and RPS3 stood out as the most reliable. Moreover, under varying photoperiod conditions, RPL13a, RPS3 and RPL32 were the most stable genes. Lastly, Actin and RPL13a were the most stable genes across different temperatures. These findings offer essential criteria for selecting suitable reference genes across diverse experimental settings, thereby establishing a solid basis for accurate gene expression studies in H. parallela using RT-qPCR.

Holotrichia parallela is an important plant pest. Comparative feeding experiments showed that the egg production, oviposition duration and survival rate of H. parallela beetles were significantly higher when they fed on elm leaves than when they fed on willow or purpus privet leaves. RNA sequencing was used to determine transcriptomic changes associated with oviposition. Comparative transcriptome analysis revealed that the beetles that fed on elm and willow had a total of 171 genes with differential expression. When the beetles fed on elm and purpus privet, 3568 genes had differential expression. The vitellogenesis, ovarian serine protease, odorant-binding proteins, acyl-CoA synthetase and follicle cell proteins were commonly upregulated genes in elm-fed beetles compared with those fed on willow/purpus privet leaves. The involvement of the follicle cell protein 3C gene in the regulation of oviposition was confirmed using RNA interference. The results provide insights into the molecular mechanisms underlying oviposition in H. parallela feeding on different host plants. This study also describes a method for identifying potentially effective genes for pest control.

Light is one of the key environmental factors for insects to survive. Artificial light sources different from natural environmental light can cause light stress in insects. Yellow and green light stress can interfere with the diurnal rhythm of nocturnal moths and their mating, oviposition, and adult longevity. The scarabaeid beetles Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky are widely distributed, and they are very harmful underground pests. In order to clarify the effects of light stress on their behaviors, individuals of both species were exposed to yellow light (565-585 nm) and green light (525-545 nm), with different light intensity gradients of yellow light in a laboratory setting. The short-term light stress treatment of A. corpulenta and H. parallela was carried out at night. The number of beetles emerging per half an hour was recorded, and mating pairs and feeding activity in 24 h were counted. The results showed that yellow and green light stress significantly changed the rhythm and reduced the rate of beetle emergence in the two beetle species investigated. Also, the peak emergence activity was delayed and the feeding and mating activities were significantly reduced. When treated with different intensities of yellow light, it was found that the rate of emergence of A. corpulenta under 10 lx was close to the control groups. The rate of emergence in H. parallela was significantly lower than the control groups before 0:00, in the 60 lx and 110 lx treatment groups, but after 0:00, the emergence rate of H. parallela was significantly higher in the 60 lx and 110 lx treatment groups than other treatments. However, the emergence rhythms in the three light intensity treatment groups are basically the same as in the control groups. The feeding amount and mating beetles in the three light intensity treatment groups were significantly lower than in the control groups. There were no significant differences in the three treatments. The results show that light stress above 10 lx significantly interferes with the behavioral activities of the two beetle species, investigated. This study provides a new approach for a light control technology for nocturnal beetle pest species. Keywords: yellow and green light, Anomala corpulenta Motschulsky, Holotrichia parallela Motschulsky, emergence rhythm, feeding, mating DOI: 10.25165/j.ijabe.20231601.7639 Citation: Jiang Y L, Huang Q Y, Wei G S, Gong Z J, Li T, Miao J, et al. Effects of yellow and green light stress on emergence, feeding and mating of Anomala corpulenta Motschulsky and Holotrichia parallela Motschulsky (Coleoptera: Scarabaeidae). Int J Agric & Biol Eng, 2023; 16(1): –.

Anomala corpulenta (Motschulsky, 1854) (Coleoptera: Scarabaeidae), an important agricultural and forestry pest, is a beetle widely distributed in many countries, inflicting damage on numerous crops. Given the limited selectivity of commonly used light trapping devices for insects and their potential adverse effects on the ecological environment, there is a pressing need for innovative light control methods. This study investigates the effects of continuous exposure to yellow light on the behavioral activities of A. corpulenta adults, which are nocturnal. The experimental setup comprised a light experimental group (exposed continuously to yellow light at wavelengths of 565–585 nm and intensities of 30–40 lx at night) and a control group (kept in a dark room). Observations were made on emergence, mating, feeding, and mortality. Results showed that continuous exposure to yellow light significantly alters the emergence rhythm of A. corpulenta, leading to delays and dispersions in peak emergence, with emergence occurring during the light period. The emergence rates varied significantly from the control group during specific periods, and the overall emergence rate was notably affected, with female insects exhibiting greater sensitivity. Furthermore, food consumption and the number of mating pairs were significantly lower compared to the control group. Continuous exposure to yellow light also influenced the longevity of A. corpulenta; in the mixed test group, female insects had a lifespan of 20 days, while males lived for 18 days. In the sexually isolated test group, both sexes died within 16 days, with the survival rates of the experimental group being lower than those of the control group on certain days. This study concludes that continuous exposure to yellow light significantly modifies the emergence rhythm of A. corpulenta, while reducing the emergence rate, total food intake, and the number of mating pairs. Notably, in the mixed-sex test group, the survival probability of females in the experimental group was significantly lower than that of the control group. These findings provide a theoretical foundation for the light control of A. corpulenta and contribute to the field of insect visual ecology.