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Background: Global climate change is causing an increase in extreme high temperatures (EHTs), which subject insects to unprecedented stress. Behavior plasticity in response to EHTs, particularly oviposition behavior, is important for the persistence and outbreak of insect populations. Investigating the plasticity of oviposition behavior and its underlying mechanisms has theoretical importance to pest management, but knowledge gaps still remain. Results: Herein, we characterized the reproductive traits of Monochamus alternatus, a dominant insect vector of the destructive pine wilt disease, including oviposition behavioral patterns, fecundity, offspring fitness and sperm viability, under simulated heatwave conditions in the laboratory. The results showed that (i) EHTs induced a novel oviposition behavior, whereby females deposited multiple eggs into a single groove rather than laying one egg per groove under normal condition; (ii) EHTs exerted stage‐ and sex‐specific effects on fecundity, offspring fitness and sperm viability; and (iii) there was a significant correlation between frequency of the novel oviposition strategy and sperm viability. Conclusion: We hypothesized that this beetle pest has the ability to flexibly shift towards a low‐cost oviposition strategy to counteract the fitness costs caused by heat stress. Taken together, these findings provide a theoretical foundation for personalized pest management strategies in the context of climate change. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The longhorned beetle Aromia bungii (Coleoptera: Cerambycidae) is a major pest of stone fruit trees in the genus Prunus, including cherries, apricots, and peaches. Its native range includes China, Korea, Mongolia, and eastern Russia, but it has recently invaded and become established in several countries in Europe, and Japan, and it has been intercepted in shipments coming into North America and Australia. Here, we report the identification of its male-produced aggregation pheromone as the novel compound (E)-2-cis-6,7-epoxynonenal. In field trials in its native range in China, and in recently invaded areas of Japan, the pheromone attracted both sexes of the beetle. Thus, the pheromone should find immediate use in worldwide quarantine surveillance efforts to detect the beetle in incoming shipments. The pheromone will also be a crucial tool in ongoing efforts to eradicate the beetle from regions of the world that it has already invaded.

The Asian wood-boring beetle Anoplophora chinensis (Forster) (Coleoptera: Cerambycidae) is an important pest of hardwood trees in its native range, and has serious potential to invade other areas of the world through worldwide commerce in woody plants and wood products. This species already has been intercepted in North America, and is the subject of ongoing eradication efforts in several countries in Europe. Attractants such as pheromones would be immediately useful as baits in traps for its detection. Because long-range pheromones are frequently conserved among closely related species of cerambycids, we evaluated two components of the volatile pheromone produced by males of the congener A. glabripennis (Motschulsky), 4-(n-heptyloxy)butan-1-ol and 4-(n-heptyloxy)butanal, as potential pheromones of A. chinensis. Both compounds subsequently were detected in headspace volatiles from male A. chinensis, but not in volatiles from females. Only 4-(n-heptyloxy)butanol elicited responses from beetle antennae in coupled gas chromatography-electroantennogram analyses, and this compound attracted adult A. chinensis of both sexes in field bioassays. These data suggest that 4-(n-heptyloxy)butan-1-ol is an important component of the male-produced attractant pheromone of A. chinensis, which should find immediate use in quarantine monitoring for this pest.

Conifers have evolved sophisticated terpenoid defenses for protection against herbivores and pathogens. Pinus massoniana Lamb. is the most widely distributed pioneer afforestation and resin tree species in China, but is seriously harmed by pine wilt disease. Monochamus alternatus is the main vector of pine wilt disease in China. Monoterpenes, sesquiterpenes and diterpenes, the main secondary defensive compounds of P. massoniana, are catalyzed by different terpene synthases (TPSs), which participate in the important defense pathways against external biotic and abiotic stresses. Here, we aimed to identify the terpene synthases (TPSs) in P. massoniana, responding to the feeding of M. alternatus, and to characterize the functions and products of the mono-TPSs. We identified six differentially expressed TPS genes in the P. massoniana fed upon by M. alternatus, including four mono-TPS and two sesqui-TPS genes. The functions of the four mono-TPSs were verified by analysis of the main product and by-products of these mono-TPSs. (+)-α-Pinene, (−)-α-pinene, and limonene were the major products of TPS (+)-α-pinene, TPS (−)-α-pinene, and TPS limonene, respectively, but TPS (−)-β-pinene only catalyzed a trace amount of (−)-β-pinene in the products. Our findings shed light on the potential relationships between the structure of terpene synthases and their corresponding products. [ABSTRACT FROM AUTHOR]

Plants play an important role in interactions between insect herbivores and their pathogens. The ability of host plants to modify the infectivity of entomopathogens in herbivorous insects has been widely documented. However, the plants' nutrients have always been neglected as a factor contributing to variation in the susceptibility of insect herbivores to entomopathogens. The fall-webworm (FWW), Hyphantria cunea Drury, is a typical polyphagous caterpillar, and the Hyphantria cunea nucleopolyhedrovirus (HycuNPV) is a distinctly specialized baculovirus for the FWW, which is safe for other organisms and has been effectively used as a biological insecticide against H. cunea in China. In this study, we investigated the nutrient components of four host plant species, i.e., Prunus serrulate, Cerasus serrulate, Camptotheca acuminata, and Populus deltoides, and their effects on the susceptibility of H. cunea larvae to HycuNPV. The HycuNPV-infected larvae fed on P. deltoides leaves exhibited higher survival rates, longer survival times, more food intake, and gained larger body size. These biological parameters were positively correlated with the nitrogen components of host plant leaves. Moreover, the larval antioxidant enzymes exhibited different responses to HycuNPV. HycuNPV infection significantly triggered the catalase (CAT) and prophenoloxidase (PPO) enzyme activity levels of H. cunea larvae. The uninfected larvae fed on poplar leaves induced a robust increase in the POD activity, which could scavenge extra reactive oxygen species and provide a protective effect against the HycuNPV. In conclusion, the plant-mediated effects of HycuNPV on the FWW have been investigated in this study. The nitrogen content in dietary was an essential factor in determining the insect herbivore susceptibility to entomopathogenic viruses, and it helped explain variations in the susceptibility of pests to the entomopathogenic viruses and aid in developing more robust tolerance monitoring assays in the lab that reflect the performance of pests in the field. [ABSTRACT FROM AUTHOR]

Hyphantria cunea Drury (Lepidoptera: Erebidae) is a quarantine pest in China that can cause damage to hundreds of plants. As biological control agents, Nuclear Polyhedrosis Virus (NPV) and Bacillus thuringiensis Berliner (Bacillales: Bacillaceae) (Bt) are commonly used to inhibit the prevalence of H. cunea. To investigate the role of midgut bacteria in the infection of NPV and Bt in H. cunea , we performed a series of tests, including isolating the dominant culturable bacteria in the midgut, eliminating intestinal bacteria, and respectively inoculating the dominant strains with NPV and Bt for bioassay. Two dominant bacteria, Klebsiella oxytoca Lautrop (Enterobacterales: Enterobacteriaceae) and Enterococcus mundtii Collins (Lactobacillales: Enterococcaceae), in the midgut of H. cunea were identified, and a strain of H. cunea larvae without intestinal bacteria was successfully established. In the bioassays of entomopathogen infection, K. oxytoca showed significant synergistic effects with both NPV and Bt on the death of H. cunea. In contrast, E. mundtii played antagonistic effects. This phenomenon may be attributed to the differences in the physico-chemical properties of the two gut bacteria and the alkaline environment required for NPV and Bt to infect the host. It is worth noting that the enhanced insecticidal activity of K. oxytoca on NPV and Bt provides a reference for future biological control of H. cunea by intestinal bacteria. [ABSTRACT FROM AUTHOR]