No abstract

The Indian meal moth Plodia interpunctella (Hübner) (Lepidoptera: Pyralidae) is a notorious stored-grain pest that can be found in most parts of China. The corpses, excretions, and other secretions of P. interpunctella larvae cause serious grain pollution, seriously affecting the nutritional and economic value of stored grain in China. To elucidate the potential distribution of P. interpunctella in China, we used the CLIMEX 4.0 model to project the potential distribution of the pest using historical climate data (1960–1990) and estimated future climate data (2030, 2050, and 2070). Under the historical climate situation, P. interpunctella was distributed in most areas of China, and its highly favorable habitats account for 48.14% of its total potential distribution. Because of temperature change in the future climate, suitable habitats will increase in the eastern part of Qinghai and will decrease in the mid-eastern, northeastern, and southeastern parts of China. Under these scenarios, the area of this pest’s highly favorable habitat will be reduced by 1.24 million km2, and its proportion will decrease to about 28.48%. These predicted outcomes will help to distinguish the impact of climate change on the potential distribution of P. interpunctella, thereby providing important information to design early forecasting and strategies to prevent pest harm to stored grain.

Compared to other insects, the pea aphid Acyrthosiphon pisum has a reduced immune system with an absence of genes coding for a lot of immunity-related molecules.Notably, nitric oxide synthase (NOS), which catalyses the synthesis of nitric oxide (NO), is present in the pea aphid. However, the role of NO in the immune system of pea aphid remains unclear. In this study, we explored the role of NO in the defence of the pea aphid against bacterial infections and found that the NOS gene of the pea aphid responded to an immune challenge, with the expression of ApNOS observably upregulated after bacterial infections. Knockdown of ApNOS using RNA interference or inhibition of NOS activity increased the number of live bacterial cells in aphids and the mortality of aphids after bacterial infection. Conversely, the increase in NO level in aphids using NO donor inhibited the bacterial growth, increased the survival of bacteriainfected aphids, and upregulated immune genes, such as Toll pathway and phagocytosis related genes. Thus, NO promotes immune responses and plays an important role in the immune system of pea aphid.

Plutella xylostella Linnaeus (Lepidoptera: Plutellidae) is one of the most important pests of cruciferous vegetables. Mechanically damaged Mentha spicata Linnaeus (Lamiales: Lamiaceae) strongly repels P. xylostella adults; however, the repellent mechanism remains unclear. In this study, the repellent mechanism was explored based on the electroantennogram (EAG) and behavioural responses of P. xylostella to volatiles from the damaged M. spicata. First, the active volatile compounds in the headspace volatiles of damaged M. spicata were identified by gas chromatography‐electroantennographic detection (GC‐EAD) and gas chromatography–mass spectrometry (GC–MS). Furthermore, the EAG and behavioural responses of P. xylostella to these compounds were investigated. The GC‐EAD results indicated that four compounds, 2,4‐dimethylheptane, 4‐methyloctane, 2‐methylnonane, and myrcene induced EAG responses in female antennae. 2‐methylnonane and myrcene elicited strong dose‐dependent EAG responses starting at a dose of 1 μg/μL. Choice tests in a four‐arm olfactometer showed significant repellent effects of the four compounds on P. xylostella adults at 100 μg/μL, and the repellent indices of 2,4‐dimethylheptane, 4‐methyloctane, 2‐methylnonane, and myrcene were 70.0%, 76.7%, 66.7%, and 73.3% to mated females, respectively. Finally, oviposition repellence assays showed that female adults were significantly repelled by these compounds, and the oviposition repellent index for myrcene was 23.9%. 2,4‐dimethylheptane, 4‐methyloctane, 2‐methylnonane, and myrcene mediate the repellence of wounded M. spicata to P. xylostella adults, suggesting that the four compounds contribute towards developing behavioural regulators of this important pest.