Dongping Chen

As a new vector insect of pine wood nematodes in China, the Monochamus saltuarius (Coleoptera: Cerambycidae) vectors pine wilt nematodes into healthy pine trees through feeding and oviposition, resulting in huge economic losses to forestry. A promising control strategy is to develop safe and efficient attractants. This study aims to screen for the key active volatiles of Pinus koraiensis (Pinales: Pinaceae), Pinus tabuliformis (Pinales: Pinaceae), and Picea asperata (Pinales: Pinaceae) that can attract M. saltuarius, and to study the synergistic attraction of the main attractant plant volatiles with ethanol and insect aggregation pheromones. The preference of M. saltuarius for three hosts is P. koraiensis > P. tabuliformis > Picea asperata. We detected 18 organic volatiles from three host plants. Through EAG assays and indoor Y-tube behavioral experiments, 3-carene, (-)-camphor, β-pinene, α-phellandrene, terpinolene, α-pinene, D-limonene, and myrcene were screened to have attractive effects on M. saltuarius. We found that 3-carene, β-pinene, and α-pinene are the most attractive kairomones in field experiments, which may play a crucial role in the host localization of M. saltuarius. Ethanol has a synergistic effect on the attractant activity of 3-carene and β-pinene, and the synergistic effect on β-pinene is the best. The mixture of ethanol, 2-undecyloxy-1-ethanol, and ipsdienol can significantly enhance the attraction effect of β-pinene on M. saltuarius. These new findings provide a theoretical basis for the development of attractants for adult M. saltuarius and contribute to the green control of M. saltuarius.

Objective Bruceine D is a botanical pesticide isolated from the traditional Chinese medicine Brucea javanica（Linn.）Merr. It has good insecticidal activity and can effectively inhibit the growth of various insect pests including Drosophila melanogaster.However，the toxicology mechanism is limited.This study aims to explore the toxic mechanism of BD of inhibiting the growth of D. melanogaster. Method Using D. melanogaster as the research object.End 2nd instar larvae of D. melanogaster were treated artificial diet containing 20 μg/g BD.The effects of BD on body weight，midgut and fat body of D. melanogaster after treatment for 24 h and 48 h were studied.We performed experiments of immunocytochemistry，western blot，quantitative real time PCR to investigate whether BD can induce midgut apoptosis，affect the growth of fat body cells and affect nutritional signaling pathway in D. melanogaster. Result It was found that 20 μg/g BD can significantly inhibit weight gain and growth of adipose somatic cells of D. melanogaster.Meanwhile，the cell nucleus of the fat body was wrinkled and apoptosis was induced in midguts after 48 h BD treatment.In addition，the experiment of qPCR and western blot showed that BD significantly up-regulated the transcription levels of insulin signaling pathway negative regulatory genes 4EBP and InR of the insulin signaling pathway，while down-regulating the phosphorylation level of 4EBP of fat body，which inhibited cell growth. Conclusion These results showed that BD could induce cell apoptosis and suppress insulin signaling，potentially affecting nutrient digestion and absorption，ultimately inhibiting the growth and development of D. melanogaster.

The phenylpyrazole insecticide, fipronil, blocks insect RDL γ-aminobutyric acid (GABA) receptors, thereby impairs inhibitory neurotransmission. Some insect species, such as the diamondback moth ( Plutella xylostella ), possess more than one Rdl gene. The involvement of multiple Rdls in fipronil toxicity and resistance remain largely unknown. In this study, we investigated the roles of two Rdl genes, PxRdl1 and PxRdl2 , from P. xylostella in the action of fipronil. Expressed in Xenopus oocytes, Px RDL2 receptors were 40-times less sensitive to fipronil than Px RDL1. Px RDL2 receptors were also less sensitive to GABA compared to Px RDL1. Knockout of the fipronil-sensitive PxRdl1 gene reduced the potency of fipronil by 10 fold, whereas knockout of the fipronil-resistant PxRdl2 gene enhanced the potency of fipronil by 4.4 fold. Furthermore, in two fipronil-resistant diamondback moth field populations, the expression of PxRdl2 was elevated by 3.7-fold and 4.1-fold, respectively compared to a susceptible strain, whereas the expression of PxRdl1 was comparable among the resistant and susceptible strains. Collectively, our results indicate antagonistic effects of Px RDL1 and Px RDL2 on the fipronil action in vivo and suggest enhanced expression of fipronil-resistant PxRdl 2 potentially a new mechanism of fipronil resistance in insects.