Southern rice black-streaked dwarf virus, transmitted by the white-backed planthopper (Sogatella furcifera [Horváth]) (Hemiptera: Delphacidae) was first found in Guangdong Province, China. A previous study has demonstrated that the host plant preferences of S. furcifera are altered by infection with the virus, with virus-free S. furcifera preferring virus-infected rice plants over healthy rice plants, whereas viruliferous S. furcifera prefer uninfected plants. To test the hypothesis that odorant-binding proteins (OBPs) are involved in the preference of S. furcifera for virus-infected rice plants, we first compared the expression levels of SfurOBP2 and SfurOBP11 in virus-free and viruliferous S. furcifera. The results show that mRNA transcript of these 2 genes were significantly reduced in viruliferous S. furcifera. We then used RNAi-mediated gene silencing to confirm the function of these 2 odorant-binding proteins in host selection of S. furcifera. The results showed that silencing of the SfurOBP2 gene caused virus-free S. furcifera to no longer prefer virus-infected rice plants over uninfected rice plants, but the ability to locate host plants was maintained. These results indicate that SfurOBP2 appears to play a crucial role in the preference of S. furcifera for virus-infected rice plants.

A new pseudoguaianolide 1 and two new guaiane-type sesquiterpene glucosides 2 and 3, were isolated from the aerial parts of Ambrosia artemisiifolia L together with two known sesquiterpene dilactones 4 and 5. The new compounds were determined on the basis of spectroscopic and chemical methods to be 3β-acetoxy-4β-hydroxy-1α,7α, 10β,11αH-pseudoguaia-12,8β-olide (1), 1β,7β,9β,10β,13αH-guaia-4(5)-en-12,6β-olide 9-O-β-d-glucoside (2) and 4β-hydroxy-1α,5α,7α,9αH-guaia-10(14),11(13)-dien-12-acid 9-O-β-d-glucoside (3). The isolated compounds were evaluated for cytotoxicity against human promyelocytic leukemia HL-60 cell lines in vitro, but were all inactive.

Background: Cyproflanilide is a novel chemical that is already undergoing insecticide registration in China and has been categorized as a member of group 30 by the IRAC. Since it was first detected in 2019, the fall armyworm (FAW), Spodoptera frugiperda, has become a serious pest in China. Our laboratory and field efficacy trials indicated that cyproflanilide exhibits high larvicidal activity against FAW. However, the effect of cyproflanilide against FAW remains unknown. And it is worth exploring further before the cyproflanilide becomes commercially available. Results: We found larvae exposed to cyproflanilide had significantly shorter body length and higher death rates compared to control larvae. Additionally, we found surviving larvae had a significantly longer developmental period compared to control larvae. The potential molecular mechanisms of cyproflanilide against FAW were investigated using comparative transcriptomic analyses on larval samples subjected to three insecticide treatments, including cyproflanilide and two other commonly used insecticides against FAW in China, chlorantraniliprole and avermectin. We found that several subunits of the γ-aminobutyric acid receptor (GABAR), a possible target protein of cyproflanilide, were significantly up-regulated at the transcriptional level during cyproflanilide-induced stress. Additionally, between the control and cyproflanilide-treated samples, we identified 131 differentially expressed genes (DEGs) associated with detoxification metabolism. Of these, we found four P450 genes that were significantly up-regulated under cyproflanilide stress but were not DEGs when exposed to chlorantraniliprole and avermectin, or 23 other pesticides from previous reports. Furthermore, we discovered an interesting gene aggregation region for insect cuticle proteins (CPs) on the 18^th chromosome, which is likely related to FAW cross-resistance to cyproflanilide and avermectin. Conclusions: Our results contribute to a greater understanding of the mechanisms by which cyproflanilide affects FAW. Additionally, we identified the similarities and differences in transcriptomic profiling of FAW between the novel insecticide cyproflanilide and two other commonly used insecticides.

Chemosensory proteins are a family of insect-specific chemical sensors that sense specific chemical cues and regulate insect behavior. Chemosensory proteins have been identified and analyzed in many insect species, such as Drosophila melanogaster, Bactrocera dorsalis and Calliphora stygia. This research has revealed that these proteins play a crucial role in insect orientation, predation and oviposition. However, little is known about the chemosensory proteins of Chlorops oryzae, a major pest of rice crops throughout Asia. Comparative transcription analysis of the genes of Chlorops oryzae larvae, pupae and adults identified a total of 104 chemosensory genes, including 25 odorant receptors (ORs), 26 odorant-binding proteins (OBPs), 19 ionotropic receptors (IRs), 23 gustatory receptors (GRs) and 11 sensory neuron membrane proteins (SNMPs). The sequences of these candidate chemosensory genes were confirmed and used to construct phylogenetic trees. Quantitative real-time PCR (qRT-PCR) confirmed that the expression of candidate OR genes in different developmental stages was consistent with the fragments per kilobase per million fragments (FPKM) values of differentially expressed genes (DEGs). The identification of chemosensory genes in C. oryzae provides a foundation for the investigation of the function of chemosensory proteins in this species, which, in turn, could allow the development of new, improved methods of controlling this pest.

Two new clerodane-type diterpenes, tinosporins C (1) and tinosporins D (2) were isolated from the stems of Tinospora sagittata (Oliv.), together with three known ones, columbin (3), tinophylloloside (4), and tinospinoside D (5). The structures of these compounds were determined on the basis of spectroscopic data interpretation, with that of the absolute configuration of compound 1 was assigned by experimental and calculated ECD spectra. The cytotoxicity and α-glucosidase inhibitory activities of isolated compounds were evaluated in vitro.