Jinge Yuan

Neoseiulus barkeri Hughes, a widely used biological control agent for small pests, relies on its sophisticated olfactory system for key behaviors such as foraging, prey location, and mating. While herbivore‐induced plant volatiles (HIPV) are well‐studied in other insects and large natural enemies, the olfactory mechanisms of phytoseiid mites like N. barkeri remain largely uncharacterized, hindering advances in biological control. This study investigated the potential function of foreleg tarsal sensory organs of the phytoseiid mites in HIPV recognition. The results showed N. barkeri females and males were both attracted to the full blend and six individual volatile originated from cowpea leaves infested by Tetranychus urticae Koch. N. barkeri females no longer showed odor preferences once tarsi of leg I were excised, but attraction was not affected when tarsi of leg IV were excised. SEM analysis characterized the setae types in the distal part of tarsi in leg I as stout peg‐shaped structures without sockets, identified as olfactory sensilla. Excising tarsi of legs did not affect predation or copulation in N. barkeri , but reduced its walking speed and mate‐searching efficiency. Expression of three Niemann–Pick type C2 genes in excised tarsi of leg I was significantly down regulated when induced by ocimene. These results suggest that tarsi of forelegs of phytoseiids are involved in the perception of HIPV, as well as in discrimination of odor signals. Our study provides a foundation for further elucidation of effective control strategies against small insect and mite pests with predators and HIPV‐based components as attractants or repellents.

Coccinella transversoguttata is a crucial beneficial insect within Coccinellidae, playing a significant role in biological pest control and maintaining ecological balance. Given its adaptability to agricultural ecosystems and natural regulation of pest populations, C. transversoguttata could serve as a valuable model for genetic research in the family Coccinellidae and contribute to the development of sustainable pest management strategies. Here, we report a chromosome-level genome assembly of C. transversoguttata with a genome size of 453.64 Mb and a contig N50 length of 22.99 Mb. The genome contained 16,464 protein-coding genes, of which 14,286 genes (86.77%) were functionally annotated. Additionally, we identified 309.93 Mb (68.32%) of the assembled sequences are repetitive sequences. Our study provides a reliable genome resource, and lays a solid foundation for understanding the evolution, adaptation, and genetic improvement of ladybird beetles within Coccinellidae.

The stink bug, Eocanthecona furcellata Wolff (Hemiptera: Pentatomidae) shows significant promise as a biological control agent against lepidopteran pests in tropical and subtropical areas. However, securing suitable food remains a persistent issue for the mass rearing of this beneficial insect. To understand how different feeding strategies impact reproductive success, we evaluated their effects on critical life table parameters and ovary development using a range of feeding options: natural prey Spodoptera litura Fabricius (Lepidoptera: Noctuidae) and Spodoptera exigua Hubner, alternative prey Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae), and an advanced artificial diet. E. furcellata fed on S. litura had the highest fecundity (326.96 eggs) and net reproduction rate (86.04 offspring). Moreover, those fed T. molitor exhibited the highest survival rate during the nymph stage (61.86%). Among all tested treatments, ovarian tube length reached its peak on the 14th day following the emergence of the adult. The group fed S. litura had the longest average length (4.021 mm), followed by those fed S. exigua (3.986 mm) and T. molitor (3.904 mm). Notably, E. furcellata fed on S. exigua displayed the highest number of fully developed follicles between days 3 and 21 after emergence. This research underscores the efficacy of utilizing natural prey, especially S. litura, and alternative prey, T. molitor, for enhancing the reproductive success and survival of E. furcellata, providing critical insights for optimizing mass-rearing techniques and informing integrated pest management strategies that leverage this beneficial insect for effective biological control across diverse agricultural systems.

In arthropods, a host of studies focused on insect olfactory systems, where most functional proteins including odorant-binding proteins (OBPs) and chemosensory proteins (CSPs) have been identified. However, in other arthropods such as ticks and mites, genes encoding for OBPs and CSPs are absent. The Niemann-Pick type C2 (NPC2), as a third class of binding proteins, was indicated as potential carriers for semiochemicals and participants in chemical communication. Here, we cloned three full-length NPC2 genes (NbNPC2-1, NbNPC2-2 and NbNPC2-3) from a predatory mite Neoseiulus barkeri Hughes (Acari: Phytoseiidae) and investigated the expression levels of these genes by quantitative real-time PCR. These NPC2 proteins possessed a conserved motif of six cysteines paired in three disulfide bridges with a coincidence to insect OBPs. The 3D molecular modeling of NbNPC2 showed ligand-binding pocket of NbNPC2-1 was composed of a flexible β-structure that contributed to binding to a wide range of potential semiochemicals. Three NPC2 genes all possessed one signal peptide revealed their specific character as secretory proteins. Three NPC2 genes in N. barkeri displayed the highest expression levels in adult males, suggesting a putative role in detecting of the female sex pheromones and highly specific binding to female sex pheromone. The expression levels were lowest in the stage of eggs and increased with developmental stage growing, indicating that NPC2 genes were continuously expressed in post-embryonic stages. NbNPC2-1 in the stage of adult females was expressed 6 and 4 times higher than that of larva and nymph, suggesting NbNPC2-1 might contribute an important role in odor recognition of adult females to hunt for suitable areas for the oviposition and predation. These results showed that NPC2 genes might be involved in chemical communications of adult males, and that NbNPC2-1 preformed specified olfactory functions in adult females. This study provided a foundation for research to determine the roles of NPC2 proteins acting as odorant carrier and involved in chemical communication in phytoseiid mites.