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The regulation of locomotor behavior is essential for insects to perform their life activities. The central nervous system plays a pivotal role in modulating physiological behaviors, particularly movement, with neuropeptides serving as key modulators of these processes. Among these, adipokinetic hormone (AKH) was originally identified in insects as a neurohormone involved in lipid mobilization. This study investigates the functional role of AKHs (AKH1 and AKH2) and their receptor (AKHR) in regulating locomotion in the red flour beetle, Tribolium castaneum. Using functional calcium reporter assays, we demonstrated that AKHR is activated by two mature AKH peptides from T. castaneum, with half-maximal effective concentrations (EC50) falling within the nanomolar range. Gene expression analysis confirmed the presence of AKH1 and AKH2 transcripts in the brain, while AKHR expression was localized to the fat body and carcass. The silencing of AKHs or AKHR through RNA interference resulted in a significant reduction in both movement distance and duration. Collectively, these findings highlight the regulatory influence of AKH/AKHR signaling in locomotor activity in T. castaneum, thereby advancing our understanding of the molecular mechanisms underlying locomotor control in this economically important insect species.

Natalisin (NTL) is a conserved neuropeptide, only present in insects, that has been reported to regulate their sexual activity. In this study, we investigated the involvement of NTL in the reproductive behaviors of a major invasive pest, Spodoptera frugiperda . We identified NTL precursor-encoded transcripts, and evaluated their transcript levels in different stages and tissues of S. frugiperda . The results showed that the NTL transcript level was expressed in both male and female pupae and both male and female adults in the later stage. It was highly expressed in male pupae, 3-day-old male and female adults, and 5-day-old male adults. In different tissues, the expression level is higher in the male and female adult brain and male testis. Immunohistochemical staining of the brain of S. frugiperda female and male adults revealed that three pairs of brain neurons of S. frugiperda adults of both sexes secreted and expressed NTL. To study the role of NTL in reproductive behaviors, NTL was silenced in S. frugiperda male and female adults by RNA interference (RNAi) technology, the results showed that silencing NTL could significantly affect the sexual activity behavior of the adults, reducing the calling rate of females, the courtship rate of males, and the mating rate. In summary, this study emphasizes the important role of NTL in regulating the mating behavior and sexual activity of S. frugiperda in both male and female adults, potentially laying a foundation to employ NTL as a new insect-specific target to control populations of pest insects.

Bactrocera dorsalis is a major pest causing economic losses in fruit and vegetable production. Current control methods, such as synthetic pesticides and male annihilation techniques, have drawbacks, including health risks, resistance development, and ineffectiveness against females. This study investigates the attractions and oviposition stimulant activities of five common volatiles—[isobutyl acetate (A), isoamyl acetate (B), isobutyl butyrate (C), isoamyl isovalerate (D), and isoamyl butyrate (E)]—from the most preferred hosts: mango, guava, orange, and banana. These volatiles were tested at three different concentrations, both individually and in complex blends. Choice tests were performed using a Y-tube olfactometer and Petri plate with agarose assays, and antennal responses were determined using electroantennogram (EAG) recordings. Among them, a blend comprising 1.25% isoamyl acerate (10.95 µg/µl), 1.25% isoamyl isovalerate (10.75 µg/µl), and 20% isoamyl butyrate (172.40 µg/µl) (B1D1E3) emerged as the most potent attractant for both sexes and oviposition stimulant for females. Moreover, combining B1D1E3 with mango, banana, or orange juice significantly enhanced egg-laying behavior. Electrophysiological recordings supported these findings, with B1D1E3 eliciting the strongest antennal responses. Results suggest B1D1E3 could be used to elicit strong oviposition responses in mass rearing of B. dorsalis for the Sterile Insect Technique.

Background Plant resistance inducers based on nanomaterials (NMs) are a cutting-edge and promising field of interdisciplinary research, focused on developing environmentally and ecologically friendly alternatives for protecting crops. Studies have shown that NMs composed of silicon (SiO 2 ) and carbon quantum dots (CDs) can help plants better withstand various environmental and pest-related stresses. Results We synthesized and characterized SiO 2 -coated CDs (SiO 2 @CDs) NMs that were found to be absorbed by tobacco leaves. Our research demonstrated that spraying tobacco leaves with a solution containing 100 mg/L SiO 2 @CDs was more effective in promoting plant growth and controlling pest populations, specifically adult aphids compared to using either CDs or SiO 2 alone at the same concentration. The group treated with SiO 2 @CDs achieved a significant 71% mortality of adult aphids after just 7 days, which was significantly different from the control group. Mechanistically, SiO 2 @CDs enhanced both the plant’s physical resistance by utilizing Si, and stimulated the production of chemical defense compounds (such as salicylic acid), thereby improving aphid resistance. Additionally, the application of SiO 2 @CDs significantly reduced oxidative stress in the leaves caused by aphid infestation, bolstered the activity of antioxidant enzymes like superoxide dismutase and peroxidase, and reduced malondialdehyde accumulation. Our biosafety experiments indicated that the SiO 2 @CDs were less toxic and safer for non-target organisms in the environment, as well as for human cells. Conclusion This study demonstrates that SiO 2 @CDs exhibit excellent performance as a multifunctional insecticide in managing aphid-induced plant pest infestations, highlighting their promising and environmentally friendly potential in pest control and agroecosystem optimization.

Natalisins (NTLs) are conservative neuropeptides, which are only found in arthropods and are documented to regulate reproductive behaviors in insects. In our previous study, we have confirmed that NTLs regulate the reproductive process in an important agricultural pest, Bactrocera dorsalis (Hendel). Hence, in this study, to further confirm the in vivo function of NTL receptor (NTLR) and assess the potential of NTLR as an insecticide target, RNA interference targeting NTLR mRNA was performed. We found that mating frequencies of both males and females were reduced by RNAi-mediated knockdown of the NTLR transcript, while there was no effect on mating duration. Moreover, we functionally expressed the B. dorsalis NTLR in Chinese Hamster Ovary (CHO) cells and was co-transfected with an aequorin reporter to measure ligand activities. A total of 13 biostable multi-Aib analogs were tested for agonistic and antagonistic activities. While most of these NTL analogs did not show strong activity, one analog (NLFQV[Aib]DPFF[Aib]TRamide) had moderate antagonistic activity. Taken together, we provided evidence for the important roles of NTLR in regulating mating frequencies of both male and female in this fly and also provided in vitro data on mimetic analogs that serve as leading structures for the development of agonists and antagonists to disrupt the NTL signaling pathway.

The biogenic amine octopamine plays a critical role in the regulation of many physiological processes in insects. Octopamine transmits its action through a set of specific G-protein coupled receptors (GPCRs), namely octopamine receptors. Here, we report on a β-adrenergic-like octopamine receptor gene (BdOctβR1) from the oriental fruit fly, Bactrocera dorsalis (Hendel), a destructive agricultural pest that occurs in North America and the Asia-Pacific region. As indicated by RT-qPCR, BdOctβR1 was highly expressed in the central nervous system (CNS) and Malpighian tubules (MT) in the adult flies, suggesting it may undertake important roles in neural signaling in the CNS as well as physiological functions in the MT of this fly. Furthermore, its ligand specificities were tested in a heterologous expression system where BdOctβR1 was expressed in HEK-293 cells. Based on cyclic AMP response assays, we found that BdOctβR1 could be activated by octopamine in a concentration-dependent manner, confirming that this receptor was functional, while tyramine and dopamine had much less potency than octopamine. Naphazoline possessed the highest agonistic activity among the tested agonists. In antagonistic assays, mianserin had the strongest activity and was followed by phentolamine and chlorpromazine. Furthermore, when the flies were kept under starvation, there was a corresponding increase in the transcript level of BdOctβR1, while high or low temperature stress could not induce significant expression changes. The above results suggest that BdOctβR1 may be involved in the regulation of feeding processes in Bactrocera dorsalis and may provide new potential insecticide leads targeting octopamine receptors.

A new Allacta xizangensis sp. nov. (Blattodea: Ectobiidae: Pseudophyllodromiinae) is described and assigned to the polygrapha species group. Four known species, A. robusta,A. bimaculata, A. transversa, A. ornata, are re-described and illustrated based on type material and specimens kept in the collection of Southwest University (SWU), Sun Yat-Sen University (SYSU), Hebei University (HBU), China and Institute of Zoology, Chinese Academy of Sciences (IZCAS) and the Russian Academy of Sciences (ZIN). The hitherto unknown male of A. transversa is described with a special display of its genitalia. A key is given to identify the males of Allacta from China. The tarsomere ultrastructure of all the legs of A. ornata was examined by scanning electron microscopy.

Natalisins (NTLs) are conservative neuropeptides, which are only found in arthropods and are documented to regulate reproductive behaviors in insects. In our previous study, we have confirmed that NTLs regulate the reproductive process in an important agricultural pest, Bactrocera dorsalis (Hendel). Hence, in this study, to further confirm the in vivo function of NTL receptor (NTLR) and assess the potential of NTLR as an insecticide target, RNA interference targeting NTLR mRNA was performed. We found that mating frequencies of both males and females were reduced by RNAi-mediated knockdown of the NTLR transcript, while there was no effect on mating duration. Moreover, we functionally expressed the B. dorsalis NTLR in Chinese Hamster Ovary (CHO) cells and was co-transfected with an aequorin reporter to measure ligand activities. A total of 13 biostable multi-Aib analogs were tested for agonistic and antagonistic activities. While most of these NTL analogs did not show strong activity, one analog (NLFQV[Aib]DPFF[Aib]TRamide) had moderate antagonistic activity. Taken together, we provided evidence for the important roles of NTLR in regulating mating frequencies of both male and female in this fly and also provided in vitro data on mimetic analogs that serve as leading structures for the development of agonists and antagonists to disrupt the NTL signaling pathway.

The biogenic amine octopamine plays a critical role in the regulation of many physiological processes in insects. Octopamine transmits its action through a set of specific G-protein coupled receptors (GPCRs), namely octopamine receptors. Here, we report on a [beta]-adrenergic-like octopamine receptor gene (BdOct[beta]R1) from the oriental fruit fly, Bactrocera dorsalis (Hendel), a destructive agricultural pest that occurs in North America and the Asia-Pacific region. As indicated by RT-qPCR, BdOct[beta]R1 was highly expressed in the central nervous system (CNS) and Malpighian tubules (MT) in the adult flies, suggesting it may undertake important roles in neural signaling in the CNS as well as physiological functions in the MT of this fly. Furthermore, its ligand specificities were tested in a heterologous expression system where BdOct[beta]R1 was expressed in HEK-293 cells. Based on cyclic AMP response assays, we found that BdOct[beta]R1 could be activated by octopamine in a concentration-dependent manner, confirming that this receptor was functional, while tyramine and dopamine had much less potency than octopamine. Naphazoline possessed the highest agonistic activity among the tested agonists. In antagonistic assays, mianserin had the strongest activity and was followed by phentolamine and chlorpromazine. Furthermore, when the flies were kept under starvation, there was a corresponding increase in the transcript level of BdOct[beta]R1, while high or low temperature stress could not induce significant expression changes. The above results suggest that BdOct[beta]R1 may be involved in the regulation of feeding processes in Bactrocera dorsalis and may provide new potential insecticide leads targeting octopamine receptors.

A new Allacta xizangensissp. nov. (Blattodea: Ectobiidae: Pseudophyllodromiinae) is described and assigned to the polygrapha species group. Four known species, A. robusta,A. bimaculata, A. transversa, A. ornata, are re-described and illustrated based on type material and specimens kept in the collection of Southwest University (SWU), Sun Yat-Sen University (SYSU), Hebei University (HBU), China and Institute of Zoology, Chinese Academy of Sciences (IZCAS) and the Russian Academy of Sciences (ZIN). The hitherto unknown male of A. transversa is described with a special display of its genitalia. A key is given to identify the males of Allacta from China. The tarsomere ultrastructure of all the legs of A. ornata was examined by scanning electron microscopy.