Functional Asymmetries Routing the Mating Behavior of the Rusty Grain Beetle, Cryptolestes ferrugineus (Stephens) (Coleoptera: Laemophloeidae)

Lateralized courtship behavior in Ostrinia furnacalis (Lepidoptera: Crambidae): influence of gender, sexual experience, and its effects on mating success

Lateralization in mating behavior is increasingly recognized as a significant trait in insect species, yet its influence associated with gender, and sexual experience in Ostrinia furnacalis (Guenée) remains poorly understood. This study examines how lateralized mating behaviors, gender, and sexual experience interact to influence mating success and efficiency in O. furnacalis. We conducted controlled mating trials to assess how gender and sexual experience shape lateralized directional approaches (eg right- or left-biased) and turnings (eg 180° right- or left-biased) across the pre-copulatory, copulatory, and post-copulatory phases. Our results indicated that, in terms of gender, males were more likely to approach females, whereas females rarely initiated approaches, with both approaches each other simultaneously being infrequent. Both virgin and experienced males showed higher right-biased directional approaches than the front approaches to the females with more left-biased directional turns for successful intromissive copulation. Experienced males showed greater mating success than virgins. In contrast, experienced females exhibited lower mating success and longer post-copulatory interactions compared to virgin females, particularly duration of copulation. Post-copulatory interactions showed that antennal touching occurred more frequently in the experienced pairs. This study is the first to demonstrate the combined influence of gender and sexual experience on lateralized mating dynamics, with male courtship behaviors linked to learning processes. The results indicate that sexual experience, potentially involving learning and memory processes, significantly enhances mating efficiency and fitness in O. furnacalis. This research provides a more nuanced understanding of lateralized mating behaviors in O. furnacalis, with implications for refining pest management strategies in agricultural environments.

Contrasting Responses to Ethenylbenzene (Styrene) and 2-Ethyl-1-hexanol Suggest their Role as Chemical Cues in Host Selection by the Seed Beetle Zabrotes subfasciatus (Coleoptera: Chrysomelidae: Bruchinae)

Seed beetles spend most of their lives within the seeds of host plants belonging to the Fabaceae family. Evidence suggests the cues that mediate pre-oviposition behaviour in Zabrotes subfasciatus (Boheman) are volatile organic compounds (VOCs) emitted by the seeds and suggests differential abilities in environment sensing between sexes. Here, we tested whether VOCs from different legume species trigger different levels of attraction, whether females and males differ in their ability to respond to VOCs, and whether the seeds promoting different behaviours feature singular VOCs. Finally, we tested females' response to selected VOCs from legume seeds with different levels of attraction. Behavioural assays testing the beetles' response to four Fabaceae species allowing varied levels of fitness (Phaseolus vulgaris, Glycine max, Lens culinaris, and Cicer arietinum) and antenna removal assays confirmed volatiles emitted by the seeds act as chemical cues for females and showed the seeds of the tested legume species trigger different levels of attraction. GC-MS analysis revealed the seeds of two of the species at the extreme of the preference hierarchy feature singular VOCs profiles and abundance. One of the differentially expressed VOCs found in higher quantities in P. vulgaris (ethenylbenzene = styrene) and one in C. arietinum (2-ethyl-1-hexanol) mediate opposing behaviours in Z. subfasciatus females. These results suggest host choice in Z. subfasciatus relies upon at least a two-component kairomone-based system: styrene attracts females to P. vulgaris seeds and 2-ethyl-1-hexanol keeps them from choosing C. arietinum as a substrate for oviposition. The system has evolutionary and agricultural relevance because it may allow for "niche" specialisation in seed stores and natural environments and may help develop pest management strategies.

Sublethal Effects of α-Cypermethrin on the Behavioral Asymmetries and Mating Success of Alphitobius diaperinus

Sublethal exposure to insecticides can adversely impact various biological and behavioral characteristics of insects. Although α-cypermethrin has been previously tested for its effects on control of Alphitobius diaperinus, there is no knowledge about the effect of this insecticide on its behavioral asymmetries and mating success. Μales at all exposures (control, LC10, and LC30), that first approached their mate, showed right-biased tendency (approached their mate from their right side) in mate recognition. Females, however, showed variation in this behavior between the three exposures. Right-biased tendency of males in all treatment scenarios led to a higher percentage of successful copulations compared to the three other directions. For males that first approached their mate, the insecticide did not affect their lateralization of the first approach but did affect their copulation success. The duration of copulation time was reduced after the exposure to the insecticide, with the longest duration noted in the control females (63.0 s) and the lowest in the α-cypermethrin LC30 females (46.9 s). Moreover, at the α-cypermethrin LC10 exposure, mate recognition time was reduced, as opposed to α-cypermethrin LC30 exposure where mate recognition time was increased. These results can be further utilized to uncover the behavioral impacts of insecticides, enhancing the effectiveness of pest management in warehouses and poultry production facilities.

Lateralised courtship behaviour and its impact on mating success in Ostrinia furnacalis (Lepidoptera: Crambidae)

Lateralisation is a well-established phenomenon observed in an increasing number of insect species. This study aims to obtain basic details on lateralisation in courtship and mating behaviour in Ostrinia furnacalis, the Asian corn borer. We conducted laboratory investigations to observe lateralisation in courtship and mating behaviours in adult O. furnacalis. Our goal was also to detect lateralised mating behaviour variations during sexual interactions and to elucidate how these variances might influence the mating success of males. Our findings reveal two distinct lateralised traits: male approaches from the right or left side of the female and the direction of male turning displays. Specifically, males approaching females from their right side predominantly exhibited left-biased 180° turning displays, while males approaching females from the left-side primarily displayed right-biased 180° turning displays. Notably, left-biased males, executing a 180° turn for end-to-end genital contact, initiated copulation with fewer attempts and began copulation earlier than their right-biased approaches with left-biased 180° turning displays. Furthermore, mating success was higher when males subsequently approached the right side of females during sexual encounters. Left-biased 180° turning males exhibited a higher number of successful mating interactions. These observations provide the first report on lateralisation in the reproductive behaviour of O. furnacalis under controlled laboratory conditions and hold promise for establishing reliable benchmarks for assessing and monitoring the quality of mass-produced individuals in pest control efforts.

Lateralized Movements during the Mating Behavior, Which Are Associated with Sex and Sexual Experience, Increase the Mating Success in Alphitobius diaperinus (Coleoptera: Tenebrionidae)

In the present study, we explored the effects of displacement directionality in mating behavior (i.e., lateralized and non-lateralized movements) on mating success (i.e., copulation occurs) and efficiency (i.e., time length at which copulation is achieved), and its association with sex and sexual experience in A. diaperinus. To do so, we carried out mating experiments and recorded the behavior of the mating pair during the whole mating sequence (i.e., precopulatory and copulatory phases). During the precopulatory phase, independently of sex and sexual experience, all beetles performed non-lateralized (i.e., backside or frontside) approaches; however, only sexually experienced beetles showed lateralized approaches (i.e., right-side and left-side). Notably, experienced males exhibited greater mating success than virgin males. After the approach, both virgin and experienced males displayed lateralized and non-lateralized mounts on the females with distinct mating success. Regardless of their sexual experience, 100% of successful mating attempts were achieved when males mounted from the females' right side. Furthermore, the development of lateralized approaches and mounts reduces the time of mating sequence span compared with non-lateralized behaviors. We highlight the importance of lateralization in mating behavior and sexual experience to achieve higher mating success, addressing a potential learning ability of beetles based on experience.

Biology, Ecology, and Behavior of Rusty Grain Beetle (Cryptolestes ferrugineus (Stephens))

Cryptolestes ferrugineus, the rusty grain beetle, is a cosmopolitan pest that has adapted to cool and warm climates due to its unique biology, ecology, and behavior. The rusty grain beetle is a pest of high economic importance; hence, understanding their biology, ecology, and behavior could be useful in designing effective management strategies. An extensive literature survey was conducted using the databases Web of Science and Scopus. Information on country-wise publications from 1949 to 2023 on C. ferrugineus was provided, and a table illustrating the distribution of C. ferrugineus was also presented to demonstrate the global significance of C. ferrugineus. We overviewed their life stages, morphology, and factors influencing their biology, ecology, and behavior, such as refuge-seeking behavior, flight activity, mating behavior, interspecific interaction with other species, movement, and distribution. Mathematical models focusing on C. ferrugineus population dynamics and movement were also presented. In order to advance our knowledge on C. ferrugineus, the following possible avenues for future research were outlined: application of molecular markers and population genetic approaches to understand their evolutionary history; mechanisms responsible for adaptation and resistance to insecticide; interspecific interaction in storage facilities and wider landscapes; and identification of microbial roles in the ecology, behavior, and control of C. ferrugineus.