摘要: The behavioral strategies and mechanisms by which some insects maintain monogamous mating systems are not well understood. We investigated the mating system of the bark beetle Dendroctonus valens, and identified several contributing mechanisms. Field and laboratory observations suggest the adults commonly form permanent bonds during host colonization. Moreover, it showed mated females that remained paired with males produced more offspring than mated females that were alone in galleries. In bioassays, a second female commonly entered a gallery constructed by a prior female. Videos show she commonly reached the location of the first female, but they did not engage in actual fighting. Rather, the second female typically departs to form her own gallery. Acoustic signaling likewise does not appear to influence female-female encounters, based on controlled muting experiments. Instead, the intruder appears to perceive the resident's presence by physical contact. Both acoustic signals and volatiles released by females during gallery constructing were shown to attract males. After a male joined a female in a gallery, the male-produced aggressive sounds, which were shown by playback to deter other males from entering the gallery. Unlike female-female interactions, resident males use their head and rear to push intruders out of galleries. Additionally, volatiles released by males during feeding repelled intruding males, discouraging them from entering the gallery. Males also construct plugs that block the entrance, which may prevent subsequent males and predators from entering the gallery. Thus, D. valens has evolved multifaceted mechanisms contributing to single pairings that confer benefits to both sexes.

摘要: Animals use diverse sensory stimuli to navigate their environment and to recognize rewarding food sources. Honey bees use visual attributes of the targeted food source, such as its color, shape, size, direction and distance from the hive, and the landmarks around it to navigate during foraging. They transmit the location information of the food source to other bees if it is highly rewarding. To investigate the relative importance of these attributes, we trained bees to feeders in two different experiments. In the first experiment, we asked whether bees prefer to land on (a) a similar feeder at a different distance on the same heading or on (b) a visually distinct feeder located at the exact same location. We found that, within a short foraging range, bees relied heavily on the color and the shape of the food source and to a lesser extent on its distance from the hive. In the second experiment, we asked if moving the main landmark or the feeder (visual target) influenced recruitment dancing for the feeder. We found that foragers took longer to land and danced fewer circuits when the location of the food source, or a major landmark associated with it, changed. These results demonstrate that prominent visual attributes of food sources and landmarks are evidently more reliable than distance information and that foraging bees heavily utilize these visual cues at the later stages of their journey.

摘要: Continuous jumping behavior, a kind of endurance locomotion, plays important roles in insect ecological adaption and survival. However, the methods used for the efficient evaluation of insect jumping behavior remain largely lacking. Here, we developed a locomotion detection system named JumpDetector with automatic trajectory tracking and data analysis to evaluate the jumping of insects. This automated system exhibits more accurate, efficient, and adjustable performance than manual methods. By using this automatic system, we characterized a gradually declining pattern of continuous jumping behavior in 4th-instar nymphs of the migratory locust. We found that locusts in their gregarious phase outperformed locusts in their solitary phase in the endurance jumping locomotion. Therefore, the JumpDetector could be widely used in jumping behavior and endurance locomotion measurement.

摘要: Our current understanding of how species have evolved is mainly based on comparative phylogenetic methods, which use phylogenies to infer the evolution of traits. The development of ancestral state reconstruction (ASR) methods has provided the tools to reconstruct trait evolution, which are widely used in fields like evolutionary biology, macroecology and paleontology. As there are different elements involved in those analyses, with different levels of uncertainty (i.e. relating to branch length estimation, trait coding, statistical framework, taxon sampling or software), the various combinations of these elements likely have a strong impact on the reconstruction of the evolution of traits, potentially leading to opposite conclusions. To assess the impact of these different elements in ASR, we performed a set of analyses, including all possible combinations of such elements and using the evolution of migratory behavior in Sylvia warblers as a case study, which was coded as a continuous or as a discrete character. Our results show that taxon sampling, character coding, tree shape, statistical framework and software all significantly affect ASR, both individually and in combination. Not all reconstructed tree nodes show discrepancies, but in the critical ones most pairwise comparisons between analyses lead to conflicting and unexpectedly antagonistic results (zero migration vs fully migratory), thus challenging interpretations of trait evolution. We propose some possible solutions to partly inform decisions, involving the method selection and the incorporation of biological or fossil evidence regarding how traits evolve, but our results demand serious rethinking about how the research community currently uses ASR.

摘要: The mechanism underlying detection of seed dormancy by scatter-hoarding rodents is unclear, although previous work suggests that the pericarp plays an important role in signaling dormancy status. Eastern gray squirrels (Sciurus carolinensis) consume early germinating seeds as they are more likely to perish immediately, whereas dormant seeds tend to be cached. To examine the mechanisms underlying dormancy detection, we characterized physical and chemical differences between germinating and dormant pericarps of northern red oak (Quercus rubra), American chestnut (Castanea dentata) and the BC3 hybrid of Chinese chestnut and American chestnut (Castanea mollissima x C. dentata) using scanning electron microscopy and gas chromatography- mass spectrometry. We found that, as seeds break dormancy, the wax layer on the pericarp degrades and is accompanied by the escape of lower molecular weight kernel compounds or lipid metabolism byproducts. Our field experiments showed that squirrels were 4-8 times more likely to consume seeds that were altered to remove pericarp wax coating or that were sprayed with seed chemicals. We argue that dormancy detection by scatter-hoarding rodents is a complex process involving physical cues such as loss of pericarp wax and chemical cues such as emission of olfactory cues.