摘要: While foraging,Vespula germanicausually return to abundant food sites. During this relocation behavior, these wasps learn to identify contextual cues associated with food position. We analyzed associative blocking in this species, that is, how an association with a conditioned stimulus (CS1) blocks subsequent learning when a novel stimulus (CS2) is added on a second foraging visit. Three groups of wasps (A, B, and C; total 74 individual wasps) were observed while collecting meat during one or two consecutive visits. In group A, an environmental cue (CS1) was paired with food placed at a specific site, and on the second visit, a second cue (CS2) was added while food remained in the same position. In a subsequent testing phase, CS1 was removed and the food source displaced nearby. We then recorded the number of hovers performed over the empty dish (previously baited). Group A wasps appeared to ignore the addition of CS2 on their second visit because they performed fewer hovers over the learned site. For group A, the duration of the decision-making process to finally fly toward the baited dish was shorter than when CS1 and CS2 were presented together on their first visit (group B). This is the first study to demonstrate the occurrence of associative blocking in vespids, confirming that a prior foraging experience influences subsequent food relocation inV. germanica. Our findings reveal that first learning episodes block further associations with novel contextual cues, contributing to understanding of complex cognitive processes involved inV. germanica ' sforaging behavior.

摘要: Fall armyworm (FAW),Spodoptera frugiperda(J.E. Smith), is a major polyphagous pest with the potential to seriously damage various crops. A better understanding of FAW's performance on different hosts may help to predict which plants will be attacked when the preferred host is absent, and facilitate the development of effective pest management practices. We compared the larval performance of FAW fed on maize with that of FAW fed on potato and tobacco, which are important crops in China, using an age-stage two-sex life table and adult female oviposition preference experiments. In cage experiments with potato, tobacco, or maize as the host, FAW reared on maize exhibited the strongest performance with shorter developmental time in the larval stage, longer longevity, and a higher reproductive rate in adults. Females oviposited on maize in preference to potato or tobacco. Compared with larvae fed on maize, those fed on potato and tobacco exhibited significantly lower survival, with only 31.61% and 8.13% developing to the adult stage, respectively. Several life table parameters, including the mean generation time (T), net reproductive rate (R-0), finite rate of increase (lambda), and intrinsic rate of natural increase (r) were negatively affected in FAW fed on potato and tobacco. Our results support the preference-performance hypothesis, that is, that herbivore females maximize fitness by choosing host plants associated with strong larval performance. Although larvae and adults performed poorly on potato and tobacco, their offspring will be capable of establishing populations on them, posing a potential threat to these crops in China.

摘要: Parental care directed to adult offspring is uncommon in animals. Such parental care has been documented in Xylocopinae bees (Hymenoptera: Apidae). Moreover, someCeratinabees (Xylocopinae) are known to feed mature siblings, and feeding of mature siblings is achieved by dwarf eldest daughters when mothers died. These daughters are intentionally malnourished by mothers and usually originate from the first brood cell. Here, we examined the pattern of care provided to young adults in three small European carpenter bees:Ceratina(Ceratina)cucurbitina,C. (Euceratina)chalybea, andC. (E.)nigrolabiata. Observations of nest departures and arrivals were performed to study foraging behavior. We detected intensive foraging behavior of mothers in all three studied species. However, we did not observe regular foraging behavior of daughters in any species. The experimental removal of mothers inC. cucurbitinaled to the emigration of young adults and did not initiate foraging activity in daughters. We conclude that the feeding of siblings does not occur in these species unlike in the American speciesC. calcarata. We detected female-biased sex ratios in the first brood cell inC. cucurbitinaandC. chalybea. Female offspring in the first brood cell was smaller than other female offspring only inC. cucurbitina. Our results show that a female-biased sex ratio and the small size of daughters in the first brood cell do not provide sufficient evidence for demonstrating the existence of an altruistic daughter and also that the pattern of maternal investment is not exclusively shaped by social interactions.

摘要: Workers ofApis cerana ceranaundergo an in-hive nursing to outdoor foraging transition, but the genes underlying this age-related transition remain largely unknown. Here, we sequenced the head transcriptomes of its 7-day-old normal nurses, 18- and 22-day-old normal foragers, 7-day-old precocious foragers and 22-day-old over-aged nurses to unravel the genes associated with this transition. Mapping of the sequence reads toApis melliferagenome showed that the three types of foragers had a greater percentage of reads from annotated exons and intergenic regions, whereas the two types of nurses had a greater percentage of reads from introns. Pair- and group-wise comparisons of the five transcriptomes revealed 59 uniquely expressed genes (18 in nurses and 41 in foragers) and 14 nurse- and 15 forager-upregulated genes. The uniquely expressed genes are usually low-abundance long noncoding RNAs, transcription factors, transcription coactivators, RNA-binding proteins, kinases or phosphatases that are involved in signaling and/or regulation, whereas the nurse- or forager-upregulated genes are often high-abundance downstream genes that directly perform the tasks of nurses or foragers. Taken together, these results suggest that the nurse-forager transition is coordinated by a social signal-triggered epigenetic shift from introns to exons/intergenic regions and the resulting transcriptional shift between the nurse- and forager-associated genes.

摘要: This study examines the rate of female answers to conspecific versus heterospecific male vibratory calls in three, closely related stonefly species:Zwicknia bifrons,Z. acuta, andZ. rupprechti. In a previous study those three species were recognized on the basis of their distinct male drumming calls along with differences in genital morphology and genetic divergence. During this study no-choice playback experiments using original male call samples from each species were performed, and the answer rate of females to conspecific and heterospecific signal variants was measured. Mixed effect logistic regression models were used to test if male call species identity had a statistically significant effect on female answer probability. Females answered conspecific male calls with significantly higher probability than heterospecific calls in all the three examined species, suggesting that the divergence of vibrational communication can be an important component of the prezygotic isolation between them. Low, but well detectable responsiveness to heterospecific calls was observable betweenZ. bifronsandZ. acuta, the two species closest to each other regarding mitochondrial genetic divergence and male call pattern similarity. Thus, our results are most congruent with a tight, gradual coevolution of male calls and female preferences.