A recent study on ladybird, Menochilus sexmaculatus (Fabricius) demonstrates that males perform post-copulatory mate guarding in the form of prolonged mating durations. We investigated whether food resource fluctuation affects pre- and post-copulatory behaviour of M. sexmaculatus. It has not been studied before in ladybirds. For this, adults were subjected to prey resource fluctuations sequentially at three levels: post-emergence (Poe; 10 days), pre-mating (Prm; 24 h) and post-mating (Pom; 5 days; only female). The food resource conditions at each level could be any one of scarce, optimal or abundant. Pre-copulatory and post-copulatory behaviour, and reproductive output were assessed. Post-emergence and pre-mating nutrient conditions significantly influenced the pre-copulatory behaviour. Males reared on scarce post-emergence conditions were found to require significantly higher number of mating attempts to establish mating unlike males in the other two food conditions. Under scarce post-emergence and pre-mating conditions, time to commencement of mating and latent period were high but opposite result was obtained for mate-guarding duration. Fecundity and per cent egg viability were more influenced by post-mating conditions, with scarce conditions stopping oviposition regardless of pre-mating and post-emergence conditions. Present results indicate that pre- and post-copulatory behaviour of ladybird is plastic in nature in response to food resource fluctuations.

Although sex biases in natal dispersal are well known among birds and mammals, female-biased dispersal in polygynous mammals is rare. North American porcupines are polygynous and recent evidence suggests that natal dispersal in this species may be female-biased. We used data on disappearances, immigration, and reproductive behaviours to characterize natal dispersal and examine the extent to which inbreeding avoidance may motivate natal dispersal in porcupines. We predicted that, if female porcupines were the predominant dispersers, rates of disappearance and immigration would be higher for females than for males. Also, if females disperse to avoid mating with fathers, then the mean age of females at first conception should be less than the mean residence time of adult males. Population data suggested that natal dispersal was female-biased because a higher proportion of females (31%) disappeared than males (11%), and 78% of 18 immigrants observed in the population were females. Data on pregnancies indicated that female age at first conception ([ape ]25 months) was less than the mean residence time of adult males ([ape ]26 months), suggesting that female porcupines may disperse to avoid incestuous matings with fathers. Little is known regarding potential resource competition between mothers and offspring, or on how philopatric males avoid mating with their mothers. Additional data are needed in these areas to interpret dispersal tendencies in porcupines.