Adverse environmental conditions can be evaded, tolerated or modified in order for an organism to survive. During their development, some insect larvae spin cocoons which, in addition to protecting their occupants against predators, modify microclimatic conditions, thus facilitating thermoregulation or reducing evaporative water loss. Silk cocoons are spun by honeybee (Apis mellifera) larvae and subsequently incorporated into the cell walls of the wax combs in which they develop. The accumulation of this hygroscopic silk in the thousands of cells used for brood rearing may significantly affect nest homeostasis by buffering humidity fluctuations. This study investigates the extent to which the comb may influence homeostasis by quantifying the hygroscopic capacity of the cocoons spun by honeybee larvae. When comb containing cocoons was placed at high humidity, it absorbed 11% of its own mass in water within 4 days. Newly drawn comb composed of hydrophobic wax and devoid of cocoons absorbed only 3% of its own mass. Therefore, the accumulation of cocoons in the comb may increase brood survivorship by maintaining a high and stable humidity in the cells.

Males of many insect species engage in ritualized behaviours during courtship that include the donation of a food gift to their partner. Although there is extensive diversity in nuptial gift form, a gift provided before mating typically serves to facilitate copulation, thereby increasing a male's mating success. Unlike other insects, the Hawaiian swordtail cricket Laupala shows protracted courtship that includes the serial donation of nuptial gifts prior to mating. Males transfer multiple spermless ‘micro’ spermatophores over several hours before the transfer of a single sperm containing a ‘macro’ spermatophore. By experimental manipulation of male courtship, we tested several hypotheses pertaining to the adaptive significance of protracted courtship involving nuptial gift donation in this system. We found that extensive courtship interactions improve insemination by causing the female reproductive tract to take in more sperm. This suggests that the enhancement of sperm transfer is due to the serial donation of microspermatophores, which would represent a relatively novel function for nuptial gifts provided before mating and highlights the importance of examining cryptic processes of sexual selection.

Terrestrial organisms need to limit evaporation from their bodies in order to maintain a homeostatic water balance. Owing to a large surface to volume ratio, arthropods are particularly susceptible to desiccation and have evolved behavioural and physiological mechanisms to conserve water. In social insects, water balance is also affected by the interactions between nestmates and by the architecture of the nest. For honeybees, humidity is particularly important for the brood because it affects the hatching success of eggs and because, unlike ants, honeybees cannot relocate their brood to parts of the nest with more favourable humidity. To advance the understanding of the water economy in honeybee nests, we investigated whether workers exhibit a hygropreference when exposed to a gradient of 24–90% relative humidity (RH) and whether the expression of this preference and their behaviour is affected by the presence of brood. The results show that young honeybee workers in the absence of brood exhibit a weak hygropreference for approximately 75% RH. When brood is present the expression of this preference is further weakened, suggesting that workers tend to the brood by distributing evenly in the gradient. In addition, fanning behaviour is shown to be triggered by an increase in humidity above the preferred level but not by a decrease. Our results suggest that humidity in honeybee colonies is actively controlled by workers.