Weather Forecasting by Insects: Modified Sexual Behaviour in Response to Atmospheric Pressure Changes

Abstract

Prevailing abiotic conditions may positively or negatively impact insects at both the individual and population levels. For example while moderate rainfall and wind velocity may provide conditions that favour development, as well as movement within and between habitats, high winds and heavy rains can significantly decrease life expectancy. There is some evidence that insects adjust their behaviours associated with flight, mating and foraging in response to changes in barometric pressure. We studied changes in different mating behaviours of three taxonomically unrelated insects, the curcurbit beetle, Diabrotica speciosa (Coleoptera), the true armyworm moth, Pseudaletia unipuncta (Lepidoptera) and the potato aphid, Macrosiphum euphorbiae (Hemiptera), when subjected to natural or experimentally manipulated changes in atmospheric pressure. In response to decreasing barometric pressure, male beetles exhibited decreased locomotory activity in a Y-tube olfactometer with female pheromone extracts. However, when placed in close proximity to females, they exhibited reduced courtship sequences and the precopulatory period. Under the same situations, females of the true armyworm and the potato aphid exhibited significantly reduced calling behaviour. Neither the movement of male beetles nor the calling of armyworm females differed between stable and increasing atmospheric pressure conditions. However, in the case of the armyworm there was a significant decrease in the incidence of mating under rising atmospheric conditions, suggesting an effect on male behaviour. When atmospheric pressure rose, very few M. euphorbiae oviparae called. This was similar to the situation observed under decreasing conditions, and consequently very little mating was observed in this species except under stable conditions. All species exhibited behavioural modifications, but there were interspecific differences related to size-related flight ability and the diel periodicity of mating activity. We postulate that the observed behavioral modifications, especially under decreasing barometric pressure would reduce the probability of injury or death under adverse weather conditions.

The Mothematics of Female Pheromone Signaling: Strategies for Aging Virgins

“…It is also unclear as to the relative transition between effects of long-range and short-range mate searching, because once males locate females, shortrange pheromones and acoustic cues may influence whether mating occurs (Birch et al 1990;Conner 1999). Further, obviously all of these factors can be strongly influenced by the weather and climate (McNeil 1991;Pellegrino et al 2013), and mate-searching males are known to navigate pheromone plumes of rather complex filamentous structure (e.g., Liu and Haynes 1992). Females can simply modify male arrival rates by choosing not to call (e.g., after mating; Webster and Cardé 1984).…”

Rare patterns of dorsal puncture inPterostichus oblongopunctatus(Coleoptera: Carabidae)

“…A lack or a lower number of such setae in the case of males of P. oblongopunctuatus can be a good confirmation of this hypothesis as their role in reproductive behaviour ends with the act of copulation (Thornhill & Alcock, 1983). Although detailed studies upon the role of elytral setae of this ground beetle species should be done in the future, similar conclusions pointing to modified sexual behaviour based on atmospheric pressure changes (even if based on hygroreceptors located on antennae), which of course are connected to air humidity, were drawn for other insects (Pellegrino et al, 2013). …”

Tiny insects against the weather—flight and foraging patterns of Frankliniella schultzei (Thripidae) not altered by onset of rainfall

“…By contrast, large insects such as butterflies or honeybees are probably adversely affected by rainfall exposure (Pardikes et al ., ; He et al ., ) and possibly need shelter from rain because they suffer a higher impact force from raindrops than do small insects, and are more likely to be splashed, with raindrops breaking apart over the insect body, rather than them rebounding off the drop's surface tension (Dickerson et al ., ). Factors other than size are likely influencing an insect's risk to weather exposure, however, because drosophila fruit flies and aphids, which are closer to thrips in size, both respond to decreasing atmospheric pressure (Ankney, ; Pellegrino et al ., ). Extremes of wind speed or temperature outside the range recorded in our study area could explain variable responses to stormy conditions by insects living in different climates.…”

“…Responses to decreasing atmospheric pressure in the laboratory have been measured as reduced mating frequency in a range of insects, including beetles, moths and aphids (Pellegrino et al ., ), as well as drosophilid flies (Ankney, ). Anecdotal evidence from laboratory work also suggests that thrips become inactive on days with storms (Rafter & Walter, ).…”