Temperature modulation of behavioural thresholds controlling male moth sex pheromone response specificity

Abstract

ABSTRACT. The response specificity of male Oriental fruit moths, Grapholita molesta (Busck) and pink bollworm moths, Pectinophora gossypiella (Saunders), to different blends and doses of pheromone is altered dramatically by temperature. When acclimated and tested in a flight tunnel at 20oC males of both species exhibit a high degree of specificity, with peak response levels occurring to a narrow range of blend‐dose combinations close to the natural blend. When tested at 26oC, however, males exhibit a significantly lower degree of specificity, with peak response occurring to a broader range of treatments. The change in response specificity results from shifts in behavioural threshold effects influencing plume orientation and initiation of upwind flight, as well as from arrestment of upwind flight, occurring later in the flight sequence. The observed changes in male behaviour suggest that the effect of temperature is directly on neural pathways involved in the perception of odour, and not simply the result of an increase in motor activity or a significant change in the release rate of the pheromone. The results support the threshold hypothesis for pheromone perception (Roelofs, 1978) as a general principle in the Lepidoptera, but also show that the degree of response specificity can be significantly affected by temperature.

Behavioral and neurophysiological responses of an insect to changing ratios of constituents in host plant-derived volatile mixtures

“…Affixed natural ratio between different constituents of a blend is considered crucial in chemical communication between organisms including insect-mammal (Takken et al, 1997), insect-human (Silva et al, 2005), predator-prey (Steullet et al, 2002), male-female insect (Cardé and Minks, 1995;Linn et al, 1988;Witzgall et al, 2008) and insect-plant interactions (Bruce et al, 2005;Visser, 1986). For male-female interactions in insects, empirical evidence substantiates that the affixed natural ratio of compounds in female-released pheromone blends determines the specificity of this chemical signal to males (Anton et al, 1997;Christensen et al, 1991;Jarriault et al, 2009;Linn et al, 1988;Linn et al, 1991;Löfstedt et al, 1991;Minks and Cardé, 1988).…”

Fitness effects of thermal stress differ between outcrossing and selfing populations inCaenorhabditis elegans

“…Hence, we hypothesize that the higher thermal sensitivity of obligatorily outcrossing lines may be associated with mating failure. Temperature is well-known to affect behavior of ectotherms (reviewed by Angiletta 2009) including reproductive behavior in many species (Wilkes 1963;Linn and Campbell 1988;Katsuki and Miyatake 2009). Whereas self-fertilization is a purely physiological process, outcrossing requires a complex set of behaviors in C. elegans.…”

Will climate change affect insect pheromonal communication?

“…For instance, male moths C. fraxinella reared under increased temperature during their reproductive diapause and subsequently exposed to female sex pheromones in a wind tunnel show more pronounced sexual responses [39]. At higher temperatures, male moths also show a lower level of specificity towards their sex pheromones, due to shifts in behavioural thresholds related to plume orientation and to the elicitation of upwind flight [51].…”

“…For instance, male moths C. fraxinella reared under increased temperature during their reproductive diapause and subsequently exposed to female sex pheromones in a wind tunnel show more pronounced sexual responses [39]. At higher temperatures, male moths also show a lower level of specificity towards their sex pheromones, due to shifts in behavioural thresholds related to plume orientation and to the elicitation of upwind flight [51].With regards to the impact of atmospheric CO 2 concentration, the escape behaviour of aphids reared under elevated CO 2 concentrations (i.e. 2100 predicted levels) is lower compared to those reared under ambient CO 2 conditions [52,53,54 ].…”