Plasticity of olfactory‐guided behaviour and its neurobiological basis: lessons from moths and locusts

Abstract

The sense of smell plays an important role in guiding the behaviour of many animals including insects. The attractiveness of a volatile is not only dependent on the nature of the chemical, but might change with the physiological status (e.g., age/hormone or mating status) or environmental conditions (e.g., photoperiod or temperature) of the individual. Here we summarize our studies focused on the plasticity of olfactory-guided behaviour and its neurobiological basis linked with the physiological status in Lepidoptera and migratory locusts. In moths and locusts, age and juvenile hormone changed the behavioural responses to pheromones. In moths, mating had an effect on pheromone responses in males and plant odour responses in females. In all cases of behavioural plasticity studied, we found changes in the sensitivity of olfactory interneurons in the antennal lobe, whereas the peripheral system does not seem to show any plasticity in that context. Changes in the central nervous system were slow under the influence of juvenile hormone (days) or fast after mating (minutes). The olfactory system seems thus to adapt to the physiological or environmental situation of an animal to avoid a waste of energy. We discuss possible mechanisms underlying the observed plasticity.

Identification of the Sex Pheromone of Copitarsia decolora (Lepidoptera: Noctuidae)

“…The attraction response of male C. decolora to pheromone not only depends on the chemical composition (type of compounds and their relative proportions) (Rojas et al 2006), but is also influenced by insect age and mating status, which affect the sensory input or processing that generates the necessary locomotion pattern to land on the stimulation source (Daly et al 2007;Anton et al 2007;Lemmen & Evenden 2009). In C. decolora males, neural plasticity induced by the physiological state allows males to modulate their response to the sex pheromone, which must be considered before that synthetic pheromone is used to manage this insect.…”

“…However, male response can be affected by numerous factors, including the physiological state of the insect (Anton et al 2007;Evenden & Gries 2008) and experience (Anton et al 2007). Pheromones are detected by olfactory receptor neurons (ORN) housed within cuticular sensilla mainly on the antennae (Keil 1999).…”

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

“…Adult females perceive these odors via specialized olfactory receptor neurons, and use the volatiles as chemical cues to identify suitable plants for feeding and/or oviposition (Anton et al, 2007;Cardé and Willis, 2008;Mustaparta, 2002). Volatile blends differ between plant species both qualitatively and quantitatively (Baldwin et al, 2006;Bruce et al, 2005;Dötterl et al, 2005).…”

Plant odour stimuli reshape pheromonal representation in neurons of the antennal lobe macroglomerular complex of a male moth

“…More specifically, we studied how a behaviourally active plant volatile, heptanal, applied in individual or pulsed stimulations, affects responses of neurons within the MGC to the species-specific sex pheromone blend in the noctuid moth A. ipsilon, which has a well-studied olfactory-guided behaviour and olfactory system [see Anton et al (Anton et al, 2007) and references therein] (Barrozo et al, 2010). This is a crucial question in olfactory research, because the AL output delivers highly processed information, used for behavioural decision-making within higher brain centres.…”