Plant odor and sex pheromone are integral elements of specific mate recognition in an insect herbivore

Abstract

Specific mate recognition relies on the chemical senses in most animals, and especially in nocturnal insects. Two signal types mediate premating olfactory communication in terrestrial habitats: sex pheromones, which blend into an atmosphere of plant odorants. We show that host plant volatiles affect the perception of sex pheromone in males of the African cotton leafworm Spodoptera littoralis and that pheromone and plant volatiles are not perceived as independent messages. In clean air, S. littoralis males are attracted to single synthetic pheromone components or even the pheromone of a sibling species, oriental cotton leafworm S. litura. Presence of host plant volatiles, however, reduces the male response to deficient or heterospecific pheromone signals. That plant cues enhance discrimination of sex pheromone quality confirms the idea that specific mate recognition in noctuid moths has evolved in concert with adaptation to host plants. Shifts in either female host preference or sex pheromone biosynthesis give rise to new communication channels that have the potential to initiate or contribute to reproductive isolation.

Chemical cues and genetic divergence in insects on plants: conceptual cross pollination between mutualistic and antagonistic systems

“…Researchers have long recognised the ability of varietal types to confer different levels of resistance to insect herbivores and/or attraction to natural enemies. Furthermore, chemotypes appear to correspond well to taxonomic entities, genotypes and environments [20,21]. This variation forms the basis for the specialisation of insect herbivores within plant populations.…”

“…Furthermore, plant volatiles can signal appropriate oviposition sites [17] and interact with herbivore sex pheromones to mediate reproduction [18], this is especially relevant for herbivores mating on their hosts. In some cases, both plant volatiles of the undamaged host plant and adult sex pheromones are needed, which further links mate selection and oviposition cues and provides a mechanism for strengthening assortative mating and ecological divergence of herbivores across plant species [19,20].…”

Insect Odorscapes: From Plant Volatiles to Natural Olfactory Scenes

“…When presented with calling females in a clean air background in a no-choice situation, male S. littoralis were attracted toward females of the sibling species S. litura almost as much as to conspecific females (Saveer et al, 2014). However, while the addition of host plant (cotton) odor did not affect their attraction toward conspecific signals (either synthetic full pheromone blend or calling female), it significantly reduced attraction toward heterospecific signals (either main pheromone component alone or S. litura calling female) (Borrero-Echeverry et al, 2018).…”

Effects of plant extracts and essential oils on the behavior of Acrobasis advenella (Zinck.) caterpillars and females

“…They can contribute to indicate food, decide about mating sites and control reproduction processes; furthermore, they are involved in food selection and acceptance of individual plants or only their parts, but also plants that are inappropriate for adult or larval food. Female insects also use plant volatiles to select oviposition sites (Nansen and Phillips 2003;Borrero-Echeverry et al 2018). Oviposition by females is particularly important for the survival of their progenies, mainly because the quality of food and its availability to larvae are determined by oviposition of the female on a suitable host plant (Honda 1995).…”