Chemosensory basis of feeding and oviposition behaviour in herbivorous insects: a glance at the periphery

Abstract

Recent advances in our understanding of the relationship between chemosensory and behavioural responses to phytochemicals come from a number of studies on ovipositional and food selection behaviour of flies, butterflies, moths and beetles. Establishing input‐output relationships has provided insight into the way in which the activity of chemoreceptors is translated into host‐plant selection behaviour. This was achieved for both the qualitative contrast acceptance/rejection and for quantifiable preference hierarchies. By now it is clear that the subtlety of coding the complex phytochemical profiles offered by potential host plants relies on across‐fibre patterns or ensemble‐firing of taste neurons. Progress along these lines depends on unravelling processing pathways in the central nervous system, still a largely unexplored area in herbivorous insects. Increased interest can be noted for the mechanisms operating during the most peripheral events of chemoreception: the interaction of phytochemical and chemoreceptor, determining the specificity of recognition. Evidence for ‘peripheral integration’ has accumulated. Deterrent receptors have an especially puzzling nature. Although such cells respond to a wide array of structurally diverse secondary plant metabolites, their sensitivity profile differs between closely related species. To what extent membrane‐bound receptor molecules are involved and what degree of specificity is conferred by these, is largely unknown. Sensitivity to a certain group or class of compounds is determined by single genes in several cases. This allows for a scenario in which single gene mutations affect stimulus‐receptor interactions, which might concurrently affect host‐plant selection behaviour.

Antifeedant activity of citrus limonoids against Colorado potato beetle: comparison of aglycones and glucosides

“…Recent studies suggest that beetle chemosensory responses to allelochemicals involve disruption or inhibition of the taste cells normally responding to plant feeding stimulants (van Loon, 1996). Our finding of the drastic change in activity associated with changes in the A-and D-rings suggests a chemical-receptor mediated pathway to antifeedant activity in Colorado potato beetle.…”

Antifeeding effects of azadirachtin on the fifth instar Spodoptera litura larvae and the analysis of azadirachtin on target sensilla around mouthparts

“…There are more dendritic branches in the sensilla, indicating that sensillum basiconicum are typical sensilla (Shanbhag, Müller, & Steinbrecht, 1999). The sensilla basiconica has the function of smell and taste, and thus reacts to food stimuli (Loon, 1996). To determine the main sensilla and the effect of azadirachtin on S. litura larvae, four main sensilla were treated with azadirachtin.…”

“…Lepidoptera larvae mainly select host plants by head sensilla, and then show feeding behavior. It is helpful to understand the feeding mechanism of insects by studying head sensilla of Lepidoptera larvae (Loon, ).…”

Specificity of a Y‐linked gene in the flea beetle Phyllotreta nemorum for defences in Barbarea vulgaris

“…A large number of phytophagous insect species are food specialists with a narrow host plant range (Thompson, 1994). Specialization may make host plant finding more critical, and many insects have developed refined sensory receptors and behavioural responses which enable them to find their particular host plants among other green plants in their habitat ( van Loon, 1996). The selection pressures which have promoted the evolution of host plant specialization are poorly known (Bernays & Graham, 1988;Futuyma & Keese, 1992;Thompson, 1994).…”