Attraction of the grasshopper, Melanoplus sanguinipes, to host plant odors and volatile components

Abstract

The attraction of the polyphagous grasshopper, Melanoplus sanguinipes (F.), to odors from plant foliage or to chemical components of these odors was tested in a glass Y‐tube olfactometer. Humidified air was passed at equal flow rates through a sample chamber containing plant material and an empty control chamber and then through the Y‐tube to the holding chamber containing the test insect. Solutions of volatile chemicals in water were metered at a constant rate into the sample air stream with a syringe pump. Insects moving upwind were recorded after entering either the sample or control arm of the Y‐tube. Both nymphs and adults were strongly attracted to the odor of chopped and intact seedling foliage of perennial ryegrass and wheat. Chopped leaves but not intact leaves of sorghum and alfalfa also were significantly attractive. The major components of ryegrass odor from both chopped and stem‐cut leaves were Z‐hex‐3‐en‐1‐yl acetate, Z‐hex‐3‐en‐1‐ol, and pent‐1‐en‐3‐ol, in that order, with lesser amounts of E‐hex‐2‐enal. Chopped leaves released many more minor components. The major components when tested individually or in binary and ternary mixtures were significantly attractive to grasshoppers compared to humidified air but not to the degree of whole plant odor. However, a quartenary mixture simulating the odor blend had levels of attractancy equal to that of chopped grass odor. Blends of these 5‐ and 6‐carbon unsaturated alcohols, esters, and aldehydes volatilizing from green plants probably play an important role as olfactory cues for orientation of grasshoppers to food plants. Résumé Attraction de Melanopus sanguinipes par des odeurs de feuillage de plantes et par leurs composés volatiles L'attraction de M. sanguinipes (F.) par l'odeur du feuillage et des composés chimiques de ces odeurs a été examinée dans un olfactomètrc en tube de verre en Y. Des flux identiques d'air humidifié étaient introduits dans une enceinte contenant le matériel végétal et dans une enceinte témoin, et, via le tube en Y, dans l'enceinte contenant l'insecte à étudier. Des solutions aqueuses de substances volatiles étaient introduites à un taux constant dans le courant d'air grâce à une seringue. Les insectes se déplaçant contre le vent étaient enregistrés après pénétration dans une branche déterminée du tube en Y. Larves et adultes étaient fortement attirés par l'odeur de feuillage intact ou coupé de semis de Lolium perenne et de blé (Triticum aestivum). Les feuilles coupées, mais non les fcuilles intactes de sorgho (Sorghum bicolor) et de luzerne (Medicago sativa) étaient, elles aussi, significativement attractives. Les principales substances constituant de l'odeur de feuilles de Lolium perenne, tant coupées qu'intactes, étaient dans l'ordre de Z‐hex‐3‐en‐1‐yl acétate, le Z‐hex‐3‐en‐1‐ol et le pent‐1‐en‐3‐ol, et dans une moindre mesure, E‐hex‐2‐enal. Les feuilles coupées libéraient beaucoup plus de composés secondaires. Les principaux constituants testés, seuls ou en mélanges binaires ou ternaires, étaient significativement a...

Neural correlates of behavior in the mothManduca sextain response to complex odors

“…Behavioral and electrophysiological studies have demonstrated repeatedly that mixtures are discriminated from their single constituents (52)(53)(54) and that certain components of a mixture are more salient than others (54)(55)(56). Indeed, our findings showed that the odorants Bea, Lin, and especially Bol are important, although individually they do not evoke the behavior of interest.…”

Network architecture underlying maximal separation of neuronal representations

“…Hence as different KCs respond specifically to various and different chemicals (or classes of chemicals), proper wiring of connections and selection/tuning of their strengths can generate high-level, invariant and “meaningful” representations. For example, a hypothetical downstream neuron responding only to odors associated with locust foods could easily be constructed by connecting onto it only KCs firing in response to various 5- and 6-carbon chained alcohols, aldehydes, and esters which are common odorants in grassy plants (cheerfully nicknamed “green odors”; Hopkins and Young, 1990; Bernays and Chapman, 1994). Similarly, some downstream neurons can respond to odors indicating plant toxicity (for examples of such chemical cues see Cottee et al, 1988).…”

Identification of Behaviourally Active Components from Maize Volatiles for the Stemborer Parasitoid Cotesia flavipes Cameron (Hymenoptera: Braconidae)

“…The behaviourally active compounds identified in the maize volatiles have been found to be attractants for certain phytophagous insect species (reviewed by Visser, 1986;Hopkins and Young, 1990) and some hymenopteran parasitoids (Whitman and Eller 1990;Turlings et al, 1991ab;Steinberg et al, 1993;Agelopoulos and Keller, 1994a;Geervliet et al, 1994). (E)-4,8-Dimethyl-1,3,7-nonatriene had earlier been shown to be attractive to Co. flavipes (Ngi-Song, 1995) and recently, it was found to be an attractant for the indigenous hymenopteran parasitoid, Cotesia sesamiae (Cameron) (Khan et al, 1997), which is in agreement with our laboratory results for Co. flavipes.…”