Chemical characterization of fruit and fungal volatiles attractive to dried-fruit beetle,Carpophilus hemipterus (L.) (Coleoptera: Nitidulidae)

Abstract

The chemical basis underlying orientation to fruit and fungal odors was investigated for the dried-fruit beetle,Carpophilus hemipterus (L.). In wind-tunnel bioassays of walking and flight response from 1.8 m, beetles were attracted to odors of the yeastSaccharomyces cerevisiae on agar, aseptic banana, or banana inoculated withS. cerevisiae, although both banana substrates elicited greater response than the yeast alone. When presented in a two-choice bioassay, the yeast-inoculated banana attracted approximately twice as many beetles as did the aseptic banana. GC-MS analysis of the headspace volatiles above these odor sources revealed a somewhat more complex and concentrated volatile profile for yeast-inoculated banana than for aseptic banana. The odor from yeast on agar had fewer components, and these were present at lower concentrations than the odors of either banana substrate. By blending mineral-oil or aqueous solutions of the 18 components of inoculated-banana odor in varying concentrations, it was possible to mimic closely the headspace profile of the natural odor. This synthetic odor also elicited beetle attraction in the wind tunnel at levels comparable to the inoculated banana. Through a series of bioassays in which individual components were subtracted from or added to a synthetic odor blend, it was determined that ethyl acetate, acetaldehyde, 2-pentanol, and 3-methylbutanol comprised the simplest blend of compounds evoking full behavioral response. However, 2-methylpropanol or butanol were apparently interchangeable with 3-methylbutanol in this blend, and comparable response could also be elicited by replacing acetaldehyde with a combination of both 2-pentanone and 3-hydroxy-2-butanone. Thus, our results suggest that this generalist insect herbivore locates its hosts by a long-range response to a variety of blends of common fruit volatiles, whose concentrations are enhanced by fungi.

Identification of food volatiles attractive to dusky sap beetle,Carpophilus lugubris (Coleoptera: Nitidulidae)

“…Thirty-gram samples of whole-wheat bread dough inoculated with baker's yeast or similar samples of fruits were incubated in 240-mt Qorpak straight-sided jars at room temperature for about 24 hr or five to seven days, respectively, before being used for volatile collections or for bioassays. Fresh tomato, banana, sweet corn, and strawberry were maintained aseptically or inoculated using a previously described method (Phelan and Lin, 1991) with either Saccharomyces cerevisiae or Candida krusei, two yeasts that are ubiq-uitous in nature (Alexopoulos, 1979). The lid of each jar was installed with a 37-mm Bacterial Air Vent (Gelman Science, Ann Arbor, Michigan) for ventilation, and a sleeve-type rubber septum (Thomas Scientific) for collection of headspace samples.…”

“…Headspace volatiles were trapped on Tenax GC and then thermally desorbed to a capillary gas chromatograph (Phelan and Lin, 1991). Due to the high concentration and volatility of ethanol and acetaldehyde relative to the other odor components, two volatile collection methods were used.…”

Behavioural and electrophysiological responses of the phlebotomine sandfly Lutzomyia longipalpis (Diptera: Psychodidae) when exposed to canid host odour kairomones

“…The ascoid sensilla of L. longipalpis can house between three and eleven olfactory receptor cells and other olfactory sensilla also occur on the antenna (M. Vlimant and P. A. Diehl, unpublished data). The dried fruit beetle, Carpophilus hemipterus (L), is a generalist herbivore and is known to respond in a wind tunnel to eighteen chemical components of banana odour (Phelan & Lin, 1991). The simplest blend that induced a full behavioural response contained at least four compounds representing three functional groups.…”

Composition of volatiles from fermenting pollen dough and attractiveness to the small hive beetleAethina tumida, a parasite of the honeybeeApismellifera

“…Thus the lower attractiveness of the pollen dough conditioned for 14 days is suggestive of the disappearance of attractant and the appearance of repellent compounds in the volatiles, and possibly an antagonistic interaction between the yeast associated with the SHB and a different microorganism. Interestingly, acetaldehyde, ethanol, ethyl acetate and several of these ethyl esters have been identified in volatiles released by microbial cultures, and these volatiles either act alone as kairomones or synergize the activity of pheromones in various nitidulid species (Smilanick et al, 1978;Lin and Phelan, 1991;Phelan and Lin, 1991;Bartelt et al, 1993;James et al, 1996;Nout and Bartelt, 1998;Bartelt and Zilkowski, 1998;Zilkowski et al, 1999;Teal et al, 2006). Strikingly, 2-phenylethanol, also a fermentation product (Zilkowski et al, 1999, Zhu et al, 2003, is the major component of volatiles released by pollen dough conditioned for 14 days.…”