Identification of Components of Male-Produced Pheromone of Coffee White Stemborer, Xylotrechus quadripes

Abstract

The coffee white stem borer, Xylotrechus quadripes Chevrolat (Coleoptera: Cerambycidae), is the foremost pest of arabica coffee in India, Sri Lanka, China, Vietnam, and Thailand. Previous work showed that female beetles were attracted to traps baited with male beetles. Analyses of volatiles from male X. quadripes of Indian origin by gas chromatography (GC) linked to electroantennographic (EAG) recording from a female beetle antenna showed three male-specific components comprising more than 90% of the volatiles, two of which elicited EAG responses. The major EAG-active component was produced at up to 2 microg hr(-1) insect(-1) and was identified as (S)-2-hydroxy-3-decanone (I) by comparison of GC data, and mass (MS), infrared, and nuclear magnetic resonance (NMR) spectra with those of synthetic standards. The second component was identified as 3-hydroxy-2-decanone (II) produced in part by isomerization of I under the conditions of the GC analysis, although the NMR spectrum suggested it is naturally produced at up to 7% of I. The minor component that elicited an EAG response, present at 7% of the amount of I, was identified as (S,S)-2,3-dihydroxyoctane (III) from GC and MS data. 2-Hydroxy-3-octanone (0.2-0.5% of I), 2,3-decanedione (2% of I), 2-phenylethanol (3% of I), and octanoic acid (4% of I) were also identified in volatiles from male beetles. A general, stereospecific synthetic route to the enantiomers of 2-hydroxy-3-alkanones from the enantiomers of ethyl lactate was developed. The enantiomers of III were synthesized from (E)-2-octene by Sharpless asymmetric dihydroxylation. (S)-(I) was attractive to male X. quadripes in laboratory bioassays, but addition of (S,RS)-(III) at 10% of I reduced attractiveness. In field trials carried out in India with sticky, cross-vane traps, (S)- and (RS)-(I) attracted male X. quadripes and addition of (S,S)-(III) at 10% of I reduced attractiveness. Significant numbers of female Demonax balyi Pascoe (Coleoptera: Cerambycidae) were sometimes caught in traps baited with (S)-(I) alone.

Sex Pheromones and Their Impact on Pest Management

“…Male beetles have been shown to attract females, and (S)-2-hydroxy-3-decanone has been identified as the main attractive compound. Pheromone traps have been rapidly adopted for mass trapping (Table 1; Hall et al 2006) reflecting exceptional grower interest in the absence of acceptable alternative control methods.…”

Female calling and male flight orientation and searching behaviors in Callisphyris apicicornis: evidence for a female-produced sex attractant pheromone

“…In these species, males tend to be stationary during calling , while adopting a "push-up stance" with the front legs extended and both the head and thorax raised. There are also a number of reports of male-produced pheromones (e.g., Hall et al, 2006;Ray et al, 2006). On the other hand, calling behavior by females has been less commonly reported for cerambycid beetles and has been described in detail in only a few cases.…”

Predicted taxonomic patterns in pheromone production by longhorned beetles

“…Femaleproduced pheromones have been identified for two species whose taxonomic affiliation with the Cerambycidae is uncertain: Migdolus fryanus Westwood and Vesperus xatarti Dufour (Leal et al 1994;Boyer et al 1997;see Napp 1994;Bense 1995;Dong and Yang 2003). Maleproduced volatile sex or aggregation pheromones have been conclusively identified in five species in three tribes of the subfamily Cerambycinae, Xylotrechus pyrrhoderus Bates, Xylotrechus quadripes Chevrolat, and Neoclytus acuminatus acuminatus (F.) of the Clytini (Sakai et al 1984;Lacey et al 2004;Hall et al 2006), Anaglyptus subfasciatus Pic of the Anaglyptini (Leal et al 1995), and Hylotrupes bajulus (L.) of the Callidiini . Pheromones of these species share a structural motif: hydroxyl or carbonyl groups at carbons two and three in straight-chains of six, eight, or ten carbons (Lacey et al 2004).…”

“…All of the cerambycine species that produce volatile pheromones have relatively short antennae for cerambycids, much shorter than their body length (see Sakai et al 1984;Fettköther et al 1995;Leal et al 1995;Lacey et al 2004;Hall et al 2006). The elongate antennae of other cerambycid species, the "longhorned beetles" for which the family is named, apparently are adaptive because males recognize females by antennal contact chemoreception, and the probability of finding a mate is determined by area search rate (Hanks et al 1996a;Hanks 1999).…”