Chemical ecology of the palm weevilRhynchophorus palmarum (L.) (Coleoptera: Curculionidae): Attraction to host plants and to a male-produced aggregation pheromone

Abstract

Attraction to host plants by adultRhynchophorus palmarum (L.) palm weevils was studied in the field and in the laboratory. Chemical analysis revealed the presence of ethanol and ethyl-acetate in stems of coco palms and in pineapple fruits and of pentane, hexanal, and isopentanol in coco stems. In the olfactometer, the first two compounds and isoamyl-acetate were attractive to the insects and the last three compounds, although not attractive by themselves, increased attractiveness when mixed with the first two compounds. Mixtures of these compounds, in proportions similar to the one occurring in attractive plant tissue, were as attractive as natural coconut tissue. In the field, the chemical compounds, either presented alone or as a mixture, did not attract the weevil. Males produce an aggregation pheromone when smelling ethyl-acetate. Rhynchophorol, 2(E)-6-methyl-2-hepten-4-ol, the known active component of the aggregation pheromone, attracts weevils in the olfactometer and in the field only if plant tissue, ethyl-acetate, or the above-mentioned odor mix are present. We propose that a complex mix of ethanol, ethyl-acetate, pentane, hexanal, isolamyl-acetate, and/or isopentanol serve as a short-range orientation cue to fresh wounds on the plant and that additional host odors, attracting weevils from a distance, have still to be discovered. Rhynchophorol can be considered to be a Synergist, having an anemotactic action at a distance. We recommend the use of retention traps baited with rhynchophorol, ethyl-acetate, and sugar cane as an alternative control method for the pest.

Correspondence between rates of host plant consumption and responses to the Acalymma vittatum male‐produced aggregation pheromone

“…Host plant volatiles alone (e.g. Hughes, 1973b;Jaffe et al, 1993) or hormonal changes triggered by midgut expansion (Hughes & Renwick, 1977) can stimulate male pheromone release, or perhaps pheromone composition may be altered by feeding as it can be by beetle density (Pierce et al, 1989). These relationships remain to be clarified for A. vittatum.…”

“…There are numerous examples of host plant volatiles that are potent synergists to male pheromone signals (e.g. Wood, 1982;Dickens, 1989;Bartelt et al, 1990;Dickens et al, 1990;Jaffe et al, 1993;Raffa et al, 1993, and references therein;Bartelt, 1999). Although evidently not essential for A. vittatum signalling (as males feeding on pollen did attract), synergy with host volatiles could account for increased attraction with the rate of cucurbit feeding.…”

Insect pheromone research in South America

“…They also found that the aggregation pheromone [(E)-6-methyl-2-hepten-4-ol, rhynchophorol] only attracts males when either the complete bouquet of plant volatiles or ethyl acetate alone is present. 109 Metamasius hemipterus is a serious sugarcane pest distributed throughout Central and South America, the West Indies, Mexico and Florida (U.S.). The attraction of adult beetles toward host plant parts in an olfactometer was reported, 110 as well as captures in field traps baited with different mixtures of plant parts and the aggregation pheromone, an 8:1 mixture of 4-methyl-5-nonanol and 2-methyl-4-heptanol.…”

Ocorrência e controle de Curculionidae em Cocos nucifera L. em Sinop, Mato Grosso

“…Originado no sudeste da Ásia foi introduzida no Brasil através do estado da Bahia (MIRISOLA FILHO, 2002), sendo esse, segundo o IBGE (2009), o maior produtor brasileiro com 79.596 ha, produção de 467.080 toneladas e produtividade de 5.868 kg/ha.…”