Attraction ofChrysotropia ciliata(Neuroptera, Chrysopidae) Males to P-Anisaldehyde, a Compound with Presumed Pheromone Function

In a field-trapping experiment with plant volatiles, we observed notably high attraction of green lacewing (Chrysotropia ciliata) males to the compound p-anisaldehyde. Based on this finding, we initiated the present study to elucidate this phenomenon and to investigate the chemical ecology ofC. ciliata.Scanning electron microscopy revealed elliptical glands abundantly distributed on the 2nd to 6th abdominal sternites ofC. ciliatamales, whereas females of the species completely lacked such glands. No p-anisaldehyde was found in extractions of body parts ofC. ciliata.Methyl p-anisate and p-methoxybenzoic acid were identified exclusively in the extract from abdominal segments 2-8 of males. Field-trapping experiments revealed no attraction ofC. ciliatato either methyl p-anisate or p-methoxybenzoic acid. In contrast, males showed marked attraction to p-anisaldehyde in the field and antennae showed strong responses to this compound. Headspace collections in the field from living insects in their natural environment and during their main daily activity period indicated that p-anisaldehyde was emitted exclusively byC. ciliatamales. Our overall results suggest that p-anisaldehyde might serve as a male-produced pheromone that attracts conspecificC. ciliatamales. Here, we discuss hypotheses regarding possible mechanisms involved in regulation of p-anisaldehyde production, including involvement of the compounds methyl p-anisate and p-methoxybenzoic acid, and the potential ecological function of p-anisaldehyde inC. ciliata.