Mating Sequence and Evidence for the Existence of a Female Contact Sex Pheromone in Brontispa longissima (Coleoptera: Chrysomelidae)

Abstract

To clarify the presence of a pheromone in Brontispa longissima (Coleoptera: Chrysomelidae), we observed its mating behavior and conducted a series of bioassays. When male and female B. longissima came in contact, the male was observed to hold and mount the female, extend its penis toward her abdominal tip, and copulate. The male was observed to hold the female only after he had touched her with his antennae and/or forelegs. Males showed similar mating attempts toward females killed by freezing. On the other hand, no males showed mating attempts toward females washed with hexane, but they did toward females washed with hexane and re-treated with hexane extract of the female body or female elytra. Furthermore, males showed similar mating attempts toward a glass dummy treated with a solvent extract of female elytra. These results indicate the presence of a female sex pheromone that is perceptible by direct contact and plays an important role in mating in B. longissima. When the crude extract of female elytra was subjected to silica gel chromatography, only the fraction eluted with hexane elicited mating behavior in males. Furthermore, when the active fraction was chromatographed on AgNO 3 -impregnated silica gel, only the fraction eluted with hexane elicited mating behavior in males. The contact sex pheromone of B. longissima is therefore believed to consist of one or more less-polar compounds, probably saturated hydrocarbons.

Antennal and abdominal transcriptomes reveal chemosensory gene families in the coconut hispine beetle, Brontispa longissima

“…In alignment with other beetles, the behaviors of B. longissima are olfactory sense driven and olfaction is important for host tree selection, aggregation and colonization. Additionally, it has been reported that the ratios of key components of the coconut palm leaf volatiles elicit attraction, aggregation and oviposition by this beetle 26 , 27 . Therefore, a better understanding of the molecular components involved in olfactory perception in this pest will increase opportunities to develop highly effective surveillance and control strategies against this beetle.…”

Age in Relation to Copulation, Egg Development, and Multiple Mating Behavior in the Coconut Palm Pest Brontispa longissima (Coleoptera: Chrysomelidae)

“…Kawazu et al (2011) reported that males did not attempt to copulate with females that had been washed with hexane solvent. When the washed females were retreated with the hexane extract from a female body or female elytra, males resumed attempts to copulate, indicating the likely role of a female contact sex pheromone ) that we suggest is present on females regardless of age.…”

“…All observations of copulation were performed as described by Kawazu et al (2011). One male and one female were placed on a Þlter paper sheet (76 by 26 mm) surrounded by 2-mmthick slide glasses.…”

Polyandry increases reproductive performance but does not decrease survival in female Brontispa longissima

“…All observations of copulations were performed as described by Kawazu et al . (2011). In all cases, one 3-week-old virgin male and one 0-week-old initially virgin female were placed on a filter paper sheet (76 × 26 mm 2 ) (width × length) surrounded by glass (2 mm thick, placed on top).…”