# A Pre-Exposure to Male-Specific Compound γ-Hexalactone Reduces Oviposition in Bactrocera oleae (Rossi) (Diptera: Tephritidae) Under Laboratory Conditions

## TL;DR

Exposing female olive fruit flies to a male-specific compound before mating reduces their egg-laying, suggesting a potential new pest control method.

## Contribution

Demonstrates that pre-exposure to γ-hexalactone disrupts oviposition in olive fruit flies.

## Key findings

- A 24-hour pre-exposure to 1.0 mg of γ-hexalactone significantly reduced egg-laying in female olive fruit flies.
- Females pre-exposed to 0.5 mg of γ-hexalactone showed a reduced but not significant decrease in oviposition.
- The study provides a basis for exploring γ-hexalactone as an oviposition disruptant in pest management.

## Abstract

Laboratory trials have been undertaken to determine the effect of the pre-exposure to γ-hexalactone, a specific compound released by virgin males of Bactrocera oleae (Rossi) (Diptera: Tephritidae), on the oviposition activity of the species. After pre-exposing virgin females to 1.0 mg of γ-hexalactone for 24 h, we observed that the number of eggs laid on an artificial substrate after mating was significantly reduced, whereas no significant differences were observed with a previous experience to 0.5 mg of compound. These results are of particular interest for delving into the possibility of using intraspecific semiochemicals as oviposition disrupting tools in the olive fruit fly, although more research is still needed to gain a deeper knowledge about the effect of a previous experience to γ-hexalactone on the behavior of the species.

The olive fruit fly Bactrocera oleae (Rossi) (Diptera: Tephritidae) is regarded as the most harmful pest insect for olive trees worldwide. In order to control olive fruit fly populations and mitigate the damage and economic losses they produce, the development of novel strategies to control the olive fruit fly within an integrated pest management scope has become a major concern. Here we show that a 24-h pre-exposure to the male-specific γ-hexalactone significantly reduces the oviposition on an artificial substrate. The number of eggs per female laid by those females pre-exposed to 1 mg of γ-hexalactone was significantly reduced (6.8 ± 6.1 eggs/female) in comparison to naïve (i.e., non-exposed) females (22.4 ± 10.9 eggs/female), yielding a mean oviposition activity index (OAI) of −0.56 ± 0.22. Contrarily, no significant effect was observed when females were pre-exposed to 0.5 mg of compound, even though the number of eggs per female (14.2 ± 6.3) was lower than that of naïve females, resulting in a mean OIA of −0.24 ± 0.17. Overall, this research represents a preliminary basis for delving into the potential of γ-hexalactone for being used as an oviposition disruptant, albeit further research is still required to address this issue.