Field evaluation of female- and male-targeted traps for Ceratitis capitata (Diptera: Tephritidae)

Abstract

Mediterranean fruit fly (Medfly) Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) is a globally significant economic pest for which lure based trapping can be used to monitor established populations and for surveillance. Either female- or male-targeted traps can be used; however, recommendations on which to apply are inconsistent and many programs rely on male-targeted traps. Here, we compare the performance of male-targeted traps (Lynfield Trap with Trimedlure) and female-targeted traps (Biotrap Globe trap with the 3-component lure-TMA Plus) in apple orchards in south-west Western Australia over 2 years (September 2019 to September 2021). Male-targeted traps caught more Medflies overall than female-targeted traps, although the difference was minor. However, female-targeted traps were better at attracting Medfly early in the season when populations were small; and were more likely to capture at least one fly when their paired male-targeted trap caught none. Conversely, male-targeted traps were more likely to capture Medflies late in the season and were more likely to catch high numbers of Medflies. Consequently, female-targeted traps may be better at detecting Medfly early in the season, and male-targeted traps may be better at detecting Medfly abundance late in the season, at least in apple orchards. Our results suggest that either or both trap-types could be used for monitoring Medfly populations, with the optimal solution being dependent on the intended application.

Keywords: attractant; ecology andand population dynamics; horticultural entomology; monitoring; surveillance.

Fig. 1.

A map of southwest Western Australia, with stars indicating the location of trapping localities.

Fig. 2.

Male-targeted Lynfield trap baited with 3g trimedlure cone (left) and female-targeted Biotrap Version 2 X trap baited with TMA Plus Unipack—3 component lure (right).

Fig. 3.

The percentage of traps (with 95% prediction interval) that caught no Medflies in relation to trap catch in the paired trap (male-targeted: dashed line; female-targeted: solid line), as estimated using binomial GLM.

Fig. 4.

Mean monthly Medflies per trap per day (FTD) caught medflies from female-targeted and male-targeted traps, pooled across the 3 localities and 2 years. Bayesian 95% credible intervals are given, as well as significance between trap targets (* denotes < 0.05, ** < 0.01, and ***<0.001).

Fig. 5.

Mean monthly Medflies per trap per day (FTD) in female-targeted traps and male-targeted traps at the 3 localities, averaged across the 2 years. Gray shading indicates the timing of the harvest season of apples at each locality. Bayesian 95% credible intervals are given, as well as significance between trap targets (* denotes < 0.05, ** < 0.01, and ***<0.001). Note the different scales on the y-axis for each locality; consistent horizontal grid lines with 0.05 FTD spacing are given to enable comparisons of scale across localities.

Fig. 6.

Total sex ratio (F:M) caught in male and female-targeted traps across the 2 years. No Medflies were caught in Sep or Oct in either season. Error bars show the Jeffreys 95% confidence interval for the binomial proportions.