Sex-Specific Allometry of Morphometric and Reproductive Traits in Oriental Fruit Flies (Diptera: Tephritidae)

The oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), is a highly invasive and polyphagous pest of many horticultural crops in the world, and is currently present in Asia, Africa, and Oceania. To provide essential knowledge for quality control in mass-rearing programs for sterile insect technique against the pest, we investigated how adult body weight and hind-tibial length were correlated in each sex and how body size of each sex affected lifetime reproductive fitness. We show that body weight and hind-tibial length were significantly positively correlated in both sexes, indicating that either trait can be used as an index of body size. However, the weight-tibial length relationships were sex specific, with females gaining disproportionally more weight than males with the increase of hind-tibial length. Body size was not significantly correlated with longevity of either sex, but males lived significantly longer than females. Larger females laid significantly more eggs regardless of body size of the male partner, suggesting that male size has no effect on fecundity. However, body size of both sexes had a significant effect on fertility. We conclude that selection on body size-reproductive fitness relations operates in different directions for the two sexes of B. dorsalis, with larger females and average males having highest reproductive fitness.