Effect of methoprene application, adult food and feeding duration on male melon fly starvation survival

The application of methoprene and access to protein in adult diet has been shown to enhance mating success in male melon fly Bactrocera cucurbitae Coquillett (Diptera: Tephritidae), supporting their incorporation into operational area-wide programmes integrating the Sterile Insect Technique (SIT). The objective of the present study was to investigate the effect of methoprene, diet including protein and feeding days on male starvation survival to determine the minimum number of feeding days required prior to male release in the field. The study was performed in the laboratory by treating males with (i) both protein and methoprene (M+P+), (ii) only protein (M-P+), (iii) only methoprene (M+P-) or (iv) untreated (M-P-). The males were starved after exposure for an increasing number of days (1-7) to their respective treatment. Mean longevity was highest after 3-day post-emergence feeding duration for M+P+, M+P- and M-P- males, but 4days of feeding for M-P+ males. Additional feeding days after 4days, did not increase male survival and feeding for 7days decreased starvation survival of sugar-fed males. Application of methoprene and/or access to diet including protein had no adverse effect on starvation survival but feeding duration had a significant positive effect on starvation survival. To the contrary, the current study provides a strong evidence for the benefits of methoprene application and protein incorporation into the adult diet of sterile males. Treated males achieve higher sexual success, reach sexual development several days earlier, and are therefore much closer to sexual maturity when released in SIT action programmes after being held in the fly emergence and release facility for a post-emergence feeding duration of at least 3days.