MATING AND REMATING OF MEDFLIES (DIPTERA: TEPHRITIDAE) IN GUATEMALA: INDIVIDUAL FLY MARKING IN FIELD CAGES

Authors: McInnis, Donald; RENDON, P - APHIS - GUATEMALA; Komatsu, Jason

Submitted to: Florida Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/15/2001
Publication Date: 3/30/2002
Citation: Mcinnis, D.O., Rendon, P., Komatsu, J. 2002. Mating and remating of medflies (diptera: tephritidae) in guatemala: individual fly marking in field cages. Florida Entomologist. 85:126-137.

Interpretive Summary: The sterile insect technique is a potent technique to control insect pests in an environmentally safe manner. However, the costs are high and are dependent on the quality of the produced and released sterile flies. One critical aspect of fly quality relates to the mating and remating ability of the sterile flies, esp. the males. Ideally, the sterile flies will be able to mate with virgin females in a competitive manner, and also be able to keep the mated females from remating at higher than normal remating rates compared to wild males. A study of sterile fly mating and remating was conducted in Guatemala in outdoor field cages over a 2-day period using a new technique that individually marked the test flies. Results of the study showed that wild males mated more effectively than lab males for both lab and wild females. Wild males also remated more often than lab males, while wild females remated at the same low (2-8%) rate as lab females. Of major importance was the finding that lab males averaged significantly shorter times in copula than wild males, and females mated first to lab males tended to remate more often. These results are significant for SIT program officials in order to know competitive their released insects are and how to compensate for deficiencies in quality.

Technical Abstract: The sterile insect technique (SIT) depends critically upon the ability of sterilized, released males to locate and mate with wild females. The overall efficiency of the method also depends upon the relative frequencies of remating by wild females following first matings to laboratory or wild males. Using a newly devised technique that individually marks the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), a field cage study was undertaken in a Guatemala coffee orchard to record individual fly mating behaviors between each of several laboratory strain and coffee-reared wild flies. Five laboratory strains were tested a genetic sexing strain examined in sex ratios between 50%-100% sterile males, two standard bisexual strains, and two F1 hybrid strains. The marking technique revealed a substantial amount of information on individual fly mating and remating. Wild male flies significantly outcompeted each of the lab strains in the first matings with both wild and lab females. Approx. 22% and 3% of wild and females, respectively, remated in the field cages during two consecutive morning observation periods, while 4-8% of lab males, and 2-8% of lab females remated, respectively. Male flies from each lab strain averaged significantly shorter copulation times than wild males. Female flies, either lab or wild, tended to remate more often if they first mated to a lab male, but the differences were not statistically significant. An index was devised to provide a measure of relative male mating quality. Wild males tended to have higher individual index values than lab strain males-average values of the latter ranged from ca. half to roughly equal that of wild males.