Lek Behavior of Mediterranean Fruit Flies: An Experimental Analysis

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), is a ubiquitous pest of fruit trees, causing significant economic damage both in the U.S. and in Israel. Control efforts in the future will rely heavily on the sterile insect technique (SIT). Success of such operations hinges on the competitive ability of released males. The mating system of the medfly is based on leks. These are aggregations of sexually signaling males that attract females (who then select and copulate a courting male). A major component of male competitiveness is their ability to join existing leks or establish leks that are attractive to wild females. Accordingly, we identified leks and the behaviors associated with them as critical for the success of SIT operations. The objectives of this proposal were to determine 1. what makes a good lek site, 2. what are the energetic costs of lekking, 3. how females choose leks, and finally 4. whether the copulatory success of sterile males may be manipulated by particular pre-release diets and judicious spatial dispersal. We established that males choose lek sites according to their spatial location and penological status, that they avoid predators, and within the lek tree choose the perch that affords a compromise between optimal signalling, micro-climatic conditions and predation risk (Kaspi & Yuval 1999 a&b; Field et al 2000; Kaspi & Yuval submitted). We were able to show that leks are exclusive, and that only males with adequate protein and carbohydrate reserves can participate (Yuval et al 1998; Kaspi et al 2000; Shelly et al 2000). We determined that females prefer leks formed by protein fed, sexually experienced males (Shelly 2000). Finally, we demonstrated that adding protein to the diet of sterile males significantly enhances their probability of participating in leks and copulating wild females (Kaspi & Yuval 2000).

Insect territoriality

Territorial behavior has been reported in many orders of insects, particularly among the Odonata, Orthoptera, Hemiptera, Coleoptera, Hymenoptera, Lepidoptera, and Diptera. Although territoriality has been recognized among immature stages as well as in both sexes of adult insects, most of the published reports deal with the reproductive consequences of aggressive interactions among territorial males. Some dominance hierarchies have been described, particularly among cockroaches and megachilid and halictid bees. Lek behavior has also been reported among dragonflies, butterflies, and Hawaiian drosophilids. In all the species studied, territorial behavior spreads males through a habitat, minimizing intruder interference with courtship and mating, and increasing the probability that females will be mated. Besides these intraspecific effects, however, aggressive behavior towards unrelated species may reverberate through the larger community. For example, repeated attacks by aggressive files may cause pollinating bees and aphidophagous predators to change their foraging routes, and thus prevent them from servicing particular habitats.