Effect of orange peel substances on mating competitiveness of male Ceratitis capitata

The response of wild Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) males to orange peel chemicals and their effect in mating competitiveness o f males exposed to these chemicals was studied in the laboratory (25 +/- 2 degreesC, 65 +/- 5%, r.h.). Males were attracted, landed, and arrested on r ipe oranges that were superficially wounded in the flavedo region of the pe el, and fed on the wounds. Exposure to wounded oranges conferred to males a mating advantage over unexposed males. In flies of 1 to 10 days of age, th is advantage was independent of the age of the flies during exposure and la sted at least 10 days following exposure. Twenty-four hours of exposure ens ured this effect. Exposure to intact oranges, or to wounded oranges covered with a wire-screen, which allowed olfactory response and landing on the sc reen but not direct contact with the fruit, did not confer any mating advan tage. Apparently, males required direct contact with wounded oranges in ord er to increase their mating competitiveness. It is suggested that the acqui sition of certain substances of the flavedo, most probably through their in gestion, is responsible for the observed phenomenon. Our findings are discu ssed in relation to the sexual behaviour of this fly. Implications of these findings for the enhancement of the mating competitiveness of released ste rile males and of the effectiveness of the Sterile Insect Technique program s are discussed as well.