Submitted to: Journal of Entomological Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/16/2011
Publication Date: 1/20/2012
Citation: Thomas, D.B. 2012. Mexican fruit fly (Diptera: Tephritidae) and the phenology of its native host plant, Yellow Chapote (Rutaceae) in Mexico. Journal of Entomological Science. 47:1-16. Interpretive Summary: The Mexican fruit fly is a major pest of citrus in Mexico and the border areas of the USA. In its native habitat, the fly breeds on a wild plant called yellow chapote, which is a citrus relative. In the mountains of northeastern Mexico, this tree produces fruit in the springtime and these fruit are infested with fly maggots. The life cycle of the fly population was studied on the wild host plant in order to observe the insect in the habitat which it is naturally adapted to and in populations that are unaffected by control strategies, such as the application of insecticides. The peaks in the fly population tracked the production of fruit by the chapote trees. Temperatures and rainfall determined the flowering and fruiting of the trees. Under favorable conditions, the fruiting season was prolonged and this allowed for an extra generation of flies. Importantly, mature female flies were attracted to the chapote trees when they began producing fruit and these females were the parents of the succeeding generation. If one extrapolates from the natural situation to the commercial, one can expect two peaks in the fly population: the first a small peak consisting of mature females and the second a large peak consisting of immature males and females. The latter peak could be targeted with the sterile insect technique. However, the former would not be susceptible to that method and would require a more traditional toxic-bait treatment. The application should be time to the maturity and susceptibility of the fruit, rather than to trapping surveys.
Technical Abstract: In northeastern Mexico, the Mexican fruit fly, Anastrepha ludens (Loew), breeds on its native host, yellow chapote, Casimiroa greggii (Wats.), which typically produces fruit in the spring. Peak populations of the fly occur in late spring or early summer when adults emerge from the generation of larva which developed in the spring crop. The parents of the spring generation are flies attracted into the groves of yellow chapote by the presence of fruit. Thus, the reproductive phenology of the fly population depends on the reproductive phenology of the host plant. The reproductive phenology of the host plant tracks ambient conditions, in particular, the timing and quantity of rainfall during the pre-flowering and fruiting season. A prolonged fruiting period can result in production of two successive generations of the fruit fly. Infestation rate of the fruit is inversely proportional to the size of the crop; a predictable outcome of the synchronized mass fruition paradigm (environmental saturation) as a strategy to escape or limit depredation. A strategy to protect a fruit crop might be more effective by targeting the early ovipositing females rather than the succeeding larger peaks of adults.