THE DISTRIBUTIONS OF PARASITOIDS (HYMENOPTERA) OF ANASTREPHA FRUIT FLIES (DIPTERA: TEPHRITIDAE) ALONG AN ALTITUDINAL GRADIENT IN VERACRUZ, MEXICO

Authors: Sivinski, John; ALUJA, MARTIN - INST DE ECOL, XALAPA MEX; PINERO, JAIME - INST DE ECOL XALAPA MEX

Submitted to: Biological Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary: Fruit flies infest dozens of species of fruits in tropical America and are responsible for the erection of quarantines that hinder agricultural development. Biological control, through the conversation and /or augmentation of native parasitoids, is one means of suppressing pest populations. In addition, these parasitoids might be introduced into Florida and elsewhere to attack fruit flies such as the Caribbean fruit fly, Anastrepha suspensa, that have few native natural enemies of their own. In southern Mexico, 10 species of parasitoids develop in Anastrepha species of fruit flies. In order to predict where and when each could be best introduced or mass-released, scientists at Center for Medical, Agricultural and Veterinary Entomology, USDA, ARS and at the Institute of Ecology in Veracruz, Mexico, determine the environmental factors of that influence their distributions. Altitude effects the abundances of many species; some are more common at high altitudes and other at low. These patterns of distribution are complex and appear to be the result of different tolerances for warm and dry weather, the environmental preferences of competing species, and the distributions of various fruit fly-host plants. However, several patterns in species that are candidates for augmentative release might be of immediate agricultural significance since they clearly identify appropriate habitats.

Technical Abstract: In southern Veracruz state, Mexico, fruits from 38 sites at various altitudes were collected monthly over 2 years, and the Anastrepha spp. fruit flies and associated parasitoids that emerged from these fruits were identified and counted. Of the 26 species of fruits that contained Anastrepha larvae, 18 species also contained a total of 10 species of Anastrepha parasitoids. These consisted of 4 native and 1 exotic species of opiine braconid larval-pupal parasitoids, 2 species of eucoilid larval-pupal parasitoids, 1 exotic species of eulophid larval-pupal parasitoid, 1 exotic pteromalid pupal parasitoid and 1 native diapriid pupal parasitoid. Overall parasitism was 6% and was greatest, 16%, at 600-800m. The contributions of individual parasitoid species to overall parasitism were influenced by both altitude and the species of plant in which the Anastrepha larvae were found. This was particularly the case among the more abundant and wide-spread Braconidae. To distinguish the role of altitude from that of the distributions of the host plants, these braconids were examined in 4 species of fruit that grew over a broad range of altitudes. In guava and "jobo" the parasitoid, Doryctobracon areolatus, was relatively more common at low altitudes. Its congener, D. crawfordi, was relatively abundant at high altitudes in sour orange. Utetes anastrephae became relatively more common at higher altitudes in S. mombin, whereas D. longicaudata tended to become relatively rare at the highest altitudes in C. aurantium, but increased at high altitudes in P. guajava compared to other braconids. Different altitudinal patterns of abundance in different fruits with distinct suites of competitors suggests the importance of both biotic and abiotic factors in parasitoid distributions.