The distributions of parasitoids (Hymenoptera) of Anastrepha fruit flies (Diptera : Tephritidae) along an altitudinal gradient in Veracruz, Mexico

In the state of Veracruz, Mexico, fruits from 38 sites at various altitudes were collected monthly over a period of 2 gears, and the tephritid fruit f lies of the genus Anastrepha and associated parasitoids that emerged from t hese fruits were identified and counted. Of the 26 species of fruits that c ontained Anastrepha larvae, 18 species also contained a total of 10 species of Anastrepha parasitoids. These consisted of 4 native and 1 exotic specie s of opiine braconid larval-pupal parasitoids, 2 native species of eucoilid larval-pupal parasitoids, 1 exotic species of eulophid larval-pupal parasi told, 1 exotic species of pteromalid pupal parasitoid, and I native species of diapriid pupal parasitoid, Overall parasitism (including flies from fru it species that bore no parasitoids) was 6% and was greatest, 16%, at 600-8 00 m in altitude. The relative contributions of individual parasitoid speci es to overall parasitism were frequently influenced by both the altitude la nd correlated changes in temperature and precipitation) and the species of plant in which the Anastrepha larvae were found. This was particularly the case among the more abundant and widespread Braconidae. To distinguish the role of altitude from that of the distributions of the host plants, these b raconids were examined in 4 individual species of fruit that grew over a br oad range of altitudes. In guava (Psidium guajava L.) and "jobo" (Spondias mombin L,) the parasitoid Doryctobracon areolatus (Szepligeti) was relative ly more common at low altitudes. Its congener, Doryctobracon crawfordi (Vie reck), was relatively more abundant at high altitudes in sour orange (Citru s aurantium L.. Utetes anastrephae (Viereck) became relatively more common at higher altitudes in S. mombin, whereas Diachasmimorpha longicaudata (Ash mead) tended to become relatively rare at the highest altitudes in C. auran tium, but increased at high altitudes in P. guajava compared to other braco nids. Different altitudinal patterns of abundance in different fruits sugge sts the importance of both biotic and abiotic factors in parasitoid distrib utions. We discuss the effect of an expanding agricultural frontier on para sitoid abundance and relate our findings to the design of a fruit fly biolo gical control program that tailors mass releases to parasitoid climate pref erences.