Bioecologia e técnicas de criação de parasitoides (Hymenoptera) nativos de três espécies de Anastrepha no Brasil e no México

Abstract

Fruit flies (Diptera: Tephritidae) are among the main pests of the fruit crops in Brazil. Among the natural enemies, these pests are following the endoparasitoid larva-pupa Doryctobracon brasiliensis (Szépligeti, 1911) (Hymenoptera: Braconidae) having wide geographical distribution in South America and it parasites larvae of different species of fruit flies, in different hosts. These characteristics confer D. brasiliensis potential agent for biological control, mainly of Anastrepha fraterculus (Wiedemann, 1830) (Diptera: Tephritidae), the main species of fruit flies in southern Brazil. For Mexico, the two mains species of fruit flies are Anastrepha ludens (Loew, 1873) (Diptera: Tephritidae) and Anastrepha obliqua (Macquart, 1835) (Diptera: Tephritidae), which are hosts to several species of native parasitoids, especially of families Braconidae [Utetes anastrephae (Viereck 1913), Doryctobracon crawfordi (Viereck, 1911) and Oppius hirtus Fischer, 1963], Eucoilidae [Odontosema anastrephae (Flashing, 1935)], Diapriidae [Coptera haywardi Loiácono, 1981] and Chalcididae (Dirhinus sp.). Thus, the objective of this study was to know the bio-ecology and to develop rearing techniques of native parasitoids of fruit flies. To this end, the following studies were conducted: I) development of a rearing technique of D. brasiliensis in larvae of A. fraterculus; II) biology of D. brasiliensis at different temperatures: fertility life table and thermal requirements; III) rearing parasitoids native to the Americas for biological control of A. obliqua; and IV) Is A. obliqua a natural host of native parasitoids D. crawfordi and O. hirtus? In the first work to develop a rearing technique of D. brasiliensis, it was determined that larvae of the 3 rd instar of A. fraterculus are preferred for parasitism in relation to the 1 st and 2 nd instars. Exposure for 12-h of larvae of A. fraterculus to females of D. brasiliensis provided a larger numbers of parasitoids, higher parasitism rate and a higher rate of females in the offspring population. The number of 25 larvae of A. fraterculus offered to females of D. brasiliensis provided the largest production of parasitoids. The supply of honey at 20% to parasitoids is essential to generate a greater number of offspring with more longevity. In the second work, we observed that females kept at different temperatures produced more parasitoids at temperatures 18-22°C, and the number of offspring per female ranged from 99.4 to 173.8, respectively. Longevity of males and females was inversely proportional to temperature, ranging from 43.9 to 7.4 d for females and from 24.4 to 4.6 d for males, at temperatures 15-30°C, respectively. The duration of the biological cycle (egg-adult) ranged from 41.2 d at 18°C to 20.9 d at 25°C. At temperatures 15, 28 and 30° C, there was no development of immature stages of D. brasiliensis. At 20 and 22° C, we observed the high st values of the net reproduction rate (Ro) and finite reason of increase (λ), which means that at the estimated optimum temperature (21°C), the population of D. brasiliensis increased 47 times each generation. The lower temperature threshold for development or base temperature (Tb) and thermal constant (K) were 10.0°C and 303.2 degree/days. In the third work, we observed that not all parasitoid species studied develop with the same efficiency in larvae of A. obliqua, where U. anastrephae and C. haywardi showed the greatest potential for laboratory rearing. Utetes anastrephae showed better development in young larvae (5-6 d), which provided a greater emergence of adults and, consequently, higher parasitism rate, with higher survival rate. Coptera haywardi presented better development in pupae 1-4 d of age, where they obtained greater emergence and parasitism rates, adults with greater flying skills and greater longevity. In fourth work, we observed that D. crawfordi and O. hirtus prefer to parasitize larvae of A. ludens and that they cannot complete their development in larvae of A. obliqua, although they oviposit in this host. There is encapsulation and melanization of larvae in both parasitoid species. The information obtained in these works contribute to improve knowledge of bio -ecology of the parasitoid species of fruit flies and provide the establishment of rearing techniques for these species.