Dispersão do parasitoide Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae) em cafeeiro irrigado, no semiárido mineiro

Abstract

The aim of this study was to know the dispersion pattern of the parasitoid D. longicaudata during the first five days after its release, on a coffee plantation located in semiarid in northern Minas Gerais. The experiment was carried out on a plantation of 2 ha irrigated and grown in full sun with varieties Catuai Vermelho IAC 99 and IAC 144 and Topázio MG 1190, located in the Jaiba Irrigation Project, MG. About 800 couples of D. longicaudata, aged from 5 to 6 days were released fortnightly from August to November 2011. The parasitoids were released in the center of the area and the evaluations in the four cardinal directions (cast, west, north and south) and the four side (northeast, southeast, northwest and southwest). In each direction the parasitoids were evaluated in 10 points, spaced about 6 m apart, totaling 80 points, distributed throughout the coffee plantation. The dispersion was evaluated by means of "units parasitism" (small bags made from voile fabric containing about 120 larvae of Ceratitis capitata (Wiedemann) in the third instar plus diet), in order to simulate an infested fruit. The units of parasitism were hung in trees and maintained for 24 h in area when then are replaced by new units which remained for 24 h and so on (1, 2, 3, 4 and 5 days after their release). After removal (every 24 h), the units were opened and the larvae put in plastic cups (200 mL) containing vermiculite, used as substrate for pupation and obtaining D. longicaudata adult (descendants) or host (C. capitata). It was determined the mean distance of dispersion (MD) and the dispersion arca (S) of D. longicaudata, during the five days of evaluation, using the model proposed by Dobzhansky and Wright. The MD and S were analyzed in relation to days after release. The mean distance of dispersion and average area of dispersion of the parasitoid were 44.14and 2721.73 m², respectively. The highest MD (59.15) and S (4229.76) were observed in the fifth day after the release. There was a positive correlation between the mean distance and dispersion area of the parasitoid along of days after release. It is possible to affirm that D. longicaudata after being released in the field was able to survive to 5 days under conditions of semiarid, parasitizing an average distance up to 44.14 m.