USE OF REPELLENTS IN Cotesia flavipes (Cam.) (Hymenoptera: Braconidae) PUPAE FOR AERIAL RELEASE

Abstract

The aerial release of Cotesia flavipes for the control of Diatraea saccharalis (F.) (Lepidoptera: Crambidae) in sugarcane is a reality that replaces the archaic and costly manual release, a strategy that will facilitate the biological control of the sugarcane borer. However, the pupal scattering of the parasitoid on the soil and plants could be compromised by predation. The use of repellents is a viable option and trichloroisocyanuric acid is effective in the repellency of predators in the field. Therefore, the objective of this work was to evaluate the effect of trichloroisocyanuric acid on the emergence and sexual ratio of C. flavipes in the laboratory and an evaluation of the repellency of predators in the field for this substance. In a completely randomized design, the following substances and amounts mixed with C. flavipes "masses" (set of pupae containing cocoons wrapped in silk threads) were tested: trichloroisocyanuric acid powder (55%), liquid trichloroisocyanuric acid (3.3%) plus odorless talc, trichloroisocyanuric acid (55%) plus odorless talc and with only odorless talc (Control). Each treatment was repeated 10 times, each repetition being a "mass" placed in a flat bottom glass tube, closed with plastic film, all of which were kept in an air-conditioned room at 27 ± 1 ° C, RH of 70 ± 10% and photophase of 14 H. The treatments were also repeated 10 times in the field. Each "mass" was placed in line at a distance of one meter, simulating an aerial release of 6,000 ha-1 parasitoids. After 12, 24 and 48 h of release, the masses were evaluated for predation. There were no significant differences between the treatments in the mean percentage of emergence and mean sexual ratio, which were respectively 61.25 ± 8.11% and 0.74 ± 0.06. After 12 h of field release, the control treatment already had all the "masses" predated, whereas the treatment treated with trichloroisocyanuric acid powder did not show predation until 48 h after field release. These results indicate that trichloroisocyanuric acid, whether or not mixed with talc (for the individualization of "masses"), can be used with the parasitoid in C. flavipes aerial release equipment with a satisfactory effect on the repellency of predators.