Author(s): ALVES, T. J. S.; SILVA-TORRES, C. S. A.; WANDERLEY-TEIXEIRA, V.; TEIXEIRA, A. A. C.; TORRES, J. B.; LIMA, T. A.; RAMALHO, F. de S.

Summary: Bracon vulgaris is a larval ectoparasitoid of the boll weevil, Anthonomus grandis, a key cotton pest We investigated the influence of parasitoid age, photoperiod and host availability on B. vulgaris parasitism. Five- and 10-day-old parasitoids were exposed to A. grandis densities of three, six, 12 and 24 larvae per female. Five-day-old females showed higher parasitism rates (F = 21.55, P < 0.0001), with a positive increase in parasitism rate up to 12 larvae, parasitizing an average (±SE) of 1.3 (±0.12), 3.4 (±0.35) and 4.4 (±0.45) larvae (at the densities of 3, 6 and 12 larvae, respectively), dropping to 1.4 (±0.17) when 24 larvae were offered. Next, the period of most parasitism activity during the photophase was determined by exposing five-dayold B. vulgaris females to different durations of light exposure (1, 3, 6, 8 and 10 h) after 12 h darkness. Results showed that the shortest time to host location occurred 8 h after light exposure, when parasitoids were most active searching for the host. A sequence of seven behavioral acts leading to successful parasitism was identified and the transitions between successive behavioral acts were quantified and depicted in an ethogram. The longest duration act was oviposition (or host acceptance), a complex behavior with several distinct phases.

Publication year: 2015

Types of publication: Journal article

Unit: Embrapa Cotton

Keywords: Anthonomus grandis, Bracon vulgaris, Ectoparasitoid, Himenoptero, Parasitism behavior