Effect of temperature on the reproduction of Bracon vulgaris Ashmead (Hymenoptera: Braconidae), a parasitoid of the cotton boll weevil

This research studied the effect of temperature on the reproduction of Bracon vulgaris Ashmead, an ectoparasitoid of cotton boll weevil (Anthonomus grandis Boheman) at constant temperatures of 20, 25 and 30(degrees)C, 70 +/- 10% RH and a photophase of 14 h. Females of the parasitoid produced a greater number of eggs when exposed to 25 degrees C (124.65 eggs) in relation to those exposed to 20 (43.40 eggs) and 30 degrees C (49.60 eggs). The number of parasitized larvae per female of B. vulgaris at 25 degrees C (71.75) was greater than at 20 degrees C (31.40) and 30 degrees C (25.15). The daily intrinsic rates of increase (r(m)) were -0.007 at 20 degrees C, 0.07 at 25 degrees C and 0.03 at 30 degrees C, revealing that the temperature of 25 degrees C produced increases of 1,100 and 133% in the value rm in relation to temperatures of 20 and 30 degrees C, respectively. In programs of biological control of the boll weevil using innoculative releases, adult females of B. vulgaris with approximately five (at 25 or 30 degrees C) or 20 day old (at 20 degrees C) should be used; when using innundative releases, adult females of B. vulgaris, with ages between 11 and 31; 9 and 29 or 3 and 14 days, respectively, at 20, 25 or 30 degrees C should be used.