The guava weevil, Conotrachelus psidii Marshall, is a severe pest of guava fruits in Brazil. The mated females lay eggs in small unripe fruits. As the fruits develop, so do the larvae. Mature larvae abandon the ripe fruits and pupate underground. Larval feeding causes extensive damage to the fruit. We conducted this study to understand the weevil biology under laboratory conditions. Weevil-infested ripe guava were collected in orchards and placed inside cages with moist sand. After emergence, the adults were individually placed in acrylic boxes with food and water. Recently emerged adults were also placed inside plastic boxes for mating, after which the females were isolated. The eggs were placed on moist filter paper in petri dishes containing slices of ripe guava fruit. Egg-hatching was monitored daily and the number of larval instars established by measuring the width of their head capsules. The egg incubation period lasted 3.9 ± 0.58 days. The larval period was 16.0 ± 3.80 days and four instars were identified. After burrowing in the soil, the mature larvae (pre-pupa) remained underground for 142.0 ± 32.00 days and then pupated. The pupal period lasted 16.0 ± 0.90 days, but the adults remained underground for a further 34.0 ± 18.00 days. After emerging from the soil, adults lived 148.0 ± 89.00 days. Fecundity varied from 539 to 793 eggs/female, and the percent egg hatch was 96.5%.
Psidium guajava; bionomics; instar
