Life history of Triaspis eugenii Wharton and Lopez-Martinez (Hymenoptera: Braconidae) and evaluation of its potential for biological control of pepper weevil Anthonomus eugenii Cano (Coleoptera: Curculionidae)

The pepper weevil, Anthonomus eugenii Cano, is considered the most important pest of peppers (Capsicum spp.) in Tropical and Subtropical America. Juvenile stages develop inside buds and immature fruits, so that only adults are susceptible to insecticidal control. No viable biological tactic has been developed to combat this pest but Triaspis eugenii, a braconid recently collected in Mexico that attacks pepper weevil eggs, could offer an important addition to its management. The parasitoid was collected from Nayarit, Mexico, during 2003, and a rearing methodology was developed using pepper weevil reared on immature 'Jalapeno' peppers. Low levels of parasitism and high levels of superparasitism hampered the rearing and reliable estimation of parasitoid demography until the weevil rearing system was improved. Confining individual mated females to a single immature 'Jalapeno' fruit maximized weevil fecundity, and also the number of oviposition punctures that were plugged by female. Weevils fed with pepper floral buds, a high nitrogen source, and immature 'Jalapenos' laid 5.5 eggs per female per day over a life span of 64.5 d at 27 +/- 2°C. The net reproductive rate (Ro=158.1) and intrinsic rate of increase (rm=0.14) obtained in a life table study were higher than any previous report.; T. eugenii is a solitary egg-prepupal parasitoid of the pepper weevil. At 27 +/- 1°C, T. eugenii eggs hatched at 23 +/- 1 h. Females developed in 16.6 +/- 0.9 d and males in 16.4 +/- 0.9 d. Females (n=10) laid 402 +/- 199 eggs of which less than 50% reached the adult stage because of high levels of superparasitism in the laboratory. Ovipositing females lived 16.5 +/- 3.02 d, and parasitoids died in fewer than 48 h without carbohydrates (honey). Net reproductive rate (Ro) was estimated at 106 and 167, and intrinsic rate of increase (r m) at 0.24 and 0.26 with and without superparasitism respectively.; The oviposition plug deposited by the pepper weevil played a decisive role in the ability of T. eugenii to find and to parasitize weevil eggs. Crowded rearing conditions inhibited deposition of oviposition plugs and consequently efficiency of parasitism. Wasps were able to find hosts in field cages, and semiochemicals from weevil-damaged plants appeared to play a role in host patch location. However, T. eugenii did not stay more than 120 min in the patch regardless of the presence of weevil damaged plants. Superparasitism was less frequent in the field cages (28%) compared to the laboratory (55-64%). The relatively short duration of foraging on large patch size compared to the rearing environment might explain why.; T. eugenii was recovered in low numbers from field releases in spring 2005 at Immokalee, FL, and at least one generation was completed in the field. No wasps have been recovered after that although sampling has been limited. Even if T. eugenii does not establish in Florida, its host specificity, its ability to parasitize weevil eggs, and its almost double intrinsic rate of increase, compared to the pest, make this parasitoid an excellent prospect for biological control by augmentation against the pepper weevil.