Predatory Ants of Diaprepes abbreviatus (Coleoptera: Curculionidae) in Citrus Groves in Martinique and Guadeloupe, F.W.I.

Abstract

Although ants were used as biocontrol agents by different ancient cultures, few works on the possible use of ants as natural enemies of agricultural pests are known. The role of ants in protecting forests against hervibores in the northern hemisphere is well documented (Pavan 1961, Gosswald et al. 1968). Several studies, evaluating ants as possible predators of pests, have been carried out on cocoa plantations in Africa (Leston 1972, 1973, Majer 1972, Room 1971) and in South America (Jaffe et al. 1987). Also, ants may interfere with control agents for tuliptree aphids (Dreistadt et al. 1986). Tryon (1986) and Fowler (1988) showed that ants have an untrapped potential in biological control, including citrus grove pests. Among the 23 species of 5 genera of Curculionidae known to attack citrus in Martinique and Guadeloupe, Diaprepes abbreviatus (L.), D. famelicus (Oliver), D. marginatus (Fabrcius) and Litostylus pudens (Boheman) are common pests since 1973, though D. marginatus is absent in Martinique (Mauleon & Marival 1986). Although it is not the primary problem affecting production, they remain an important insect pest on citrus. Whitcomb et al. (1982) reported two Pheidole species, Tetramorium similluni and Paratrechina bournonica as possible control agents for D. abbreviatus in Florida, though different live stages of these curculionids may be affected by various predators (Whitcomb et al. 1982, Mauleon & Marival 1986, Tryon 1986). Diaprepes spp deposit their eggs between leaves that are glued together with a genital secretion. Once the larvae emerge, they drop to the ground and penetrate into the soil where they spend all their larval stages. The insect pupates in the soil. Life stages that might be succeptible to ant predation are, the eggs, first instar (before burying), and recently emerged adults. To evaluate the possibility of using ants for biological control of Diaprepes pests in the French Antilles, a search was made for the most promissing autoctonous ant species. Ant species in citrus groves were collected from October 1986 to April 1987 on trees and on the ground, during a minimum of 4 h at each site following the hand collecting method described elsewhere (Romero & Jaffe 1989). Collections were made only during the day. Sites visited were: Guadeloupe: Vieux-Habitants (1), Capesterre (2) and Duportail (3); and Martinique: Riviere Lezarde-Saint Joseph (1), Habitation Moulin a Eau-Le Robert (2), Hab. Belle Vue-Marigot (3), Hab. Concorde-Sainte Marie (4), Hab. Grand Case-Le Precheur (5) and Morne Rouge (6). In Table 1, only species that were collected in more than two trees at each location were reported. Groups of at least 10 eggs, first or last D. abbreviatus instars or 1 adult were offered to workers of at least 3 different colonies on the ground around citrus trees, in Riviere Lezarde, Martinique, in Vieux Habitantes and in Capesterre, Guadeloupe. Ant species collecting all eggs or larvae 10 min after a scout ant discovered the food, or attacking