ABSTRACT
The mealybug Planococcus ficus (Signoret) (Hemiptera: Pseudococcidae) has recently been detected in vineyards in southern Brazil. The ant Linepithema micans (Forel) (Hymenoptera: Formicidae) is the most abundant and frequent species in these vineyards, acting mainly as a disperser of the native soil scale, the ground pearl Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae). This study evaluated the interactions (dispersal and predation) of L. micans with P. ficus. The first experiment evaluated the interaction between L. micans and P. ficus in a greenhouse, using Paulsen 1103 rootstock (Vitis berlandieri × Vitis rupestris) planted in pots. Plants were infested by 1) adult females of P. ficus, and 2) adult females of P. ficus and L. micans, and all mealybugs remaining after the experimental period were counted. To evaluate P. ficus predation by L. micans, two laboratory experiments were conducted (25°C, 80% relative humidity). In the first experiment, sprouted potatoes were infested with ovisacs, first-instar nymphs and adult females of P. ficus and evaluated in three treatments: 1) L. micans fed with carbohydrate and protein, 2) L. micans without food, and 3) without ants present. In the second, potatoes were infested only with first-instar nymphs of P. ficus and were exposed in two treatments: 1) L. micans without food, and 2) without ants present. The results were evaluated by counting the remaining mealybugs, with and without ants. The results showed that L. micans does not transport P. ficus, and predates on first-instar nymphs of the mealybug.
Subject(s)
Animal Distribution , Ants , Hemiptera , Predatory Behavior , Animals , Female , VitisABSTRACT
Linepithema micans (Forel) (Hymenoptera: Formicidae) is the main ant species responsible for dispersal of Eurhizococcus brasiliensis (Wille) (Hemiptera: Margarodidae), a root scale that damages grapevines in southern Brazil. The effects of different formulations of toxic baits based on boric acid and hydramethylnon to control L. micans and E. brasiliensis were evaluated. Toxic baits with boric acid (1.0%) mixed in different concentrations of inverted sugar (20%, 30%, and 40%), and hydramethylnon, mixed with sardines (paste), cassava flour and peanut, brown sugar (sucrose), or sardine oil-based gel, were evaluated in a greenhouse and in the field. In the greenhouse experiment, the number of foraging ants was significantly reduced in the pots where the hydramethylnon in sardine paste (Solid S), sardine oil-brown sugar-based gel (GEL SAM), and peanut oil-brown-sugar gel (GEL AM) formulations were applied. The GEL SAM toxic bait effectively reduced the infestation of L. micans, and could be used for indirect control of E. brasiliensis on young grapevines.
