Interactions between ants and mealybugs in sugarcane: species and effects on insect pests

The objective of this work was to evaluate ant species interacting with mealybugs in sugarcane plantations, the frequency of occurrence, and the effects of the interaction with ants on mealybug population size. The data was collected in a sugarcane plantation area in Seropedica, Rio de Janeiro, Brazil. The insect species were collected from 70 thoroughly inspected sugarcane plants and the nature and frequency of the interactions were evaluated. The effect of the interaction with ants on mealybug abundance was evaluated by counting the number of adult females of each mealybug species on ten plants isolated and ten plants not isolated from ants. Two mealybug species were collected: Aclerda takahashii (Kuwana, 1932) and Saccharicoccus sacchari (Cockerell, 1895). Ten and seven ant species were found interacting with A. takahashii and S. sacchari, respectively, which were distributed among six genera; the most frequent genera were Crematogaster and Camponotus. Three ant species interacted exclusively with A. takahashii, whereas the others interacted with both mealybug species. The abundance of A. takahashii females was significantly higher on non-isolated than on isolated plants (Paired t-test; t = 2.34; p = 0.04). However, no significant difference in S. sacchari abundance was found between isolated and non-isolated plants (t = 0.27; p = 0.8), nor for the two species combined (t = 1.9; p = 0.09). Thus, ant species that interact with mealybugs in sugarcane plantations cause increases in A. takahashii populations which, at a larger scale, can reduce crop yield.