Diversity, spatial distribution, and sampling for ant management decision‐making in integrated pest management programs in citrus groves

Abstract

AbstractAnts play important ecological roles, such as predation on other arthropods, seed dispersal, and soil structure maintenance. In citrus agroecosystems, ants are considered a secondary pest. The damage they cause is indirect through the disruption of the biological control of pests, especially honeydew producers. In integrated pest management programs, adequate and precise sampling methods are required to accurately determine the need for chemical ant control to minimize the economic and environmental costs of unnecessary chemical treatments and to reduce the risk of crop loss by pests. In Mediterranean citrus groves, eight ant species that differed in abundance and frequency have been found foraging on citrus trees: Lasius grandis Forel, Pheidole pallidula (Nylander), Plagiolepis pygmaea (Latreille), Formica gerardi Bondroit, Formica rufibarbis Fabricius, Camponotus sylvaticus (Olivier), Linepithema humile (Mayr), and Tapinoma erraticum (Latreille) (all Hymenoptera: Formicidae). The trunk was selected as the most efficient sampling unit to establish the monitoring method. Aggregation indices on the trunk of these species were calculated, and enumerative and binomial sampling methods were developed for the most frequent species, L. grandis and Ph. pallidula. Ant species differed in spatial distributions within citrus orchards, and required different sample sizes to estimate population abundance. The minimum sample size required, taking into account the maximum average abundance found – 44.1 L. humile, 17.3 L. grandis, and 3.5 Ph. pallidula per trunk per min –, would be 28, 25, and 54 trees, respectively.