Sampling methods for estimating ants’ abundance on citrus trees

Abstract: Ants are considered a secondary pest in citrus. The damage they cause is indirect, through the biological control disruption of pests, especially honeydew producers. Furthermore, ants play other important ecological role such as predation of other arthropods, seed dispersal and soil structure maintenance. In IPM Programs, adequate and precise sampling methods would enable growers to more accurately determine when to perform chemical ant control, therefore saving costs on unnecessary chemical treatments and reducing risk of crop loss by pests. Ants access the citrus tree canopies mainly through the trunk for searching honeydew producers. In 26 citrus commercial groves located in Northeast Spain, the ant species composition and abundance in trunk were assessed in 100 samplings during 2011 and 2012. Eight ant species were found, differing in abundance and frequency: Lasius grandis, Pheidole pallidula, Plagiolepis pygmaea, Formica gerardi, F. rufibarbis, Camponotus sylvaticus, Linepithema humile and Tapinoma erraticum. Aggregation indices on the trunk of these species were calculated using Taylor’s power law. Enumerative and binomial sampling plans for the most abundant and frequent species in citrus, L. grandis and Ph. pallidula, were developed.