POTENTIAL FOR ORGANIC MANGO PRODUCTION IN THE NORTHERN TERRITORY OF AUSTRALIA USING WEAVER ANTS, OECOPHYLLA SMARAGDINA, (HYMENOPTERA: FORMICIDAE)

Abstract

High demand of organic mango in domestic and overseas markets has been increasing since the 1990s. However, insect pests are one of the main constraints limiting organic mango production in the Northern Territory. Previous work showed that weaver ants are effective in controlling the major mango insect pests, but they have not been extensively used because of three issues of concern by mango growers: (1) the ants may reduce mango yield due to their aggressive behaviour towards pollinators; (2) the ants farm mealy bugs that, in turn, may affect fruit quality; and (3) the ants annoy farm workers at harvest. Field experiments, together with long-term monitoring programs, were conducted in four non-spray or organic mango orchards from 2001 to 2003 in the Darwin area of Australia to address these issues. Data obtained from the four sites showed that compared with the treatment without weaver ants, the treatment with abundant weaver ants produced either similar or more fruit/tree/year, and 20.3%/tree/year more first class fruit. The overall profit /tree/year in the treatment with abundant weaver ants was 55.5% higher than the treatment without the ants. Putting fruit picked with a long-handled picking pole directly into a bucket filled with water and mango wash seems to be a useful way to avoid ant disturbance.