Efficacy of neem oil against thrips (Thysanoptera) on mango panicles and its compatibility with mango pollinators

Abstract

A field trial was conducted in a mango (Mangifera indica L.) orchard located on Penang Island, Malaysia, to determine the efficacy of neem oil at 1, 2 and 3% concentrations and imidacloprid, a commonly used synthetic insecticide, on populations of thrips and their toxicities to mango pollinators. Daily periodicities of several pollinators that frequently visited mango panicles were studied prior to the insecticide trial to determine the appropriate time of insecticide application. Pollinators were collected at 2-h intervals for 2 months in the dry season and 1 month in the wet season of 2009. Mean numbers of all pollinators were greater in the morning (0800 h) and peaked in the late afternoon, but remained low during other times of the day. After two consecutive applications at 7-day interval, both neem oil and imidacloprid effectively reduced thrips populations compared to an untreated plot. Imidacloprid was the most effective insecticide reducing 68.7% thrips adult and 80.7% larval populations, respectively. However, it caused 92.5% mortality in pollinator populations. Neem oil at 2% was effective against adult thrips 96 h after the second application (59.8% reduction) and caused only 24.9% mortality of pollinators. Proper timing of neem oil application such as at midday when pollinators are least active would control thrips populations satisfactorily but less detrimental to mango pollinators. Future improvement of neem oil formulation should be aimed at improving its efficacy against thrips and further reducing toxicity to pollinators.