A report on occurrence of aphidophagous predators of Aphis odinae (van der Goot) (Hemiptera: Aphididae) in cashew ecosystem from Goa, India

Abstract

The aphid, Aphis odinae (Van der Goot) (Hemiptera: Aphididae) is a polyphagous, occasional insect pest of cashew. A field survey was conducted from 2014 to 2015 in cashew plantations to record the incidence of aphid and its predators. Periodical sampling revealed, the occurrence of six species of aphidophagous predators comprising three species of coccinellids, viz., Scymnus castaneus Sicard, Cheilomenes sexmaculata (Fabricius) and Pseudaspidimerus flaviceps (Walker) and three species of syrphids, viz., Paragus serratus (Fabricius), Dideopsis aegrota (Fabricius) and Ischidon scutellaris (Fabricius) were found predating on A. odinae. All the immature stages of predators were found predating on first, second, third and fourth instars of the aphid. Among the coccinellids, the dominant species were S. castaneus (4.26 grubs/nut) followed by C. sexmaculata (0.42 grubs/leaf) and P. flaviceps (0.14 grubs/nut). Of the syrphids, P. serratus 2.39 larvae/nut was the major predator. The species D. aegrota (1.2 larvae/leaf) and I. scutellaris (0.5 larvae/nut) were recorded as minor predators. Seasonal abundance of predators was synchronized with the aphid with a maximum occurrence during February 2015. The aphid population gradually reduced from April onwards due to the voracious feeding activity of the predators. The study concluded that the aphidophagous predators, viz., coccinellids and syrphids play a major role in managing the aphid A. odinae in cashew and could be encouraged for augmentation and conservation of these predators in a cashew based ecosystem.