Seasonal monitoring of the flight activity and the incidence of the groundnut leaf minerAproaerema modicella(Lepidoptera: Gelechiidae) at five sites in South Africa

Abstract

The groundnut leaf miner, Aproaerema modicella (Deventer), invaded the African continent in 1998 and is devastating leaf miner pest of groundnut (Arachis hypogaea L.). There is limited information on this pest's ecology to facilitate the management strategies, and thus a study on its ecology was conducted at five sites in South Africa for two years. We monitored A. modicella flight activity using pheromone traps and larval infestation on various commercial (groundnut, soya bean (Glycine maxima L.), lucerne (Medicago sativa L.) and pigeon pea (Cajanus cajan L.)) and wild hosts in order to understand its dispersal and the role of alternative hosts in the carryover of A. modicella populations from one season to another. The data was correlated with site specific climatic data (rainfall, temperature and humidity). At all locations, groundnut leaf miner moths were caught in traps before crop planting. Though low in numbers, groundnut leaf miner moths were caught during winter at all locations other than Brits. Infestations on pigeon pea and lucerne were observed in March and April 2012. A significant negative association between temperature and A. modicella moth catches was observed at Nelspruit, while Vaalharts had a significant positive association between humidity and A. modicella moth catches. There was no significant correlation between any of the recorded environmental factors and moth catches at Manguzi and Brits. Monitoring A. modicella in the current study provided some useful ecological information regarding the pest which assisted in establishing the pest's peak and off-peak periods. This information should be useful in determining control strategies such as pesticide application schedules.