Studies on the Biology and The Chemical Control of Citrus Leaf Miner Phyllocnistis citrella (Stainton) ((Lepidoptera:Gracillariidae

Abstract

The citrus leaf miner Phyllocnistis citrella Stainton has become one of the most important pests of the citrus in both the nursery and the field in the Sudan. The present work covered some aspects of the biology, ecology and chemical control of the citrus leaf miner P.citrella. The study of the life cycle of this pest on sour orange showed that the mean duration of egg stage was 2.19±0.85 days. The insect passed through four larval instars with mean durations of 1.18±0.02, 1.29±0.04, 2.66±0.03 and 2.19±0.27 days respectively. The pupal stage took 7.35±0.02 days. The main time of adult emergence from the pupae was between 7 a.m and 7 p.m (64.7 %). The sex ratio was 1: 1.3 male: female. The longevity of the adult male and female was 9.81±0.03 and 10.52±0.02 days respectively. The fecundity was 39.73±0.01 eggs and the pre- oviposition period, oviposition period and post- oviposition period were 1.73±0.01, 6.55±0.48 and 2.36±0.08 days respectively. The study also showed that the duration of larval stage was shorter in the lime than in the other tested host species which were sour orange, grapefruit, orange and mandarin. The lime showed highest susceptibility to citrus leaf miner compared to the other tested species. The peaks of the iii population in the field were in October/ November and February - March, while the population of citrus leaf miner in the nursery was high throughout the study period. In the chemical control experiment, Mospilan 20% SL at 0.25ml/L, 0.50 ml/L and 0.75 ml/L were most effective against this pest with residual effect of 14 days compared to Evisect 50% SP at doses 0.75 g/L, 1.0 g/L and 1.25 g/L.