Influence of Temperature Variability on Survival and Development of Citrus Leaf Miner, Phyllocnistis citrella Stainton (Lepidoptera: Gracilariidae) in Tanzania

Abstract

Due to limited information on Phyllocnistis citrella’s Biology, study was aimed to examine the effects of different temperature levels on biology of citrus leaf miner under controlled laboratory conditions at the Entomology laboratory of Sokoine University of Agriculture (SUA), Tanzania from December 2011 to September 2012. Leaf samples (1,985 leaf samples) considered to contain larvae in serpentine mines were collected and individually incubated at room temperature. The emerging adults were wet preserved in 70% ethanol while some dry preserved using special micro pins under microscope for future identification. A Monterey LG8920 pheromone trap was set in every 10m2 at SUA citrus orchard to trap adult moths to supplement sample sources. Citrus leaf miners species collected were identified and four different temperature levels (20, 25, 30 and 35°C) were monitored at each developmental stage. Results revealed longer development time (egg to adult) at 200C and shorter at 300C in 28 and 10 days while the total mortality was 26.67% at 200C and 6.67% at 300C respectively. Oviposition period and rate were negatively and positively influenced by temperature (from 9.26 days at 200C to 6.21 days at 300C and 15.2 eggs/ female/ day at 300C and 6.8 eggs/ female/ day at 200C respectively). The overall fecundity was 28.2 eggs/ female at 200C and 57.1 eggs/ female at 300C. High larval mortality rate was recorded compared to the egg stage while no mortality observed at pupa stage. Conclusively, the pest on this temperature range (200C, minimum to 300C, maximum) has high fecundity, low mortality rate and the developmental time was positively correlated with high temperature, therefore considered optimum temperature range for its survival and development. Other researches especially Integrated Pest management are imperative for sound management package as per the pest in Tanzania and beyond.