The Effect of Temperature on Development and Fecundity of Citrus Leafminer, Phyllocnistis citrella

Abstract

Citrus leafminer, Phyllocnistis citrella (Lepidoptera: Gracillaridae), recently has become a serious pest in Syria, especially in citrus nurseries. Development and fecundity of P. citrella were recorded at four constant temperatures ranging from 20, 25, 30, 35±1°C, 70±10% relative humidity and photoperiod of 14:10 hours (L:D) and on seedlings of Citrus sinensis cultivar Valencia as host. This study was carried out in the laboratories of Latakia Center for Breeding and Applications of Biological Enemies during 2022. Results obtained indicated that the developmental time (egg to adult) of P. citrella decreased with increasing temperatures, ranging from 20.82 days at 20°C to 10.25 days at 35°C. Results also showed significant reduction in the incubation period from 7.58 days at 20°C to 2.66 days at 35°C, and mortality rate increase from 13 to 22% at 20 and 35°C. respectively. The larval period was 9.44, 5.24, 4.48 and 4.0 days and pupal period was 9.22, 6.84, 5.76 and 4.78 days at 20, 25, 30 and 35°C, respectively. The highest mortality rate in egg, larval and pupal periods was observed at 35°C (22.00, 11.50 and 15.94%, respectively). At all temperatures studied the females lived significantly longer than the males. Both females and the males lived longer at a temperature of 20°C (the female 13.3 and the male 11.5 days) and shorter at 35°C (5.8 days for females and 4.5 days for males). The study showed that the preoviposition period was very short. Results showed significant reduction in Oviposition period, ranging from 8.43 to 5.52 days at 20 and 35°C, respectively. The fecundity was found to be 27.74, 46.413, 57.8 and 49.5 eggs/female at 20, 25, 30 and 35°C, respectively. The sex ratio for the offspring was 1:1.2, 1:1.4, 1.0: 1.5 and 1:1 male: female at 20, 25, 30 and 35°C, respectively. It can be concluded from this study that the temperature of 30°C was optimal for P. citrella development.

Keywords:

Citrus leaf miner, Phyllocnistis citrella, development, fecundity, sex ratio.