Effects of Temperature, Photoperiod, and Rainfall on Morphometric Variation of Diaphorina citri (Hemiptera: Liviidae)

Phenotypic plasticity provides a mechanism by which an organism can adapt to new or changing environments. Earlier studies have demonstrated the variability of Diaphorina citri Kuwayama (Asian citrus psyllid) population dynamics, but no analysis of morphological changes induced by seasonal or artificial laboratory-induced conditions has yet been documented. Such morphometric variation has been found to correspond in dispersal capabilities in several insect taxa. In this study, the effects of temperature and photoperiod on morphometric variation of D. citri were examined through laboratory rearing of psyllids under controlled temperatures (20 °C, 28 °C, and 30 °C) and under a short photoperiod of 10.5:13.5 (L:D) h and a long photoperiod of 16:8 (L:D) h. Diaphorina citri were field-collected monthly from three citrus groves in Fort Pierce, Gainesville, and Immokalee, FL, to evaluate potential field-associated environmental effects. Both traditional and geometric morphometric data were used to analyze the correlation between environmental and morphometric variation. A strong correlation was found between temperature and shape change, with larger and broader wings at colder temperatures in the laboratory. Short day length resulted in shorter and narrower wings as well. From the field, temperature, rainfall, and photoperiod were moderately associated with shape parameters. Adult D. citri with blue/green abdomens collected in the laboratory and field studies were larger in size and shape than those with brown/gray abdomens.