Temperature-based phenology model of African citrus triozid (Trioza erytreae Del Guercio): Vector of citrus greening disease

Abstract

The African citrus triozid (ACT), Trioza erytreae Del Guercio (Hemiptera: Triozidae), is the major vector of the ‘Candidatus Liberibacter africanus’, associated with the African citrus greening disease [huanglongbing (HLB)]. Although T. er y treae is a very destructive pest in citrus production with yield losses up to 100%, there is limited information on its thermal biology, which is a prerequisite for developing an envi-ronmentally friendly management strategy. This study investigated the effect of temperature on the development and survival of T. er y treae under eight constant temperatures (10, 15, 18, 20, 22, 24, 27 and 30°C), relative humidity of 65 ± 5% and a photoperiod of 12D:12L. Using Insect Life Cycle Modeling software, we fitted linear and non- linear models to T. er y treae development and mortality data. The best-fitted functions were compiled for each life stage to yield a phenology model. Our find-ings revealed that temperature had a significant effect on the development of all the immature stages. No complete development was observed at 10, 27 and 30°C. The developmental time of eggs ranged from 5.27 days at 24°C to 13.5 days at 15°C. The lowest developmental temperature threshold ranged between 3 and 15°C, with ther-mal constants ranging between 16.7 and 100 degree-days. The 1st nymphal instars recorded the highest mortality at 15°C. The highest survival rates of the 3rd instar nymphs were recorded at 20°C. The model predicted that temperatures between 20 and 25°C were optimal for the survival of all the immature life stages, except for the 1st nymphal instars. Our results provide relevant information on the impact of temperature on the development and survival of T. er y treae, which is essential for the development of more efficient management strategies