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. erytreae 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 environmentally friendly management strategy. This study investigated the effect of temperature on the development and survival of T. erytreae 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. erytreae development and mortality data. The best‐fitted functions were compiled for each life stage to yield a phenology model. Our findings 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 thermal 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. erytreae, which is essential for the development of more efficient management strategies.

Ecological models predict narrow potential distribution for Trioza erytreae, vector of the citrus greening disease

“…Indeed, the Maxent models identified a negative effect of high temperatures on the probability of African citrus psyllid occurrence, which is consistent with early field observations (Moran VC & Blowers 1967;Green and Catling 1971;Samways 1987) and recent laboratory-derived evidence that this species is heat-sensitive (Aidoo et al 2022). Similarly, models have identified a negative correlation between low winter temperatures and the likelihood of African citrus psyllid occurrence, consistent with the apparent lack of cold-induced diapause in this psyllid and the long-standing assertion that a temperature of 10 degrees Celsius is the lower threshold for development of various life stages of this species (Catling 1969(Catling , 1973.…”

“…Similarly, models have identified a negative correlation between low winter temperatures and the likelihood of African citrus psyllid occurrence, consistent with the apparent lack of cold-induced diapause in this psyllid and the long-standing assertion that a temperature of 10 degrees Celsius is the lower threshold for development of various life stages of this species (Catling 1969(Catling , 1973. Similarly, no complete development of T. erytreae was observed in climatic chambers kept constantly at 10 degrees Celsius (Aidoo et al 2022). Bioclimatic models also suggest that high amounts of was not certified by peer review) is the author/funder.…”

Risk-based regionalization approach for area-wide management of HLB vectors in the Mediterranean Basin

“…According to Aidoo et al. (2022) , a “favorable day” for AfCP ( FD afcp ) was defined considering that it is able to develop at mean temperatures ( T mean ) between 10°C, as T l , and 27°C, as T u and also including a saturation deficit ( SD ) ≤ 32.1 mmHg ( Catling, 1969 ; Catling, 1972 ).…”

“…For ACP, T l = 10.45°C and DD = 249.88°C were the values selected according to Liu and Tsai (2000). For AfCP, T l = 10°C and DD = 270.00°C based on the work of Catling (1973) and Aidoo et al (2022).…”

“…According to Aidoo et al (2022), a "favorable day" for AfCP (FD afcp ) was defined considering that it is able to develop at mean temperatures (T mean ) between 10°C, as T l , and 27°C, as T u and also including a saturation deficit (SD) ≤ 32.1 mmHg (Catling, 1969;Catling, 1972). This insect species is particularly sensitive to the effects of high temperature and low relative humidity, which are combined in the SD index.…”