Abstract:
The African citrus triozid (ACT), Trioza erytreae Del Guercio, is a destructive pest
particularly on citrus, and vectors, “Candidatus” Liberibacter africanus (CLaf), which is
the causal agent of the African citrus greening disease. Our study seeks to establish
the distribution and host‐plant relationship of ACT across citrus production areas in
Kenya. We also modelled the risk of spread using the maximum entropy modelling
algorithm with known occurrence data. Our results infer that ACT is widely distrib‐
uted and causes severe damage to four alternative host plants belonging to the family
Rutaceae. The adults, immature stages (eggs and nymphs), galls and the percentage
of infested leaves were significantly higher in shaded than unshaded trees. However,
adult ACTs preferred Kenyan highlands to Victoria Lake and coastal regions. The av‐
erage area under the curve of the model predictions was 0.97, indicating an optimal
model performance. The environmental variables that most influenced the predic‐
tion were the precipitation of wettest quarter, precipitation of wettest month, mean
diurnal range, temperature seasonality and mean temperature of the coldest quarter.
The current prediction of ACT exceeded its existing range, especially in the Western,
Nyanza, Central, Rift valley and Eastern regions of Kenya. The model predicted a
contraction of suitable habitats for a potential spread in 2040 with an inland shift
to higher altitudes in the cooler regions. The potential for further expansion to cli‐
matically suitable areas was more pronounced for the 2080 forecast. These findings
provide relevant information to improve monitoring/surveillance and designing IPM
strategies to limit its spread and damage
