Distribution, degree of damage and risk of spread of Trioza erytreae (Hemiptera: Triozidae) in Kenya

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 distributed 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 average area under the curve of the model predictions was 0.97, indicating an optimal model performance. The environmental variables that most influenced the prediction 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 climatically 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.

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

“…The estimates of climatic suitability presented in the herein study are consistent with the known distribution of the African citrus psyllid outside of continental Europe, i.e., this species is abundant in cool areas and absent or at least rare in the warm lowlands of sub-Saharan Africa (Aubert et al 1988; Tamesse et al 1999; Aidoo et al 2019) and La Réunion Island (Aubert et al 1980). Strikingly, the models predicted the area invaded by T. erytreae in continental Europe with high accuracy (Fig.…”

Model‐based prediction of the potential geographical distribution of the invasive coconut mite, Aceria guerreronis Keifer (Acari: Eriophyidae) based on MaxEnt

“…Climate change plays an important role in the distribution of species leading to either expansion or reduction of suitable habitats (Aidoo et al, 2019; Ajene et al, 2020; Sung et al, 2018; Thomson et al, 2010; Velásquez‐Tibatá et al, 2013). Global warming is expected to change the distribution of species around the world, by changing their natural habitats (Velásquez‐Tibatá et al, 2013).…”

Potential areas of spread of Trioza erytreae over mainland Portugal and Spain

“…Hence, efforts in predicting the current and future geographical distribution of HLB and its psyllid vectors have been made for the sake of developing and applying preventive measures and efficient control strategies (e.g. Narouei-Khandan 2016; Aidoo et al 2019;Ajene et al 2021;Benhadi-Marín et al 2020;Urbaneja-Bernat et al 2020). Moreover, one of the psyllid vectors alone, T. erytreae, also reduces crop yield causing death in up to 90% of untreated young plants because of the formation of open gall-like structures and strong deformation of leaves (Cocuzza et al 2017).…”