First report of the occurrence of Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae), an invasive species in Nigeria, West Africa

Abiola Olufunke Oke,Olufemi J Alabi,Abiola Adeyinka Oladigbolu,Mamoudou Sétamou,Madhurababu Kunta

doi:10.1038/s41598-020-66380-4

Abstract

The Asian citrus psyllid (ACP; Diaphorina citri) is the vector of Candidatus Liberibacter asiaticus (CLas) that is associated with the devastating Huanglongbing (HLB; citrus greening disease). This pest of Asian origin has spread into the Americas and more recently into a few countries in East Africa. During recent surveys, suspect ACP adults and nymphs were recorded for the first time infesting citrus trees in southwest Nigeria. Morphological identification and DNA barcoding confirmed the samples to be D. citri. Analysis of the obtained sequences revealed that the ACP recorded in Nigeria clustered with other taxa in the previously identified B1 clade that consists of populations from different continents. The presence of the endosymbionts Ca. Carsonella ruddii and Ca. Profftella armatura in ACP from Nigeria was also confirmed by PCR and Sanger sequencing. The ACP individuals were assayed for the presence of CLaf, CLam and CLas by qPCR, but none of the insects tested positive for any of the Liberibacters. The prolific nature of ACP and the tropical climate prevailing in the citrus-producing areas of Nigeria and other West African countries may favor its rapid spread and population increase, thus posing a grave threat to the sustainability of citriculture in these countries.

Highlights

Citrus is one of the world’s most important economic crops and the most widely grown fruit tree in Africa
Using previously described features[20,21,22], and based on comparisons with voucher specimens, the field-collected insect samples were morphologically identified as D. citri (Fig. 1)
Voucher specimens of these samples have been deposited at the TAMUK-CC in Weslaco, Texas Entomology Laboratory, and at National Horticultural Research Institute (NIHORT), Ibadan, Nigeria

Summary

Introduction

Citrus is one of the world’s most important economic crops and the most widely grown fruit tree in Africa. Among the arthropod pests affecting citrus, the sap sucking hemipteran pests are of great concern Feeding damage by these insects due to uptake of plant sap causes distortion, wilting, premature leaf drop, reduction of fruit sizes, and occasional tree death[4]. Some of these sap-sucking pests are documented vectors of pathogens of economically important citrus diseases such as Tristeza, Citrus Variegated Chlorosis, and Huanglongbing (HLB) or Citrus Greening, among others[5,6]. Citrus commodity pest surveys were conducted in southwestern Nigeria to determine the presence or absence of D. citri and if present, to diagnose the sampled individuals for Liberibacter

Methods

Results

Conclusion