Genetic structuration of Rastrococcus invadens populations in Senegal (Casamance and Thies)

Abstract

Rastrococcus invadens (Homoptera, Pseudococcidae) or cochineal is an insect pest of mango trees and several other fruit trees including citrus. It belongs to the branch of Arthropods, class of insects, to the order of orthoptera, to the super family of Coccoidea and to the family Pseudococcidae. The cochineal is native to Southeast Asia and was first identified in Dakar (Senegal) in 1995. Since then it has been widely used throughout the country and more particularly in the two most fruit-producing regions: Casamance and Thies. To study the genetic structure of the populations of Rastrococcus invadens, we have chosen the three species of host plants most attacked, namely the mango tree, the lemon tree and the orange tree. On each foot, we randomly harvested 10 insects. This allows us to have a total of 60 individuals, including 30 in the Casamance natural region and 30 in the Thies region. Samples are coded according to the area and type of plant in which they were collected using the first letter of the genus name, the first letter of the region of origin and the first letter of the host plant. The same individuals stored in 70% alcohol were used for extractions, PCR (Chain Reaction Polymerase) and sequencing. The analysis is done by several software in order to output the different parameters of the study.The results obtained in genetic diversity show six groups of individuals according to host plants and study areas which confirm those of morphometry. However, since these groups have very small genetic distances, they constitute a single species of Rastrococcus invadens.