Molecular characters of a bark beetle, Xylosandrus crassiusculus associated with avocado using 28S rDNA from regions of South Africa

South Africa is a significant producer and exporter of avocados in the world. Xylosandrus crassiusculushas was found on mainland Africa for many years but the present study represents the first record of bark beetle in South Africa in Limpopo Province. Its presence infesting important agronomic tree crops such as avocado suggests that it requires further study. Therefore, this molecular study was conducted in 2022 at the University of Limpopo to identify the bark beetle in the South African avocado orchard. The recovered bark beetle was isolated from the bark of avocado in Magoebasklo of region in Limpopo Province. Then its DNA was extracted using the Chelex method, and the phylogenetic position of the beetle was studied using 28S rDNA. The Nblast analysis based on the large subunit ribosomal DNA showed 99% similarity with a population of Xylosandrus crassiusculus from South Africa (MT229960), USA (GU808593), and Taiwan (MT120970). In addition, phylogenetic analysis using the maximum likelihood method as implemented in mega x software was done. The phylogenetic analysis put the South African populations of X. crassiusculus together with other X. crassiusculus with a 100-bootstrap value. In conclusion, the results showed that 28S could detect the X. crassiusculus, and was verified by the molecular method.