Genetic similarity of eggplant shoot and fruit borer, Leucinodes orbonalis, populations

Shoot and fruit borer, Leucinodes orbonalis (Guenee) (Pyraustidae: Lepidoptera), has become a production constraint in all eggplant (Solanum melongena Linn. [Solanaceae])-growing countries. In India, transgenic eggplants expressing Bacillus thuringiensis Cry toxins have been tested in fields by private- and public-sector agencies. Understanding population diversity is important in designing strategies for better pest management. In the present investigation, random-amplified polymorphic DNA markers were used to assess the genetic diversity of L. orbonalis population collected from different field locations in the Tamilnadu State of India. Of 17 random-amplified polymorphic DNA primers screened, only 11 primers generated polymorphic bands (up to 14 bands). According to their level of similarities, only two major clusters with no variation among population were deduced. Our results indicated that there is a steady genetic flow among the present population of L. orbonalis alleviating genetic variation, which may be attributed to passive and active dispersal of the insect besides absence of host-induced variations among the population. As molecular variability of L. orbonalis population is an important consideration for shoot and fruit damage of the eggplant, constant monitoring is essential to study the possible development of Cry protein resistance in L. orbonalis.