A Case Report on Natural Control of Eggplant Powdery Mildew Disease by Illeis cincta (Fabricius, 1798) (Coleoptera: Coccinellidae) in Peradeniya, Sri Lanka

Mycophagous coccinellids which consume fungi as a part of food or their primary food, are crucial biocontrol agents. The current study demonstrates the effectiveness of a naturally occuring population of Illeis cincta (Fabricius, 1798) (Coleoptera: Coccinellidae) in controling eggplant powdery mildew disease in an eco-friendly eggplant plot at Meewathura agricultural farm, University of Peradeniya. As a sudden hike in coccinellid numbers on eggplant leaves infested by fungal disease with a powdery appearnce was observed in early March 2022, a systmatic investigation was done using sixteen randomly selected plants. Observations were made twice a week for five weeks to record the number of infected and healthy leaves to estimate the disease severity and index while quantifying the abundance of coccinellid species, eggs, larvae and adults on all leaves of the selected plants. Identifification revealed powdery mildew as the fungal disease affecting eggplant while I. cincta was the coccinellid beetle species. Total abundance of I. cincta initially increased with time, but declined gradually with decreasing disease severity. Disease severity positively correlated with I. cincta population density, while disease incidence correlated negatively with I. cincta population density. The study highlights the importance of conserving the coccinelid, I. cincta in controlling eggplant powdery mildew disease in eco-friendly cropping systems.