Culex quinquefasciatus  Egg Membrane Alteration and Ovicidal Activity of Cipadessa baccifera (Roth) Plant Extracts Compared to Synthetic Insect Growth Regulators

Govindaraju Ramkumar,1,* Sengodan Karthi,1,2,* Muthugounder S Shivakumar,1 Eliningaya J Kweka3,4 1Molecular Entomology Laboratory, Department of Biotechnology, Periyar University, Salem 636 011, Tamil Nadu, India; 2Department of Biochemistry, Centre for Biological Sciences, K.S. Rangasamy College of Arts and Science (Autonomous), Tiruchengode 637215, Tamil Nadu, India; 3Division of Livestock and Human Diseases Vector Control, Mosquito Section Tropical Pesticides Research Institute, Arusha, Tanzania; 4Department of Medical Parasitology and Entomology, Catholic University of Health and Allied Sciences, Mwanza, Tanzania*These authors contributed equally to this workCorrespondence: Eliningaya J KwekaDivision of Livestock and Human Diseases Vector Control, Mosquito Section Tropical Pesticides Research Institute, P.O. Box 3024, Arusha, TanzaniaEmail pat.kweka@gmail.comBackground: Insecticide resistance among mosquito vectors for synthetic insecticides still remains a major problem for control efforts. This study assessed the ovicidal potential of crude solvent extracts from the medicinal plant Cipadessa baccifera comparatively to standard registered synthetic insect growth regulators (IGR) on freshly laid eggs of Culex quinquefasciatus.Method: Five plant extracts were prepared using different solvents. The batches of eggs were exposed to different concentrations of each solvent extract comparatively to synthetic IGR. The hatched eggs of Cx. quinquefasciatus were subjected to different concentrations. The first instars that emerged from the eggs were counted daily. The egg hatching inhibition was observed 24, 48 and 72 hrs post treatment. The desiccation median time (DT50 and DT90) was calculated.Results: The percent egg hatching inhibition was inversely proportional to the concentration of extracts. The morphological damage to the eggs was observed. Among five solvent extracts, acetone extracts showed the highest ovicidal activity. The changes in eggshell morphology were observed. The maximum ovicidal activity was observed in acetone extracts with DT50 value of 1.70 hrs (0.91–2.22). The methanol plant extract using gas chromatography-mass spectrometry identified 14 compounds.Conclusion: These results suggest that the acetone extracts of C. baccifera have the potential to be used as an ovicidal agent for controlling mosquito populations in aquatic stages. The biodegradability of the extracts has the advantage of being eco-friendly.Keywords: mosquito, egg hatching, insect growth regulators, ovicidal activity plant extracts