Novel development of Lecanicillium lecanii-based granules as a platform against malarial vector Anopheles culicifacies

Abstract

Mosquitoes are infectious vectors of a wide range of pathogens and parasites thereby transmitting several diseases like Malaria, Dengue, Chikungunya, Zika, and Japanese Encephalitis posing a major public health concern. Mostly synthetic insecticides are usually applied as a primary control strategy to manage vector-borne diseases. However excessive and non-judicious usage of such chemically derived insecticides has led to serious environmental and health issues owing to their biomagnification ability and increased toxicity towards non-target organisms. In this context, many such bioactive compounds originating from entomopathogenic microbes may serve as an alternative and environmentally benign tool for vector control. In the present paper, the entomopathogenic fungus Lecanicillium lecanii was processed to make the granules. Developed 4% LL granules have been characterized using the technique of Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM). The developed formulation was also subjected to an accelerated temperature study at 40° C and was found to be stable for 3 months. Further, GCMS of the L. lecanii was also performed to screen the potential biomolecules present. The developed formulation was found to be lethal against Anopheles culicifacies with an LC50 value of 11.836 µg/mL. The findings from SEM and histopathology also substantiated the mortality effects. Further SEM EDX studies revealed that treated mosquitoes have lower nitrogen content which is correlated to a lower level of chitin whereas the control one has higher chitin content and healthy membranes. The developed LL granule formulation exhibited high toxicity against Anopheles mosquitoes due to its selective toxicity, thereby minimizing the toxicity toward non-target organisms. The granule formulations can be used as an effective biocontrol strategy against malaria-causing mosquitoes.