Histological changes in the larvae of the domestic mosquito Culex pipiens treated with the entomopathogenic fungus Beauveria bassiana

Abstract

The Culicidae are biting insects that are most harmful to people. They are almost all blood-suckers, and are responsible for the spread of many important diseases such as malaria, yellow fever and elephantiasis. Entomopathogenic microorganisms occupy an important place among the alternative methods of fighting against pests insect. The fungus, Beauveria bassiana is an entomopathogenic agent naturally present in the ecosystems and offers a very interesting potential for controlling populations of mosquitoes. Our study aims at showing the 4 th stage larvae histological changes of the domestic mosquito Culex pipiens, treated with the entomopathogenic fungus B. bassiana in suspension which corresponds to a dose of 10 7 spore/mL. In fact, after developing the individuals in the fungal solution, histological study was carried out on the following parts; cuticle, intestine, adipose tissue and hemolymph. The histological studies showed many alterations and malformation in the treated 4 th instar larvae body and tissues. The infection affected the different parts of the body, especially the cuticle, the adipose cells, and midgut, in addition to the development and the colonization of B. bassiana inside tissues. The application of B. bassiana on the cuticle of the larvae was dependent on an apparent disturbance in the structure of the cuticle or the degeneration of its different parts. The fungus infection does not stop at the level of the body walls, so it even goes to adipose tissue, epidermal cells and intestine. Based on these results, B. bassiana could be suggested as suitable biocontrol agent against C. pipiens.

Laboratory evaluation of the pathogenic effect of fungus Beauveria bassiana (Balsamo) on the cuticular structure of fourth instar larvae of Anopheles stephensi (L.).

“…The germination of conidiospore was observed in entire haemolymph area leaving all tissues lysed as if rotten mass of cells providing substratum for fungal growth. Germination of conidia on integument was similar to that reported for Culex quinquefasciatus 16 .The detection of endocuticular lysis and infection of epidermis was also reported 17,18 .…”

Host-Environment Interplay Shapes Fungal Diversity in Mosquitoes

“…In contrast, the fungal diversity observed in mosquito carcasses, from which we had removed the heads to exclude any fungi captured on the mouth brushes during feeding, was lower and contained communities distinct from those in the larval guts and breeding water. Approximately one-half of the OTUs with a preference for carcass compared to gut were putative animal pathogens, suggesting that these OTUs either interact with the carcass by attaching to the cuticle or infect the carcass through the gut after ingestion ( 79 – 85 ). These included OTUs assigned to the species C. rosea , a fungal entomopathogen of several insect hosts, including leafhoppers, whiteflies, and alfalfa weevils ( 86 – 88 ), and Alternaria porri , which causes mortality in green apple aphids and delays hatch rates in egg masses of the European corn borer ( 89 , 90 ).…”

Larvicidal, Histopathological, Antibacterial Activity of Indigenous Fungus Penicillium sp. Against Aedes aegypti L and Culex quinquefasciatus (Say) (Diptera: Culicidae) and Its Acetylcholinesterase Inhibition and Toxicity Assessment of Zebrafish (Danio rerio)

“…aegypti and found different histological changes such as the gastric caeca, muscles shrinkage, damaged and disorganized nerve cord ganglia. Earlier, Farida et al (2018) studied the B. bassiana metabolites toxicity on 4th instar larvae of Cx. pipiens and observed many histological changes and malformation in the treated larval body and tissues, especially in the adipose cells, cuticles and midgut.…”