Infection of Anopheles gambiae mosquitoes with entomopathogenic fungi: effect of host age and blood-feeding status

Abstract

Physiological characteristics of insects can influence their susceptibility to fungal infection of which age and nutritional status are among the most important. An understanding of host–pathogen interaction with respect to these physiological characteristics of the host is essential if we are to develop fungal formulations capable of reducing malaria transmission under field conditions. Here, two independent bioassays were conducted to study the effect of age and blood-feeding status on fungal infection and survival of Anopheles gambiae s.s. Giles. Mosquitoes were exposed to 2 × 1010 conidia m−2 of oil-formulated Metarhizium anisopliae ICIPE-30 and of Beauveria bassiana I93-825, respectively, and their survival was monitored daily. Three age groups of mosquitoes were exposed, 2–4, 5–8, and 9–12 days since emergence. Five groups of different feeding status were exposed: non-blood-fed, 3, 12, 36, and 72 h post-blood feeding. Fungal infection reduced the survival of mosquitoes regardless of their age and blood-feeding status. Although older mosquitoes died relatively earlier than younger ones, age did not tend to affect mosquito susceptibility to fungal infection. Non-blood-fed mosquitoes were more susceptible to fungus infection compared to all categories of blood-fed mosquitoes, except for those exposed to B. bassiana 72 h post-blood feeding. In conclusion, formulations of M. anisopliae and B. bassiana can equally affect mosquitoes of different age classes, with them being relatively more susceptible to fungus infection when non-blood-fed.

Evaluation of culture filtrates of Culicinomyces clavisporus: Mycoadulticide for Culex quinquefasciatus, Aedes aegypti and Anopheles stephensi

“…Moreover, in the laboratory limited horizontal transfer of fungal conidia between mosquitoes has shown to be possible during copulation (Scholte et al 2004) and may contribute to the spread of the fungus through the mosquito population, thereby increasing the infection rates and the effectiveness of these biological control agents. Mnyone et al (2011) developed fungal formulations capable of reducing malaria transmission under field conditions. The Fusarium pallidoroseum is one of the alternative biological control agents of adult mosquitoes (Mohanty et al 2008).…”

“…The residual sprays of fungal biopesticides might replace or supplement chemical insecticides for malaria control, particularly in areas of high insecticide resistance (Blanford et al 2005). Whilst the use of entomopathogenic fungi against mosquitoes has provided encouraging results under controlled laboratory conditions (Howard et al 2010;Blanford et al 2005;Mnyone et al 2011.…”

Effects of Beauveria bassiana on Survival, Blood-Feeding Success, and Fecundity of Aedes aegypti in Laboratory and Semi-Field Conditions

“…Larval diet is reported to affect mosquito larval survival in the presence of entomopathogenic fungi, 29 and mosquitoes blood-fed before being exposed to fungus have been observed to live longer than non-blood fed, fungus-exposed mosquitoes. 30,31 However, little more is known about the influence of other factors.…”

Adulticidal and larvicidal activity of Beauveria bassiana and Metarhizium anisopliae against housefly, Musca domestica (Diptera: Muscidae), in laboratory and simulated field bioassays

“…However, majority of the studies concerning entomopathogenic fungi deal with agricultural pests (as reviewed in Shah and Pell 2003;Goettel et al 2005). While among the vectors, many studies target mosquito (Mnyone et al 2010;Leles et al 2010) and relatively few studies have been conducted on housefly control. Bellini et al (1992) studied the dose mortality assay with Entomophthora muscae on housefly while Maitland (1994) reported its natural prevalence in parts of Europe and America.…”