Abstract
BackgroundThe entomopathogenic fungus Metarhizium anisopliae shows great promise for the control of adult malaria vectors. A promising strategy for infection of mosquitoes is supplying the fungus at plant feeding sites.MethodsWe evaluated the survival of fungus-exposed Anopheles gambiae mosquitoes (males and females) fed on 6% glucose and on sugars of Ricinus communis (Castor oil plant) and Parthenium hysterophorus (Santa Maria feverfew weed). Further, we determined the feeding propensity, quantity of sugar ingested and its digestion rate in the mosquitoes when fed on R. communis for 12 hours, one and three days post-exposure to fungus. The anthrone test was employed to detect the presence of sugar in each mosquito from which the quantity consumed and the digestion rates were estimated.ResultsFungus-exposed mosquitoes lived for significantly shorter periods than uninfected mosquitoes when both were fed on 6% glucose (7 versus 37 days), R. communis (7 versus 18 days) and P. hysterophorus (5 versus 7 days). Significantly fewer male and female mosquitoes, one and three days post-exposure to fungus, fed on R. communis compared to uninfected controls. Although the quantity of sugar ingested was similar between the treatment groups, fewer fungus-exposed than control mosquitoes ingested small, medium and large meals. Digestion rate was significantly slower in females one day after exposure to M. anisopliae compared to controls but remained the same in males. No change in digestion rate between treatments was observed three days after exposure.ConclusionsThese results demonstrate that (a) entomopathogenic fungi strongly impact survival and sugar-feeding propensity of both sexes of the malaria vector An. gambiae but do not affect their potential to feed and digest meals, and (b) that plant sugar sources can be targeted as fungal delivery substrates. In addition, targeting males for population reduction using entomopathogenic fungi opens up a new strategy for mosquito vector control.
Highlights
The entomopathogenic fungus Metarhizium anisopliae shows great promise for the control of adult malaria vectors
Survival of M. anisopliae-infected An. gambiae mosquitoes fed on plant sugars Infection with M. anisopliae reduced the survival of both sexes of An. gambiae with 100% mortality occurring within seven days compared to ≥ seven days with uninfected mosquitoes irrespective of the nutritional source (Figure 1)
The daily risk of death for both sexes was eight-fold greater on 6% glucose; four-fold and eight-fold greater on R. communis and two-fold greater for both sexes on P. hysterophorus relative to their controls (Table 1)
Summary
The entomopathogenic fungus Metarhizium anisopliae shows great promise for the control of adult malaria vectors. A promising strategy for infection of mosquitoes is supplying the fungus at plant feeding sites. Studies have shown that fungal pathogens reduce survival of Anopheles mosquitoes to a level that prevents transmission of malaria parasites [1,2,3]. The fungi achieve this by reducing mosquito blood feeding [4,5] and fecundity [5]. Sugars from some of these plants promote longer survival of both sexes, which enhances the vectorial capacity of females [16,22] and fitness and reproductive capacity of the males [21]. As sugar feeding is central in the biology of adult mosquitoes, it is imperative to assess whether infection of mosquitoes with entomopathogenic fungi impacts sugar feeding
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
