Virulence of Metarhizium anisopliae to Eggs and Immature Stages of Stomoxys calcitrans

Abstract

Stomoxys calcitrans control is primarily based on the use of chemical products; however, new methods for control have been investigated. Biological control has been proposed as a promising alternative to traditional chemicals. The current study evaluated three methods in vitro to treat S. calcitrans eggs with the fungus Metarhizium anisopliae and assessed the virulence of this fungus to immature stages of this fly. In the first method of egg exposure, eggs were immersed in conidial suspensions and transferred to Petri plates with high humidity. A high mortality was observed in both treated and control groups. In the second method, the eggs were transferred to rearing medium right after immersion in conidial suspensions; the suspensions with highest conidial concentrations, 10(7) and 10(8) conidia mL(-1), caused 96.25% and 100% mortality, respectively. In the third method, the eggs were sprayed with conidial suspensions on the rearing medium. A high mortality was observed at 10(7) and 10(8) conidia mL(-1), 78.3% and 100%, respectively. The second method had the lowest mortality in the control group and was considered the most useful method for evaluating the effect of entomopathogenic fungi on S. calcitrans eggs. While eggs were very susceptible to M. anisopliae infection, larvae and pupae were not.

Antimicrobial activity of Stomoxys calcitransagainst Beauveria bassiana sensu lato isolates

“…All the dishes were sealed with Parafilm®, which was perforated with a hypodermic needle (13 mm × 0.45 mm). The same procedure was used for the control groups, for which the eggs, larvae and pupae were immersed only in a diluent (solution of distilled water and 0.01% Tween 80) (MORAES et al, 2008).…”

“…The eggs and larvae of the control group were immersed in 0.5 ml of the same diluent and transferred to Petri dishes containing filter paper moistened with 2.5 ml of sterile distilled water and rearing medium. The dishes were sealed and the Parafilm® was perforated as described for the first method (MORAES et al, 2008).…”

“…However, few studies have examined the use of entomopathogenic fungi for biological control (WATSON et al, 1995;SKOVGARD & STEENBERG, 2002;MORAES et al, 2008), or the antimicrobial mechanisms of the immature stages of S. calcitrans.…”

Stomoxys calcitrans (Diptera: Muscidae) outbreaks: current situation and future outlook with emphasis on Brazil

“…Biological control agents have also been considered as an option, emphasizing the use of entomopathogenic fungi (MORAES et al, 2008;ALVES et al, 2012) and bacterial isolates, such as Bacillus thuringiensis (LYSYK & SELINGER, 2012). However, their use is not a short-term option.…”

“…Running applied research, which includes biological control (MORAES et al, 2008(MORAES et al, , 2010, population monitoring, and chemical control, should lead to the identification of potentially useful alternatives for controlling the parasite and preventing outbreaks. Unfortunately, such alternatives are not yet available and more time is required for their development before they can be applied in practice.…”