Discovery, Development, and Evaluation of a Horn Fly-Isolated (Diptera: Muscidae) Beauveria bassiana (Hypocreales: Cordyciptaceae) Strain From Florida, USA

Abstract

The horn fly, Haematobia irritans (L.) is an important cattle pest and traditionally has been managed using insecticides; however, many horn fly populations are insecticide-resistant in United States. Use of alternative control techniques has been limited because of the challenges of managing a fly pest on pastured cattle. After the discovery of a wild horn fly infected with Beauveria bassiana in Florida, the fungus was cultured and evaluated for efficacy against laboratory-reared horn flies. This fungal strain was selected for increased virulence by passage through laboratory-reared horn fly hosts to shorten interval from infection to fly death and subsequent conidia formation, properties important to future use of the fungus as a biological control agent against horn flies. After seven passages through horn fly hosts, fly mortality was not significantly accelerated as evaluated through LT50 values, but conidia were readily produced from these killed flies. Although further development is needed to improve fungal efficacy, this fungal strain holds promise as a biological control agent for inclusion in horn fly integrated pest management programs.

Susceptibility of the adult house fly (Diptera: Muscidae) and 3 of its principal parasitoids (Hymenoptera: Pteromalidae) to the GHA strain of Beauveria bassiana and 4 isolates from field-collected muscid flies

“…The GHA used in our study was taken directly from a stock of conidia provided by the manufacturer, while White et al (2021) used BotaniGard (Certis Biologicals, Columbia, MD) as their source for GHA, but they passed it through house flies and used the isolate taken from the fly cadavers. While not always the case (Holderman et al 2017, White et al 2021), there are indications that passage back through an intended insect host can increase virulence for certain strains (Daoust and Roberts 1982, Butt et al 2006, Song and Feng 2011). The effects of in vivo and in vitro subcultures should be rigorously studied for any strain being considered for biocontrol.…”

10. Public-private partnership enabled use of anti-tick vaccine for integrated cattle fever tick eradication in the USA

“…As adult flies are able to oviposit 3-5 days post eclosion a rapid death rate is important for their control. To accelerate mortality, Holderman et al (2017) passaged a horn fly-derived isolate of B. bassiana (EN1) back through adult horn flies. However, after seven passages they did not find any increase in virulence from this selection process.…”

1. Livestock pests and vector-borne diseases – a much neglected subject

“…A number of studies have investigated EPF as a potential alternative management tool for the horn fly (Angel-Sahagún et al 2005;Bawer et al 2014;Galindo-Velasco et al 2015;Holderman et al 2017;Leemon 2012;Lohmeyer and Miller, 2006;Mochi et al 2009Mochi et al , 2010a. Most of these studies involved laboratory evaluations of different isolates or formulations of M. anisopliae s.l., B. bassiana, I. fumosorosa or I. farinosa against different stages of horn fly (Angel-Sahagún et al 2005;Bawer et al 2014;Holderman et al 2017;Lohmeyer and Miller, 2006;Mochi et al 2010a,b). Generally, isolates of M. anisopliae and B. bassiana are the most virulent for horn flies, but mortality after treatment, as with other flies, is slow.…”