Submitted to: Journal of Insect Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/8/2005
Publication Date: 12/31/2005
Citation: Angel-Sahagun, C.A., Lezama-Gutierrez, R., Molina-Ochoa, J., Galindo-Velasco, E., Lopez-Edwards, M., Rebolledo-Dominguez, O., Cruz-Vazquez, C., Reyes-Velazquez, W.P., Skoda, S.R., Foster, J.E. 2005. Susceptibility of biological stages of the horn fly, Haematobia irritans, to entomopathogenic fungi (hyphomycetes). Journal of Insect Science. 5:1-8. Interpretive Summary: Horn flies are economically important, blood-feeding pests of cattle and other mammals. They were introduced to the Western Hemisphere, have become widely distributed in North and South America, and are estimated to cause $1 billion in annual losses to livestock producers. Chemical control of horn flies is currently very unreliable. Therefore, other pest management systems must be designed. We studied the susceptibility of horn flies (egg, pupal, and adult stages) to several isolates of three entomopathogenic fungi, Metarhizium anisopliae, Beauveria bassiana, and Paecilomyces fumosoroseus. Some isolates of M. anisopliae and P. fumosoroseus caused significant mortality in horn flies; three isolates of M. anisopliae warrant further consideration as biological control agents useful for incorporation into pest management strategies.
Technical Abstract: The susceptibility of the egg, pupa, and adult of Haematobia irritans (L.) (Diptera: Muscidae) to isolates of the fungi Metarhizium anisopliae (Metsch.) Sor., Beauveria bassiana (Bals.) Vuill., and Paecilomyces fumosoroseus (Wize) Brown and Smith, was evaluated under laboratory conditions. Groups of 20 eggs than 4 h old, pupae less than 48h old and adults were sprayed with a conidial suspension of each isolate. Eggs, pupae and adults of horn fly were susceptible to these entomopathogenic fungi. For treated eggs, the isolates Ma3, Ma 15, Ma25, Pfr1, and Pfr8 reduced adult emergence to 3.8% to 6.3% in comparison with the control (72%). The mortality of pupae infected by the isolates Ma2, Ma25, and Pfr10 ranged between 50% and 71.3%. Mortality of adults after treatment with the isolates Ma6, Ma 10, Ma 14, Ma 15, Pfr 1, Pfr 9, Pfr 10, Pfr 11, and Pfr12 were higher than 90%. The isolate Ma6 produced the lowest LC50 against adult horn flies (8.08 x102conidia/ml). These findings supported the hypotheses that isolates of M. anisopliae, and P. fumosoroseus are pathogenic against the different biological stages of horn flies by reducing adult emergence when applied on groups of eggs and pupae, and producing mortality when applied to adults.