Effects of the botanical compound p-anisaldehyde on horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae) repellency, mortality, and reproduction

Authors: Showler, Allan; Harlien, Jessica

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2017
Publication Date: 1/14/2018
Citation: Showler, A., Harlien, J.L. 2018. Effects of the botanical compound p-anisaldehyde on horn fly, Haematobia irritans irritans (L.) (Diptera: Muscidae) repellency, mortality, and reproduction. Journal of Medical Entomology. 55:183-192. https://doi.org/10.1093/jme/tjx183.
DOI: https://doi.org/10.1093/jme/tjx183

Interpretive Summary: The horn fly is an economically important blood-feeder that mainly attacks cattle worldwide. As resistance to conventional insecticides increases, alternative control tactics are being investigated. p-Anisaldehyde occurs in many plants and it is bioactive against some arthropods. We developed a series of bioassays for assessing a range of horn fly responses to chemicals. We found that p-anisaldehyde was lethal to horn fly eggs at 0.00001% and possibly at lower concentrations. Mixed into cow manure, p-anisaldehyde reduced horn fly larvae by as much as 100%. p-Anisaldehyde caused some immobilization of adult horn flies when exposed by direct contact with spray droplets and by volatiles. LD50 and LD90 values for direct contact with adults are reported. Complete horn fly mortality was achieved by exposure to volatiles and exposure to volatiles is more lethal to adult horn flies than contact with droplets. Although horn flies were not repelled, the compound completely deterred feeding from cotton pads soaked in bovine blood. Exposure to sublethal concentrations of p-anisaldehyde did not affect horn fly egg production and hatching.

Technical Abstract: The horn fly, Haematobia irritans irritans (L.), is an economically important obligate blood-feeding ectoparasite that mainly attacks cattle worldwide. As resistance to conventional insecticides increases, alternative control tactics are being investigated. p-Anisaldehyde occurs in many plants and it is bioactive against some arthropods. We developed a series of bioassays that are effective for assessing a range of horn fly responses to chemicals. In our study, p-anisaldehyde was lethal to horn fly eggs at 0.00001% and possibly lower concentrations. Mixed into cow manure, 5,000 – 20,000 ppm p-anisaldehyde reduced horn fly larvae by 85.4% – 100%. p-Anisaldehyde caused some immobilization of adult horn flies when exposed by direct contract with spray droplets and by volatiles. Adult mortality was 90% – 100% in response to 5% – 10% concentrations by 30 min, and LD50 and LD90 values are reported. Complete horn fly mortality was achieved by exposure to volatiles from 0.75% p-anisaldehyde by 3 h in an enclosed space; exposure to volatiles is more lethal to adult horn flies than droplets. Although horn flies were not repelled, the compound completely deterred feeding from cotton pads soaked in bovine blood. Exposure to sublethal concentrations of p-anisaldehyde did not affect horn fly egg production and hatching.