Mortality of horn fly (Diptera: Muscidae) larvae in bovine dung supplemented with loline alkaloids from tall fescue.
Larvae of arthropod ectoparasites of livestock, such as the horn fly, Haematobia irritans (L.), may be exposed to acyl-loline alkaloids in dung of ruminant livestock ingesting herbage of the tall fescue (Festuca arundinacea Schreb.)-endophyte association [Neotyphodium coenophialum (Morgan-Jones & W. Gams) Glenn, Bacon & Hanlin comb. nov.]. Biological activity of alkaloid-supplemented bovine dung was assayed by growth, development, and survival of 1st instars of horn fly. An extract from tall fescue seed, containing N-formyl loline (NFL), N-acetyl loline (NAL), and loline (59:21:20 by mass, respectively) caused 100% mortality of horn fly larvae when dung was supplemented at > or = 100 micrograms/g. Probit analysis of data corrected for natural mortality indicated a LD50 of 30 micrograms/g (95% fidicial limits: 20-49 micrograms/g). When horn fly larvae were introduced to dung supplemented with up to 50 microM of acyl-loline derivatives, mortality of larvae varied significantly between alkaloids (P < 0.0001). Probit analysis indicated that NFL [LD50: 34 microM (95% fidicial limits: 3-53 microM)] was more toxic than NAL [LD50: 46 microM (0-83 microM)], and that loline hydrochloride was not toxic.
Department of Agronomy, University of Kentucky, Lexington 40546-0091, USA.
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Dougherty
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Knapp
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Bush
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Maul
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Van Willigen
D000470:Alkaloids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology* / Q000517:prevention & control; D004478:Ectoparasitic Infestations / Q000517:prevention & control / Q000662:veterinary*; D005243:Feces / Q000469:parasitology*; D007300:Insect Control / Q000379:methods*; D007814:Larva; D009117:Muscidae; D010572:Pest Control, Biological / Q000379:methods; D010936:Plant Extracts / Q000737:chemistry; D006109:Poaceae
D000470:Alkaloids; D010936:Plant Extracts; C059478:loline