Data/hora: 11/06/2024 06:29:01

Biblioteca(s): 	Embrapa Pantanal.	
Data corrente: 	07/12/2004	
Data da última atualização: 	27/03/2017	
Autoria: 	JENSEN, K. M. V.; JESPERSEN, J. B.; BIRKETT, M. A.; PICKETT, J. A; THOMAS, G.; WADHAMS, L. J.; WOODCOCK, C. M.	
Afiliação: 	Institute of Agricultural Sciences (Denmark); Biological Chemistry Division (Harpenden, U.K); Laboratory for Behavioural Physiology, Institute for Animal Health (Netherlands).	
Título: 	Variation in the load of the horn fly, Haematobia irritans, in cattle herds is determined by the presence or absence of individual heifers.	
Ano de publicação: 	2004	
Fonte/Imprenta: 	Medical and Veterinary Entomology, v.18, n.3, p.275-280, 2004.	
Idioma: 	Inglês	
Conteúdo: 	The distribution of horn flies, Haematobia irritans (L.) (Diptera: Muscidae), in herds of Danish Holstein-Friesian cattle was investigated in two studies conducted during two field seasons. In the first study, highly significant differences in fly distribution between the most and the least fly-susceptible heifers were observed. In one herd, the mean difference between the most fly-susceptible and the most fly-resistant heifers was 268 Ha. irritans speciments. The highest ratio between upper and lower mean fly number was 64.1:1, whereas the lowest was 3.1:1. In the second year, it was demonstrated that the heifers kept their rank in fly attraction over time. The trial clearly demonstrated that some heifers were attracting flies, whereas others, even in the same herd, only carried a few. In the second study, heifers were moved in and out of herds in an attempt to manipulate fly loads in the herds. In year I, one herd (herd A) received four fly-resistant heifers from another herd (herd B), resulting in a drop in the mean number of flies, whereas herd B received four fly-susceptible heifers from herd A, resulting in an elevation of the mean number of flies. In year 2, a similar pattern emerged usingherds C and D, and when the cattle were later returned to their original herds, the fly loads returned to their original distribution. The data presented here show unequivocally that, for horn flies, there can be considerable differences in fly loads for individual heifers within the Holstein-Friesian breed. Furthermore, the overall fly load within herds can be manipulated, and can be reversed. Thus, the distribution in the number of flies within a herd appears to depend on the number of fly resistant or fly-susceptible heifers. The possible role of chemical factors emitted by heifers, i. e. volatile semiochemicals, in determining differences in fly loads is discussed, whereby attractants are emitted by fly-susceptible heifers and enable fies to locate their host, and repellents are emitted by fly-resistant heifers such that the flies are actively repelled from the herd.	
Palavras-Chave: 	Dinamarca; Distribuição; Distribution; Horn fly; Mosca de chifre; Ranking; Semiochemical; Substância química.	
Thesagro: 	Gado; Haematobia Irritans.	
Thesaurus Nal: 	cattle; Denmark.	
Categoria do assunto: 	--	
Registro original: 	Embrapa Pantanal (CPAP)	
Exemplares: 	CPAP - (54383-1) - ADC - SP - PP - SP16594 -  - 16594 - DIS