J. Mendes et Ax. Linhares, Diapause, pupation sites and parasitism of the horn fly, Haematobia irritans, in south-eastern Brazil, MED VET ENT, 13(2), 1999, pp. 185-190
In order to verify the occurrence of diapause, preference for pupation site
s and hymenopteran parasitism, the pupae of the horn fly, Haematobia irrita
ns (Diptera: Muscidae), were collected from undisturbed cattle dung pats in
pastures, and adults of the fly were sampled from cattle in Sao Paulo Stat
e, south-eastern Brazil, from April 1993 to July 1994. Diapause was verifie
d in 7.7% of pupae sampled from pastures in June and July of 1993 and in 9.
9% of those sampled in May, June and July of 1994 (overall rate of 9.1%). A
pproximately 8.3% of the pupae were parasitized by microhymenopterans, most
ly Spalangia nigroaenea and S. cameroni (Hymenoptera: Pteromalidae). Horn f
ly pupae were found almost exclusively inside the pat or in the soil immedi
ately beneath and adjacent to it, and very few were collected elsewhere. Pu
pa mortality was 54.4% and did not change significantly during the year, bu
t mortality was greater among pupae collected in pastures when compared to
those obtained from experimental pats, lacking natural enemies.