Showing papers by "Fernando Ferreira published in 2003"

Larval Behavioral Diapause Regulates Life Cycle of Amblyomma cajennense (Acari: Ixodidae) in Southeast Brazil

Abstract: Previous studies have determined that Amblyomma cajennense (F.) produces one generation per year in Southeastern Brazil. Larvae predominate from April to July, nymphs from July to October, and adults from October to March. In the current study, we observed engorged females, their eggs, and respective larvae in the field. Engorged females were released in grass plots under natural conditions, at monthly intervals, from October 2000 to March 2001. Preoviposition periods lasted 1–2 wk, and mean egg incubation periods lasted 5–7 wk. Consequently, larvae hatched at different periods from early December 2000 to early April 2001. However, all hatched larvae stayed confined to the plot ground, under the vegetation, until late April or early May 2001, when some larvae were seen questing on top of vegetation for the first time. Thereafter, larvae were always seen on this questing position until August 2001, when all larvae had died on the plots. In addition, premolt period data of engorged larvae and nymphs held in laboratory at different temperatures were used to construct a premolt mathematical model, which was applied to reported seasonal dynamic data of A. cajennense in the field. The premolt model indicated that the field intervals between larvae and nymphs and between nymphs and adults are controlled solely by nondiapause events, such as ground temperature. We concluded that the 1-yr generation pattern of A. cajennense in Southeastern Brazil is primarily controlled by larval behavioral diapause, shown by larvae born during spring/summer months, before their activity period at next autumn.

Avaliação de dois métodos de diagnóstico precoce de gestação em ovelhas: ultra-sonografia transretal e detector de prenhez para pequenos ruminantes (DPPR-80®)

Abstract: Ultrasonography was perfomed in 88 ewes from Nucleo de Pesquisas Zootecnicas Sudoeste - Instituto de Zootecnia, Sao Paulo state, from march to may , 2001. Animals were examined from 19o to 33o days of pregnancy by transrectal ultrasonography in alternate days examinations, and by pregnancy detector for small ruminants (DPPR-80O) from 25o to 45o day. Positive diagnostic by transretal ultrasonography was obtained after yolk sac visualization. The embryo heartbeat was observed after 25 day of pregnancy. The positive diagnostic was obtained by pregnancy detector when embrionic heart was 160 to 200 beats/minute. Births confirmed the examinations. Three abortions ocurred during the experiment and these females were excluded from the group. From 85 ewes examined, 64 lambed. The transrectal ultrasonography accuracy in 19o day of pregnancy was 35,29%, with higher rate (82,53%) in 31o day. The doppler accuracy in 25o day was 24,71% and 34,12.00% in 45o day. Embryo heartbeat was detected by transrectal ultrasonography after 21 days of pregnancy and the first placentoms were observed after 25 days of pregnancy. In conclusion, transrectal ultrasonography was better than doppler in early pregnancy diagnosis in sheep.

Avaliação de dois métodos de diagnóstico precoce de gestação em ovelhas: ultra- sonografia transretal e detector de prenhez para

Abstract: dia de gestacao foi observado tambOm obatimento cardiaco embrionAErio, cuja frequŒncia O de 160 a 200batimentos por minuto. Esta observacao foi dada comodiagnostico de gestacao. Os nascimentos confirmaram os resultadosdos exames. Dentre 88 fŒmeas acasaladas, 3 abortaram durante oexperimento e foram retiradas do grupo. Das 85 fŒmeas restantes,64 pariram. O diagnostico de prenhez por meio da ultra-sonografiatransretal apresentou 35,29% de acurAEcia no 19