Efeito do nematóide entomopatogênico Steinernema glaseri (Steiner, 1929) (Rhabditida: Steinernematidae) isolado santa rosa sobre os parâmetros biológicos de ninfas ingurgitadas de Amblyomma cajennense (Fabrícius, 1787) (Acari: Ixodidae)

Abstract

Amblyomma cajennense (Fabrícius, 1787) (Acari: Ixodidade) is an ectoparasitic kind of horse, widely distributed in south and central America. The indiscriminate use of acaricidal has taken this animals population to a critical resistence situation to drugs and the exclusive use of acaricidal is just viable in pratical and economical terms became necessary the job of alternative control method. The nematodes entomopathogenic has bem indicated as sucessiful agents to control ticks, however is short the number of the studies about that, the target is analyse the potential os Steinernema glaseri strain Santa Rosa as biological agent control of A. cajennense. The experiment was made in the EMBRAPA GADO DE LEITE, Parasitology Laboratory – Juiz de Fora (MG), between october of 2005 and january of 2006. Has ben tested differents concentrations of S. glaseri (0, 156, 325, 650, 1250, 2500, 5000 e 10000 infectives juveniles (IJ) per tested unity (UT). Each one of this treatment was composed per 10 tested unitys crated with Petri dish sterilized, 4 ml of destil water and 10 nynphs in na total of 100 types for treatament. The Petri dish was closed with parafil and keeped in a humid chamber kind of BOD (27±1ºC and RH>80%) per 72 hours. After that period the engorged nynphs of A. cajennense was washed with destil water and removed to a Petri dish without sand or IJ and observed by each 24±1 hour during 20 days, with the objetive to observe wich alterations in a parametres biological such as: ecdysis period (EP), pre-ecdysis period (PEP), ecdysis percentual (%Ec), and mouthing period (MP). Each parametres was analysed about adults connections, comprising male and female ande for each one of the sex separating by tested unitys as will. The statistic data treatment was maked with Variance Analyse, Tukey- Kramer Test, Kruskal-Wallis and Dunn’s (p 0.05) On the treatment with 5000 IJ/UT happens the significant reduction of PEP totally, such as MP, in connections with control and xv considerating only the males. The MP had soffer the significant reduction too. On the treatment with 10000 IJ/UT had a significant increase of PEP totally and the EP totally was reduced highly expressive in this treatment by connection with control. The male ecdysis period had present a significant increase in four of the seven treatments (treatmments with 156, 612, 2500 and 5000 IJ). The mortality such as the percentual reduction of ecdysis just was significant on the treatment with 10000 IJ/UT. Until without genital hole of A. cajennense nynphs, S. glaseri was able to make the deleterious action in concentration up 5000 IJ/UT. The treatment of 5000 and 10000IJ/UT was deleterious by determined process of no parasitary phase of A. cajennense. However new studyies are necessary, in vitro yet, with superior doses than 10000 IJ/UT, due to confirm the entomopathogenic potential of A. cajennense under de S. glaseri population.