Effect of methyl bromide on the embryonic development of Acarus siro L. (Acarina: Acaridae)

Abstract

The first mitotic divisions of the fertilized egg of Acarus siro occur within the female's reproductive system. The egg is laid at the time of the formation of the germ band. The integument of the methyl bromide-treated egg became non-elastic, sticky and soft. Yolk globules of eggs treated before cleavage occurred had completely disintegrated. At segmentation of the embryo the fumigant caused some abnormalities in the size of egg rudiments and in the depth of furrows separating segments. Changes in the developing nervous system were also evident. Three periods of sensitivity were distinguished in eggs fumigated with methyl bromide (1) Before the start of gastrulation movements in the germ band; (2) The formation of the central nervous system; (3) The period preceding dorsal closure. The possible mechanisms of sensitive periods to methyl bromide in the embryonic development of Acarus siro L. are discussed.