[Activity of neem extract on the embryonary development of Ctenocephalides felis felis (Bouché, 1835) (Siphonaptera: Pulicidae)]. / Atividade do extrato de nim sobre o desenvolvimento embrionário de Ctenocephalides felis felis (Bouché, 1835) (Siphonaptera: Pulicidae).

The present study had as objective to evaluate the activity of limonoid azadiractin, extracted of the seeds of the plant Azadirachta indica, neem, on the embryonary development of Ctenocephalides felis felis. A dog was sprayed with the formulation 10%, another dog was kept as control, without treatment. Both had been infested weekly with 600 fleas, in the ratio of 1:1 between males and females. The deriving positions of the infestations had been incubate per seven days in assay pipes, and evaluated it percentage of emerging of flea eggs, comparing themselves the averages of the groups treat and have controlled. The extract of nim presented activity on the embryonary development of C. f. felis, keeping superior levels of effectiveness 80% until day +14, beyond diminishing the position and inhibiting the development between urging larval of the percentage of larvae that had come out.

Structure of the insect head as revealed by the EN protein pattern in developing embryos.

The structure of the insect head has long been a topic of enjoyable yet endless debate among entomologists. More recently geneticists and molecular biologists trying to better understand the structure of the head of the Dipteran Drosophila melanogaster have joined the discourse extrapolating from what they have learned about Drosophila to insects in general. Here we present the results of an investigation into the structure of the insect head as revealed by the distribution of engrailed related protein (Engrailed) in the insect orders Diptera, Siphonaptera, Orthoptera and Hemiptera. The results of this comparative embryology in conjunction with genetic experiments on Drosophila melanogaster lead us to conclude: (1) The insect head is composed of six Engrailed accumulating segments, four postoral and two preoral. The potential seventh and eighth segments (clypeus or labrum) do not accumulate Engrailed. (2) The structure known as the dorsal ridge is not specific to the Diptera but is homologous to structures found in other insect orders. (3) A part of this structure is a single segment-like entity composed of labial and maxillary segment derivatives which produce the most anterior cuticle capable of taking a dorsal fate. The segments anterior to the maxillary segment produce only ventral structures. (4) As in Drosophila, the process of segmentation of the insect head is fundamentally different from the process of segmentation in the trunk. (5) The pattern of Engrailed accumulation and its presumed role in the specification and development of head segments appears to be highly conserved while its role in other pattern formation events and tissue-specific expression is variable. An overview of the pattern of Engrailed accumulation in developing insect embryos provides a basis for discussion of the generality of the parasegment and the evolution of Engrailed patterns.