Franklin M. Cunha

Histological description of the midgut and the pyloric valve of Tropidacris collaris (Stoll, 1813) (Orthopetera: Romaleidae)

The present research describes the histology of the midgut, gastric caeca, and pyloric valve of Tropidacris collaris (Stoll, 1813), (Orthopetera: Romaleidae). We used light microscopy, staining (Gomoris trichrome and periodic acid-Schiff (PAS)), and a routine histological analysis method (hematoxilin-eosin). The insects were obtained from, and also bred in, the Laboratory of Entomology, Department of Biology, of the Rural Federal University of Pernambuco (UFRPE). The collected material was fixed in alcoholic Botüin and embedded in paraplast. The results demonstrated that the midgut wall is composed of an inner epithelial layer and two outer layers of striate muscles: one internal (circular) and the other external (longitudinal), with connective tissue between the muscle fibers. The epithelium is single-layered, with two cell types: regenerative and elongated columnar. The gastric caeca presents muscle layers similar to those of the midgut. Simple columnar epithelium lines the gastric caeca, which presents villi and projects towards the lumen. The pyloric valve is of striate muscle tissue, covered by a single epithelial-cell layer.

Bioactivity of Piper hispidinervum (Piperales: Piperaceae) and Syzygium aromaticum (Myrtales: Myrtaceae) Oils, with or without Formulated Bta on the Biology and Immunology of Spodoptera frugiperda (Lepidoptera: Noctuidae)

ABSTRACT The combination of essential oils and Bacillus thuringiensis Berliner may represent an interesting control strategy. Thus, the study tested the following hypothesis: the combination of long pepper oil (Piper hispidinervum L.) and clove (Syzygium aromaticum L.) oils in two concentrations with Xentari WG (Bta) yields a more effective control of Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) affecting biological and reproductive parameters and leading to changes in the levels of phenoloxidase and nitric oxide in the hemolymph of the pest. The results demonstrate that only long pepper oil, at the highest concentration with Xentari WG (Bta), promotes reduced larval survival. However, both oils with or without the insecticide interfere in the biology and humoral immunity of S. frugiperda. All treatments caused a decrease in the amount of eggs, except for the clove oil at both concentrations without Bta. Therefore, the use of these oils is a promising alternative for the integrated management of S. frugiperda; however, its association with Bta demonstrated no significant increase in their efficiency.

Patogenicidade de Metarhizium anisopliae var. anisopliae e Metarhizium anisopliae var. acridum sobre Nasutitermes coxipoensis (Holmgren) (Isoptera: Termitidae)

A acao de Metarhizium anisopliae var. anisopliae e Metarhizium anisopliae var. acridum sobre o cupim de monticulo Nasutitermes coxipoensis (Holmgren) e a producao de conidios sobre os insetos mortos foram estudadas em laboratorio. Doses infectivas foram determinadas atraves do contato direto dos insetos com a cultura fungica apos 12 dias de crescimento e quantificacao dos conidios em câmara de Neubauer. Foram utilizadas as doses 0,5 x 106 e 1,6 x 107 conidos/ml, para M. anisopliae var. anisopliae, e 1,4 x 105 e 1,8 x 106 conidios/ml para M. anisopliae var. acridum, nominadas dose A e dose B, respectivamente. As doses corresponderam a 3 min. e 15 min. de contato direto de 20 cupins com a cultura fungica. A producao de conidios foi avaliada utilizando-se insetos inoculados com o fungo, 10 dias apos a morte. Os bioensaios foram realizados em triplicata. Os percentuais de mortalidade acumulada de N. coxipoensis tratados com M. anisopliae, no terceiro dia apos a inoculacao, foram: controle, 15,7%; dose A 95,7% e dose B 100%; para M. anisopliae var. acridum foram: controle, 13,3%; dose A 66,4 e dose B 88,8%. A media da producao de conidios foi mais elevada para M. anisopliae var. anisopliae do que para M. anisopliae var. acridum. Os resultados mostraram que M. anisopliae var. anisopliae apresentou maior potencial para o controle biologico de N. coxipoensis.

Histological and Histochemical Changes by Clove Essential Oil Upon the Gonads of Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae)

Spodoptera frugiperda es un insecto polifago que causa perdidas economicas a varias cosechas en Brasil y es el mayor obstaculo para la produccion de maiz. Este estudio esta centrado en el control alternativo, con productos botanicos que se estan expandiendo y ofrecen una amplia variedad de moleculas que interfieren con diferentes parametros biologicos de plagas de insectos. Por tanto, se puso a prueba la hipotesis de que el aceite esencial de clavo de olor afecta la espermatogenesis. La histoquimica de los ovarioles y la fertilidad de S. frugiperda. Los resultados mostraron que el aceite esencial de clavo de olor afecta la gametogenesis de los ovarioles en S. frugiperda, lo que incide negativamente en su reproduccion, demostrando ser una herramienta prometedora para el control de esta plaga.

Impact of Bt cotton on the immune system and histology of the midgut of the fall armyworm Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae)

Despite the efficiency of transgenic plants expressing Bacillus thuringiensis (Bt) toxins as insecticides against several lepidopterans, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) is one species that presents low susceptibility to most Bt crops. This study investigated the effects of the Cry1Ac toxin expressed by Bt cotton in the midgut of S. frugiperda and its effects on the humoral and cellular immune responses. Three hypotheses were proposed and tested with contributing factors for the natural tolerance of S. frugiperda: (i) midgut regenerative cells are activated by the Cry1Ac toxin, and thus renew the epithelial cells damaged by the protein, (ii) Cry1Ac increased production of nitric oxide or phenoloxidase in the hemolymph, and (iii) there are qualitative and quantitative variations in the hemocyte levels of S. frugiperda. Caterpillars were reared using Bt cotton (Acala 90B) and non-Bt isolines (Acala 90), from the first to the fourth instar. The Bt cotton promoted elongation of the epithelial cells in the midgut of S. frugiperda caterpillars. Hence, evidence only supported the hypothesised increase of phenoloxidase (ii) and qualitative and quantitative differences in hemocyte levels (iii) in insects that were fed with Bt and non-Bt cotton. These parameters seem to explain the low susceptibility of S. frugiperda to Cry1Ac toxin and they are a viable set of responses for the evaluation of other xenobiotic factors.

Ultrastructure and histochemistry of the fat body of Anthonomus grandis (Coleoptera: Curculionidae)

Abstract Metabolic demands such as growth and reproduction of insects relate directly to the fat body. This organ is responsible for the biosynthesis and storage of nutrients, and participates in the neutralization and detoxification of xenobiotics. Studies show a relationship between its ability to accumulate nutrients and activities, such as diapause and reproduction in the beetle Anthonomus grandis, an important pest of cotton plants. However, there are no detailed studies on the structure and histochemistry of the fat body in this insect. We describe the ultrastructure and histochemistry of the fat body in A. grandis and discuss some of its characteristic features. The fat body is composed of a single cell type, the trophocyte, which is a voluminous cell with a spherical or bilobed nucleus, and cytoplasm containing several lipid droplets, glycogen granules (electron-dense), and protein granules. These trophocytes have few areas of contact with each other and form lobes, enclosed by connective tissue. A high metabolic activity of the fat body is deduced by the intense histochemical staining for protein and polysaccharide compounds, demonstrating that specific processes, such as the synthesis and secretion of vitellogenin, could be a target for more specific studies on methods to control this insect.

Morphological and histological characterization of production structures, storage and distribution of venom in the parasitic wasp Bracon vulgaris

It was described the morphology and histological composition of the structures related to production, storage and distribution of Bracon vulgaris venom, a wasp that parasite their hosts after the inoculation of a venom which causes irreversible paralysis. Were found 22 glandular filaments, coated with secretory epithelium associated with a reservoir coated internally by a chitin layer and externally by striated muscular fibers. A valve mediates the passage of the toxin to venom duct towards the parasitoids sting.