No abstract

Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) is one of the most aggressive pests of stored grains, causing significant decrease in the nutritional quality of the grains and major losses in economic trade. The ability of this pest to damage grains and other products is directly related to the morphology of the alimentary canal. Considering the importance of the foregut in the digestion, this study aimed to describe the morphology of the crop and proventriculus in S. zeamais adults. The tissues were isolated, processed, and analyzed by using light microscopy, scanning electron microscopy, and transmission electron microscopy. The crop functioned as a storage organ, and its cells showed functional characteristics related to protein synthesis. High densities of prokaryotic microorganisms and spicules were found in the lumen. The proventriculus exhibited eight chitinous teeth, which were responsible for grinding and filtering food particles. This organ formed the stomodeal valve, which controlled the unidirectional flow of food through the alimentary canal. The alimentary canal is the primary surface of contact between the external environment and an insect's internal environment, and knowledge of its morphology is required to better understand the physiology of stored-grain insect pests.

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To evaluate the toxic effect of commercial formulations of neem oil, Azadirachta indica A. Juss, pre-pupae (PP), young pupae (YP) and old pupae (OP) of Diatraea saccharalis F. (Lepidoptera: Crambidae) were sprayed with the diluted extract in distilled water at concentrations of 0.0, 0.3, 0.5, 1.0 and 2.0%. The neem extract caused concentration-dependent effects on mortality of pupae, and the pupae that failed to emerge in adults had multiple abnormalities. The longevity of pupae that emerged in adults (YP and OP group) did not differ from the control group. The abnormalities found in adults were related to mortality in all treatments, except at the concentration of 1.0%. Fertility was assessed according to the oviposition of adult females from the YP group that showed no abnormalities, through the evaluation of the number of deposited eggs and the rate of undeveloped eggs. The results showed a reduction in the number of eggs laid and an increase in the percentage of undeveloped eggs. These results show that neem oil has a high potential to control the toughest stage of the sugarcane borer and also reduces the further development. Therefore, commercial formulations of neem oil have a toxic effect on pupae and adults of D. saccharalis.

Tribolium castaneum Herbst 1797 (Coleoptera: Tenebrionidae), an important pest of stored grains and byproducts, is naturally infected by Gregarina cuneata Stein 1848 (Apicomplexa: Gregarinidae). Changes in the life cycle of insects caused by the parasite development in the midgut were studied. Trophozoites, gamonts (solitary and associated), and gametocysts were present in the midgut of the insects. In young trophozoites, the apical region differentiated into an epimerite that firmly attached the parasite to the host epithelial cells. With maturation, trophozoites developed in gamonts that were associated with the initiation of sexual reproduction in the cell cycle, culminating in the formation of the spherical gametocyst. Morpho-functional analyses indicated that gregarines absorb nutrients from infected cells and can occlude the midgut as they develop. Consequently, nutritional depletion may interfere with the host's physiology, causing decreased growth, delayed development, and high mortality rates of the parasitized insects. These results suggest G. cuneata could be an important biological agent for controlling T. castaneum in integrated pest management programs.

The anatomy and histology of the Malpighian tubules of Diatraea saccharalis larvae have been studied by stereoscope, light and scanning electron microscopy. Tubules lie between hindgut and mid-midgut; and may be subdivided into proximal, middle and distal region. Two ampullae inserted laterally before the pylorus show 2 tubules derived from each. One tubule bifurcates into 2 in the third abdominal segment; these loop backward to the hindgut to form the cryptonephridial system. Whereas larvae have 6 complete tubules, 3 on each side, histological analysis reveals 1 layer containing 2 cells, forming the lumen, microvilli at the top of cells, tracheae and tracheoles, and crystals in the tubule lumen, mainly in the middle and distal regions.

BACKGROUND Bacillus thuringiensis (Bt) is a Gram‐positive bacterium that synthesizes specific protein toxins, which can be exploited for control of various insect pests, including Diatraea saccharalis, a lepidopteran that severely damages sugarcane crops. Although studies have described the effects of Bt in the larval phases of D. saccharalis, few have examined its effect on insect eggs. Herein, we studied the entomopathogenic potential of Bacillus thuringiensis serovar Aizawai GC‐91 (Bta) during D. saccharalis embryo development with the aim of understanding the entomopathogenic mechanism and developing new biological control techniques for target insects. RESULTS Bta concentrations of 5, 10 and 20 g L–1 demonstrated the strongest bioactivity, reducing D. saccharalis egg viability by 28.69%, 33.91% and 34.98%, respectively. The lethal concentrations (LCs) were estimated as: LC50 = 28.07 g L–1 (CI 95% = 1.89–2.38) and LC90 = 65.36 g L–1 (CI 95% = 4.19–5.26). Alterations in egg coloration, melanization and granule accumulation were observed at 24 h, persisting until 144 h. The embryo digestive systems were severely damaged, including narrowing of the intestinal lumen, vesiculations and degenerated cells, causing embryonic death. CONCLUSION The toxicity caused by Bta in D. saccharalis embryos demonstrated its potential as a biological control agent and as a sustainable alternative for integrated management of D. saccharalis infestation. © 2020 Society of Chemical Industry

Introdução: Microplásticos (MPCs) são fragmentos plásticos menores do que 5mm de diâmetro. Eles podem ser formados pela indústria (MPCs primários) ou de detritos gerados a partir dos macroplásticos (MPCs secundários). Objetivo: Essa revisão objetiva explorar a disponibilidade e os danos dos MCPs no ambiente, nos seres vivos e principalmente na saúde humana. Metodologia: Coleta de dados foi realizada no período de Outubro a Dezembro de 2017, nas bases eletrônicas: Scielo, Pubmed, Science Direct, Periódicos CAPES e Google Acadêmico, publicadas no período de 2008 à 2018. Resultados: Nos últimos anos essas partículas tiveram um aumento significativo no ambiente, conduzindo os estudiosos a realizarem diversos experimentos com intuito de verificar a abrangência, disponibilidade e impacto dos MPCs no meio-ambiente. Os seres-vivos têm se mostrado suscetíveis à absorção de MPCs, levando ao acúmulo destas partículas plásticas ao longo da cadeia alimentar podendo gerar consequências no ambiente. Várias pesquisas têm sido desenvolvidas em animais, entretanto, em humanos há uma grande escassez de trabalhos, necessitando de análises que visam entender a interação entre MPCs e o ser humano. Devido à dimensão que os MPCs alcançaram, alguns países criaram leis que proibiram o uso das microesferas em cosméticos. Conclusão: O Brasil ainda não possui leis que limitem o uso de microplásticos pelas indústrias e nem alternativas para a retirada desses fragmentos pelo tratamento da água, visto que eles já estão presentes nas águas brasileiras, assim é necessário o desenvolvimento de políticas públicas e alternativas sustentáveis para este problema.