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

Aedes mosquitoes are known to be infected by arboviruses causing disease such as dengue, zika fever, and chikunguya fever, and subsequently transmit them, to humans through the bite of infected females. Chemical control is a measure adopted as part of sustainable management and integrated vector control for public health. There are four principal classes of insecticides used for controlling mosquitoes, all being neurotoxic: organochlorides, organophosphates, carbamates, and pyrethroids. The objective of this work was to review reports on the environmental effects of the insecticides most commonly used for controlling Ae. aegypti. This bibliographic study was conducted using articles and books available in the literature with no time restriction. The databases accessed were: Google Scholar, Pubmed, SciELO, and ScienceDirect. These insecticides exhibit toxicity to the environment, and may accumulate in food and water and in the body of vertebrates. Resistance to different insecticides is a problem when the mode of control is chemical, because insects survive insecticide application and higher doses are necessary for controlling the vectors. Considering these results, the ideal method would be the newly proposed means of mosquitoes control using technology related to modern biotechnology.

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Sitophilus zeamais Motschulsky, 1855 (Coleoptera: Curculionidae) which develops inside the grain, is an aggressive pest of stored grains. Here, we evaluated the efficiency of diatomaceous earth (DE), Diatomita CI/325 CX, and dolomite (DOL), Dolomita Dr. Kanyo, against S. zeamais reared on corn under laboratory conditions and observed external alterations on treated insects using scanning electron microscopy (SEM). Insects treated with both DE and DOL were impregnated with particles on the body surface, and they showed 100% mortality after 10 days of exposure. Damages caused by inert dusts may have contributed to dehydration and desiccation, consequently, leading insects to death. Thus, diatomaceous and dolomite were effective against S. zeamais under laboratory conditions.

Chemical pesticides tend to accumulate in soil, resulting in human and environmental health risks. Hence, alternative methodologies involving chemical pesticides are beneficial for the control of agricultural pests. Metarhizium anisopliae is an entomopathogenic fungus that acts on different developmental stages of pest insects such as Diatraea saccharalis, a holometabolic lepidopteran with high potential for infestation in sugarcane crops. The present study evaluated the biocontrol effect of M. anisopliae isolates MT and E9 on D. saccharalis eggs at different ages by investigating the external and internal morphological alterations in treated eggs. Conidial suspensions of M. anisopliae isolated from MT and E9 at concentrations of 10 7 conidia/mL were applied to eggs of D. saccharalis aged 0, 24, 48, 72, 96 and 120 h. The eggs were observed every 24 h during development (0 h to 144 h). Samples were collected for observational, histological, and ultrastructural analyses. We found that the MT isolate caused 100% inviability of eggs aged 0 -72 h, 144 h after the bioassays, while the effect of the E9 isolate varied between 49.40% and 93.75%. Melanization was observed on the periphery of the eggs 24 h after the bioassays. Fungal hyphae developed 48 h after bioassays, crossed the egg chorion, and dispersed through the yolk region, inhibiting embryonic development. After 72 h, hyphae and conidiophores were observed on the eggs, which persisted for 144 h. In sum, M. anisopliae MT isolate can be used as a biological controller for D. saccharalis eggs.

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Chromobacterium subtsugae é uma bactéria gram-negativa que vem sendo utilizada na agricultura, nos últimos anos, no manejo de diversas espécies de artrópodes-pragas, devido aos seus metabólitos tóxicos. Apesar de avanços na sua utilização, são escassas as informações acerca de sua patogenicidade no Brasil. Desse modo, a presente revisão bibliográfica objetiva compilar os dados mais recentes (2011-2021) sobre as características gerais de C. subtsugae, seu modo de ação e os resultados no manejo biológico de diferentes artrópodes-praga. O levantamento bibliográfico foi realizado nas plataformas Google Scholar, Periódicos Capes e Science Direct, com um filtro para o período de 2011-2021, utilizando a combinação de palavras: Chromobacterium subtsugae, bactéria entomopatogênica (entomopathogenic bacteria) e controle biológico (biological control). C. subtsugae evidencia vários efeitos em insetos-praga como toxicidade oral, repelência, redução da fecundidade em fêmeas e oviposição e, inibição da alimentação em indivíduos das ordens Hemiptera, Thysanoptera, Coleoptera, Diptera e Acari (ácaros fitófagos), sendo seu mecanismo de ação considerado complexo, podendo sintetizar no decurso da fermentação, três fatores inseticidas: cromamida A, violaceína e um composto não identificado. Perante tais elucidações, constata-se a importância da referida bactéria no desenvolvimento de novos produtos direcionados ao manejo de diversos insetos-praga, principalmente, pelo seu amplo espectro de ação. Ademais, espera-se que os dados levantados sirvam de referencial para pesquisas futuras com C. subtsugae, tanto em experimentos em campo quanto laboratoriais no Brasil, posto que não há inseticida comercial contendo a referida bactéria como ingrediente ativo.

Os insetos apresentam a maior biodiversidade entre a classe Animal e são fontes ricas de produtos biotecnológicos. Espécies da família Calliphoridae (Diptera) apresentam hábitos necrófagos durante a fase larval, assim são expostas a diferentes microrganismos, produzindo peptídeos antimicrobianos (AMPs) como sistema de defesa. O objetivo deste trabalho foi realizar um levantamento bibliográfico dos principais peptídeos antimicrobianos identificados em Calliphoridae (Diptera), fornecendo dados para a bioprospecção de novos compostos. A revisão bibliográfica foi realizada nas plataformas: Google Acadêmico e SciFinder e foram selecionados 56 artigos para o desenvolvimento deste trabalho. Os AMPs possuem atividade contra amplo espectro de bactérias gram-positivas e gram-negativas, por isso apresentam grande interesse para tratamentos de feridas (e.g.: Terapia Larval) e bioprospecção de novos antibióticos. Estas moléculas são obtidas a partir do produto de excreção e secreção das larvas de Calliphoridae e sua ação tem como alvo primário a membrana celular das bactérias, devido interações eletroestáticas e interações de van der Waals com a membrana lipídica. A utilização de técnicas de separação acopladas com espectrometria de massas permitiu a identificação e caracterização de peptídeos da classe Defensina em diferentes espécies de califorídeos. A bioprospecção de novas moléculas antimicrobianas em moscas é uma área promissora dentro da biotecnologia, devido ao aumento do número de bactérias resistentes aos antibióticos atuais.