Toxinas inseticidas de Bacillus thuringiensis

Abstract

Produzir alimentos com qualidade e em quantidade suficiente para atender ao crescimento populacional tornou-se um dos maiores desafios da humanidade. Essa meta exige o desenvolvimento de tecnologias racionais que otimizem o uso de recursos naturais, ampliando a capacidade produtiva, além de estratégias para redução das perdas de produção.Insetos, fungos, vírus e bactérias causam severas perdas à produção de alimentos em todo o mundo, e ainda hoje o controle desses agentes é comumente realizado através de defensivos sintéticos. Algumas das moléculas utilizadas no controle de insetos-praga são extremamente tóxicas para organismos não alvo e seu uso incorreto, em muitos casos, é prejudicial à saúde dos animais e seres humanos, induzindo doenças importantes, como câncer e males do sistema imunológico. Além disso, alguns desses compostos são persistentes, sendo degradados lentamente e levando à poluição do solo e da água. A evolução de populações de insetos resistentes a moléculas sintéticas

Bioactivity of Bacillus thuringiensis (Bacillales: Bacillaceae) on Diatraea saccharalis (Lepidoptera: Crambidae) eggs

“…Activated toxins connected to membrane receptors (ALP and APN) present in the columnar cells of the D. saccharalis midgut lead to cell death and probably embryonic death 83–85 . However, it is proposed that Bt toxins can act in two different ways: (i) in their active form, the toxins associate with specific receptors present in the apical membranes of susceptible cells, and (ii) in their inactive form, toxins have the potential to bind to receptors, exhibiting higher toxicity than that of toxins in their active form 21 …”

“…In their active form, the toxins exhibit affinity for receptors present on specific cells in susceptible organisms (e.g. coleopterans, dipterans and lepidopterans) 14,21 …”

“…coleopterans, dipterans and lepidopterans). 14,21 The application of Bt to insect eggs may lead to mortality; however, this phenomenon has not been studied extensively. 22 Considering that D. saccharalis is one of the major pests affecting sugarcane cultivation, 23 utilizing Bt to target eggs in addition to larvae, may be useful in obtaining enhanced control of this insect pest.…”

Possible interference of Bacillus thuringiensis in the survival and behavior of Africanized honey bees (Apis mellifera)

“…kurstaki , containing the proteins Cry1Aa, Cry1Ab, Cry1Ac, Cry2Aa, and Cry1Ac, whereas Xentari is formulated from B. thuringiensis var. aizawai , which produces Cry1Aa, Cry1B, Cry1Ca, and Cry1Da 40 which may be one factor related to the differences observed in the flight capacity of 24-h-old worker bees. When Cry1Ba was present in A. mellifera feed, no changes were observed in survival time 30 , 41 , consumption of the food 41 , flight 30 or time of flight 30 .…”

Bioprospecting of Bacillus thuringiensis in the control of Aedes aegypti larvae

“…Β-exotocin (thuringiensin) is thermostable, acting by inhibiting nucleases, inhibiting RNA synthesis in cells and can cause lesions in tissues of mice and chickens, causing mutations in mammalian physiological systems, making their use controlled or even prohibited in some countries (Horta et al, 2017).…”