Aphicidal activities of Moroccan Bacillus thuringiensis strains against cotton aphid (Aphis gossypii)

The objective of this study was to evaluate the insecticidal effect of toxins from Moroccan Bacillus thuringiensis strains (Berliner) (Bt) on Aphis gossypii (Homoptera: Aphididae). Aphis gossypii is one of the most pests of Moroccan crops. Their management is based traditionally on using chemical products. Some of them are well known to be potentially toxic to the environment and human health. Therefore, alternative strategies for aphid management in crops have been developed in recent years, including a biological control using toxins of bacterial strains. In this study, the artificial diet bioassay was used to screen the aphicidal effect of 82 Bt toxins against first instar nymphs and third instar nymphs of A. gossypii. Among the examined Bt strains, eleven showed a high insecticide activity against A. gossypii stages. In addition, the assessment of the lethal concentration (LC50) of selected Bt revealed that the local BtA4, BtA1 and Bt21.6 exhibited higher insecticidal activity against first instar nymphs of A. gossypii (LC50 (BtA4)=0.15, LC50 (BtA1)=0.23 and LC50 (Bt21.6)=0.25 mg/ml) and the selected strains BtB6, BtA10 and Bt21.6 exhibited the relatively best activity third instar nymphs of A. gossypii (LC50 (BtB6)= 0.48, LC50 (BtA10)= 0.79 and LC50 (Bt21.6)= 1.14 mg/ml) of A. gossypii. Therefore, the results of this study indicate that the selected B. thuringiensis strains have great potential to be used in the integrated A. gossypii management.

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Aphicidal activity of Bacillus thuringiensis strain AH‐2 against cotton aphid ( Aphis gossypii )

Entomological Research ◽

10.1111/1748-5967.12481 ◽

2020 ◽

Author(s):

Henry B. Ajuna ◽

Iksoo Kim ◽

Yeon Soo Han ◽

Chaw Ei Htwe Maung ◽

Kil Yong Kim

Keyword(s):

Bacillus Thuringiensis ◽

Aphis Gossypii ◽

Cotton Aphid ◽

Aphicidal Activity ◽

Thuringiensis Strain

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Selection of Bacillus thuringiensis Strains Toxic Against Cotton Aphid, Aphis gossypii Glover (Hemiptera: Aphididae)

BioAssay ◽

10.14295/ba.v5.0.70 ◽

2010 ◽

Vol 5 (0) ◽

Cited By ~ 1

Author(s):

Rose Gomes Monnerat ◽

Viviane Melatti ◽

Lílian Praça ◽

Érica Martins ◽

Edison Sujii ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Aphis Gossypii ◽

Cotton Aphid ◽

Aphis Gossypii Glover ◽

Selection Of

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Study on using gamma radiation to inactivate Bacillus thuringiensis spores in biopesticide

Nuclear Science and Technology ◽

10.53747/jnst.v7i1.118 ◽

2021 ◽

Vol 7 (1) ◽

pp. 43-48

Author(s):

Thi Thom Nguyen ◽

Van Binh Nguyen ◽

Bang Diep Tran ◽

Dang Sang Hoang ◽

Xuan An Tran ◽

...

Keyword(s):

Bacillus Thuringiensis ◽

Gamma Radiation ◽

Insecticidal Activity ◽

Animal Health ◽

Heliothis Armigera ◽

Optimal Dose ◽

Living Cells ◽

Soil Microflora ◽

Insecticidal Effect ◽

Bt Toxins

Bacillus thuringiensis (Bt) produces different types of toxin that have potent and specific insecticidal activity. In recent years, Bt toxins have been used as the safe biological control agents to protect crops replacing for chemical insecticides. Bt-based biopesticides that have been commercialized as the alternative products to control pests and insects for sustainable agriculture, contain toxicity crystals and a significant number of spores that affects to the soil microflora. These uncontrollable changes may contaminate the cultivation soil, and eventually cause adverse effects to human and animal health. Therefore, the living cells and spores existing in the Bt-biopesticides should be controlled. This study evaluates the effects of gamma radiation on spore viability, germination and growth of the existing spores after spraying on the soil and the insecticidal effectiveness of a Bt-based biopesticide (VBT) against lepidoptera larvae. We attempted to identify the optimal dose that couldinactivate Bt spores but the toxicity of Bt still retain highly. The results revealed that the dose of 20 kGy is enough to control all living cells and spores in the product that consists of approximately 5.2 × 107 spores in the initial VBT. Though the growth of existing spores after spraying on the soil reduced by 85% or more by irradiation, their insecticidal activity against Heliothis armigera larvae reduced by 20-30% only as compared to that of the initial VBT. It suggested that gamma irradiation can be applied as useful way to control the living cells and spores existing in the commercial Bt-based bio-pesticides, and the radiation dose of 20 kGy is enough to kill all spores in VBT, but still kept its insecticidal effect for Heliothis armigera larvae

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