Flowerlike Mg(OH)2 Cross-Nanosheets for Controlling Cry1Ac Protein Loss: Evaluation of Insecticidal Activity and Biosecurity

Bacillus thuringiensis (Bt) can produce Cry proteins during the sporulation phase, and Cry protein is effective against lepidopteran, coleopteran, and dipteran insects and nematodes. However, Cry protein tends to be discharged into soil and nontarget plants through rainwater runoff, leading to reduced effective period toward target insects. In the present study, nano-Mg(OH)2 (magnesium hydroxide nanoparticles, MHNPs) were synthesized to control the loss of Cry1Ac protein and deliver protein to Helicoverpa armigera (Lepidoptera: Noctuidae). The results showed that Cry1Ac protein could be loaded onto MHNPs through electrostatic adsorption, and both MHNPs and Cry protein were stable during the adsorption process. Meanwhile, the Cry1Ac-loaded MHNPs could remain on the surface of cotton leaves, resulting in enhanced adhesion of Cry1Ac protein by 59.50% and increased pest mortality by 75.00%. Additionally, MHNPs could be slowly decomposed by acid medium and MHNPs showed no obvious influence on cotton, Bt, Escherichia coli, and H. armigera. Therefore, MHNPs could serve as an efficient nanocarrier for delivery of Cry1Ac protein and be used as a potential adjuvant for biopesticide in agricultural applications.