The Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera: Chrysomelidae), is a major pest of potato plants worldwide and is notorious for its ability to develop resistance to insecticides. Cry3 toxins synthesized by Bacillus thuringiensis ssp. tenebrionis have been used successfully to manage this pest. Resistance to Cry toxins is a concerning problem for many insect pests; therefore, it is important to determine the mechanisms by which insects acquire resistance to these toxins. Cadherin‐like and ABC transporter proteins have been implicated in the mode of action of Cry toxins as mutations in these genes render lepidopterans resistant to them; however, clear consensus does not exist on whether these proteins also play a role in Cry3 toxin activity and/or development of resistance in coleopterans. In the current study, we identified the L. decemlineata orthologues of the cadherin (LdCAD) and the ABCB transporter (LdABCB1) that have been implicated in the mode of action of Cry toxins in other coleopterans. Suppression of LdABCB1 via RNA interference reduced toxin‐related larval mortality, whereas partial silencing of LdCAD did not. Our results suggest that the ABCB is involved in the mode of action of Cry3Aa toxins; however, no evidence was found to support the role of cadherin as a receptor of Cry3Aa in L. decemlineata.

Entomopathogenic fungi are promising microbial agents for agricultural pests, especially piercing-sucking insects. In this study, eight indigenous fungal isolates including four isolates of Metarhizium brunneum and four isolates of Beauveria bassiana were tested on Orosanga japonica Melichar (Hemiptera: Ricaniidae) in order to find an effective control agent that can be utilised for the development of oil-based fungal mycoinsecticides. In the screening test using 1 Â 10 7 spores ml À1 concentration, KTU-24 (B. bassiana) and KTU-51 (M. brunneum) had the highest lethal activity against nymphs and adults of the target pest. Also, at the highest concentration (10 9 spores ml À1 ), KTU-24 showed 92.33 and 94.88% mortality on nymphs and adults at the dose-response tests, respectively, and the KTU-51 isolate showed 100% mortality on both stages of O. japonica under laboratory conditions. With these results, KTU-24 and KTU-51 isolates were used to develop biopesticides. While the mass production of B. bassiana was carried out with liquid-state fermentation, solid-state fermentation was used for mass production of M. brunneum. Spores of both isolates were formulated in oil, and products were named as RICANICIDAL Bbas-TR61 and RICANICIDAL Met-TR61, respectively. Formulations caused over 97% mortality against nymphs and adults of O. japonica under field conditions and both formulations showed higher efficacy than commercial mycoinsecticides at 10 8 spores/ml concentration 20 days after treatment. The currents study shows that both mycoinsecticide formulations are highly promising for management of O. japonica.

Bacillus thuringiensis (Bt) produces vegetative insecticidal proteins (Vip) during its vegetative growth stage. Vip3 proteins have a significant role in insecticidal activity of this bacterium. Each new bacterial isolate may encode Vip with different significance. The Vip protein coding by vip genes of two Bt strains (BnBt and MnD) with high insecticidal activity was characterized in this study. Polymerase chain reaction (PCR)-based screening for Vip genes of these Bt isolates expressed the detected Vip gene and tested the protein for insecticidal activity against the cotton leafworm, Spodoptera littoralis larvae. As a result of the screening tests, Vip3 genes were determined in MnD and BnBt isolates. Vip3 genes of both isolates were expressed and confirmed by 90 kDa proteins. Partially purified and trypsin-activated protein samples of BnBt and MnD isolates were tested against the second instar larvae of S. littoralis. The results showed that the highest insecticidal activity of the Vip3 proteins of BnBt and MnD was 86.66% and 83.33% mortality in 10 days, respectively. The median lethal concentrations (LC 50) of BnBt and MnD were determined as 41.860 and 55.154 ng/μl, respectively. The results suggest that Vip3 protein is effective for preventing resistance in various insect-pest species. The expressed proteins may be utilized as a biopesticide against nocuous insects.