ABSTRACT
Hyphantria cunea is one of the most important pest insects causing significant damage in many plant species. The present study aimed to evaluate the insecticidal activity of Turkey isolates of Beauveria bassiana and Metarhizium anisopliae against H. cunea larvae under laboratory and field conditions. B. bassiana isolates YK16, YK23 and YK26, and M. anisopliae isolates YK41 and YK45 were sprayed onto the larvae of H. cunea at the respective doses of 1x105 and 1x106 conidia mL-1 and monitored for seven days. Fungal isolates, bio-insecticide Bacillus thuringiensis and chemical insecticide diflubenzuron were used in field studies. Trials were carried out in five replications. All B. bassiana isolates caused 100% mortality on first instar larvae in laboratory trials. Mortality ratios ranged from 100 to 96% on second instar larvae. M. anisopliae isolates YK45 and YK41 caused 88 and 84%, and 81.33 and 77.11% mortalities for the first and second instar larvae, respectively. The mortality rates fluctuated between 91.78-72.89% for B. bassiana on third instar larvae in laboratory conditions. However, M. anisopliae isolates YK45 and YK41 caused 77.11 and 60.22% mortality on third instar larvae, respectively. In the field trials, B. bassiana YK23 displayed promising insecticidal activity with 80.60% mortality on second instar larvae of H. cunea. Other isolates as well caused mortalities ranging from 60.77 to 49.55%. The results revealed that some isolates of B. bassiana and M. anisopliae have potential to control H. cunea larvae. However, additional detailed studies need to be carried out to increase their effectiveness in field conditions.
Subject(s)
Insect Control , InsecticidesABSTRACT
ABSTRACT In this study, the cry1Ab gene of previously characterized and Lepidoptera-, Diptera-, and Coleoptera-active Bacillus thuringiensis SY49-1 strain was cloned, expressed and individually tested on Ephestia kuehniella (Lepidoptera: Pyralidae) and Plodia interpunctella (Lepidoptera: Pyralidae) larvae. pET-cry1Ab plasmids were constructed by ligating the cry1Ab into pET28a (+) expression vector. Constructed plasmids were transferred to an Escherichia coli BL21 (DE3) strain rendered competent with CaCl2. Isopropyl β-D-1-thiogalactopyranoside was used to induce the expression of cry1Ab in E. coli BL21(DE3), and consequently, ∼130 kDa of Cry1Ab was obtained. Bioassay results indicated that recombinant Cry1Ab at a dose of 1000 µg g-1 caused 40% and 64% mortality on P. interpunctella and E. kuehniella larvae, respectively. However, the mortality rates of Bt SY49-1 strains' spore-crystal mixture at the same dose were observed to be 70% on P. interpunctella and 90% on E. kuehniella larvae. The results indicated that cry1Ab may be considered as a good candidate in transgenic crop production and as an alternative biocontrol agent in controlling stored product moths.