Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 22, 2005
Publication Date: October 1, 2005
Citation: Zhu, Y., Adamczyk Jr, J.J., West, S.J. 2005. Avidin, a potential bio-pesticide and synergist to bacillus thuringiensis berliner toxins against field crop insects. Journal of Economic Entomology. 98:1566-1571. Interpretive Summary: To prolong the benefit of Bt cotton biotechnology, alternative control measures should be developed to relieve selection pressure and slow down Bt resistance development among many lepidopteran insects. Ideally, control measures would also work on insects with sucking mouthparts, such as plant bugs and cotton aphids. Avidin is a bioactive glycoprotein found naturally in the white of bird, reptile, and amphibian eggs. Avidin has a very strong affinity for the vitamin biotin, but it is safe to high animals. In this study, we found that growth of all five lepidopteran insects was greatly retarded by diet which contained avidin. Avidin in diet at 40 ppm or greater killed up to 100% of the larvae that fed on it. We also found that avidin synergized Bt toxicity against the bollworm. Avidin is a bioactive protein, and its gene could be inserted into cotton genomes alone or stacked with Bt genes. By targeting different sites, avidin has potential to be effective against insects with sucking mouthparts. Its introduction into transgenic cotton for control wide range of pests, along with its synergistic action with Bt toxins could be a major advance in cotton insect control.
Technical Abstract: Artificial diet was supplemented with avidin at 10 and 100 ppm to determine its effects on growth and mortality of five lepidopteran insects: Helicoverpa zea, Heliothis virescens, Spodoptera frugiperda, Spodoptera exigua, and Anticarsia gemmatalis. All insects were placed on diet immediately after hatching and observed until death or pupation occurred. At a concentration of 10 ppm, avidin had little or no effect on growth and mortality as compared with the control. However, at a concentration of 100 ppm, mortality of all tested insects was approximate 100%. H. zea was further tested by adding a sub-lethal concentration of Bt (Bacillus thuringiensis) with 10ppm avidin in diet. The synergistic effect was significant, and the mortality rate was increased by up to 57% on the Bt+avidin diet.