Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/27/2005
Publication Date: 7/1/2006
Citation: Mohandass, S., Arthur, F.H., Zhu, K., Throne, J.E. 2006. Hydroprene prolongs development time and increases mortality of eggs of Indianmeal moth (Lepidoptera: Pyralidae). Journal of Economic Entomology 99: 1007-1016. Interpretive Summary: When eggs of the Indian meal moth are laid and when the mature larvae wander to find a food source, they are vulnerable to contact insecticides, which include the insect growth regulator hydroprene However, there is little information regarding the effects of hydroprene on these vulnerable life stages of the Indian meal moth. We exposed eggs and mature larvae on concrete treated with the label rate of hydroprene. Exposure of eggs caused either a delay in hatch rate or egg mortality, depending on how long the eggs were exposed. Similarly, exposure of mature larvae either prevented or delayed adult emergence, depending on the time larvae were exposed. Effects also seemed to increase with temperature. Results show that hydroprene affects the vulnerable life stages of the Indian meal moth and could be used in management programs for stored-product facilities.
Technical Abstract: Eggs of the Indianmeal moth, Plodia interpunctella (Hübner), were exposed to the labeled rate of hydroprene (1.9 X 10-3 mg[AI]/ cm2) sprayed on concreted petri dishes. These eggs were exposed for 1, 3, 6, 12, and 18 h and until hatching (continuous exposure) at temperatures of 16, 20, 24, 28, and 32ºC and 57% relative humidity until the emergence of 1st instars. The development time and egg mortality were significantly influenced by temperature and exposure periods. At 16ºC, hydroprene did not cause differences in development time when eggs were exposed for different periods. At temperatures above 16ºC, the development time was prolonged by increasing exposure periods, and this prolongation decreased with increased temperatures. The longest development time (15.0 + 0.2 d) occurred at 16ºC, and the minimum development time (3.2 + 0.3 d) occurred at 32ºC. Mortality increased when eggs were exposed for longer periods at any of the five temperatures. The greatest mortality (81.6 + 2.1%) occurred when eggs were continuously exposed on treated surfaces at 32ºC. We used development time instead of rate (1/development time) to fit simple linear or polynomial regression models to the development data. Appropriate models for development time and mortality were chosen based upon lack-of-fit tests. The regression models can be used in predictive simulation models for the population dynamics of Indianmeal moth to aid in optimizing use of hydroprene for insect management.