Submitted to: Journal of Economic Entomology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/29/2012
Publication Date: 6/29/2012
Citation: Higbee, B.S., Siegel, J.P. 2012. Field Efficacy and Application Timing of Methoxyfenozide, a Reduced-risk Treatment for Control of Navel Orangeworm (Lepidoptera: Pyralidae) in Almond. Journal of Economic Entomology. 105(5): 1702-1711. Interpretive Summary: There is considerable interest in replacing broad spectrum insecticides, such as the organophosphates, with more selective insecticides such as the insect growth regulator methoxyfenozide. In addition growers and their pest control advisers recognize a need for research to be conducted on optimizing the timing of these new insecticides. In this paper we report the results of a two year field study on the efficacy of several insecticides, optimal timing of the application of these chemicals, their ability to kill the eggs of the navel orangeworm, and their impact on three secondary lepidopteran pests of almonds. In these trials a spring application combined with an application made 14 days after the almond hulls split, was as effective as an application made immediately at hull split and followed by an application two weeks later. This finding has implication for control of navel orangeworm in high pressure areas, because it suggests that reducing the offspring of the overwintering flight combined with targeting a flight occurring 1-2 generations later may be as effective as bracketing the nuts with insecticide when they are most vulnerable. Our trials demonstrate that this selective insecticide Intrepid, which kills larvae when they molt, is effective and is a valid replacement for organophosphate insecticides. Improving insect control will improve the quality of the almond crop and replacing broad spectrum insecticides with selective insecticides benefits the environment.
Technical Abstract: Large-scale field efficacy trials of methoxyfenozide (Intrepid®), a reduced risk molting agonist insecticide, were conducted in 2004 and 2005 in an orchard containing ‘Nonpareil’ and ‘Sonora’ variety almonds located in Kern County, California. Methoxyfenozide applied one to three times, and the organophosphate phosmet (Imidan®), alone or in combination with the pyrethroid permethrin (Perm-Up®), were tested for efficacy against navel orangeworm and three other lepidopteran pests of almond, the oriental fruit moth, oblique banded leafroller and peach twig borer. Two or three applications of methoxyfenozide (bracketing hull split or spring plus bracketing hull split) were more effective than a single hull split application of phosmet, phosmet combined with permethrin, or methoxyfenozide. In these trials a spring application followed by a post hull-split application was as effective as the applications bracketing hull split. Navel orangeworm accounted for more than 60% of the total damage and its damage had the strongest correlation with oriental fruit moth damage. In experiments conducted in 2010 to assess the direct toxicity of methoxyfenozide to navel orangeworm eggs under field conditions, exposure to methoxyfenozide reduced survival by 96-99%. We conclude that this reduced risk insecticide is effective, although its efficacy is maximized when applied early.