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United States Department of Agriculture

Agricultural Research Service

Title: Season-Long Monitoring of Navel Orangeworm with Female Sex Pheromone and Egg Traps

Authors
item Kuenen, Lodewyk
item Rowe, Heather

Submitted to: Proceedings of International Research Conference on Methyl Bromide Alternatives
Publication Type: Abstract Only
Publication Acceptance Date: September 4, 2003
Publication Date: November 1, 2003
Citation: Kuenen, L.P., Rowe, H.C. 2003. Season-long monitoring of navel orangeworm with female sex pheromone and egg traps. Proceedings of International Research Conference on Methyl Bromide Alternatives. November 3-6, 2003, San Diego, California. Paper No. 78.

Interpretive Summary: We monitored the season-long presence of navel orangeworm (NOW) in four almond orchards, a fig orchard and a pistachio orchard in order to begin to understand the prevalence of NOW in relation to these crops in California, USA. We used female-derived sex pheromone (caged unmated NOW females) and egg traps. Egg traps have long been used to monitor NOW egg laying activity; however, trap efficiency is reduced or nil when new hosts become susceptible to infestation by NOW. Pheromone trapping is not normally used for NOW monitoring because no effective synthetic is currently known. Most strikingly, capture of male NOW adults occurred continuously from late March, throughout the growing season and into fall well after harvest. Males were present all season. Capture of eggs, an indicator of female presence and oviposition activity, only sporadically indicated high levels of female presence/oviposition activity. Egg numbers on egg traps are typically high only in spring before new hosts are available and again after harvest when populations are typically higher and fewer new hosts are available. This makes the use of egg traps primarily an adjunct to direct monitoring of hosts. The use of pheromone traps should be of greater predictive value. In the spring, in orchards where high numbers of NOW were present, only 2-3 weeks elapsed as male trap capture increased from zero to >50 males per trap. This was observed consistently during three years of early season trapping with pheromone (unmated females). By contrast, numbers of NOW eggs laid on egg traps increased slowly or were very low all season. As the season progressed there was no apparent concordance between egg counts and numbers of males captured in pheromone traps. We are conducting collaborative projects to identify an active NOW sex pheromone blend and develop better female attractants. Success will allow us to develop improved NOW monitoring programs. Also, easy-to-use attractants may serve as an adjunct or replacement for current control practices.

Technical Abstract: We monitored the season-long presence of navel orangeworm (NOW) in four almond orchards, a fig orchard and a pistachio orchard in order to begin to understand the prevalence of NOW in relation to these crops in California, USA. We used female-derived sex pheromone (caged unmated NOW females) and egg traps. Egg traps have long been used to monitor NOW egg laying activity; however, trap efficiency is reduced or nil when new hosts become susceptible to infestation by NOW. Pheromone trapping is not normally used for NOW monitoring because no effective synthetic is currently known. Most strikingly, capture of male NOW adults occurred continuously from late March, throughout the growing season and into fall well after harvest. Males were present all season. Capture of eggs, an indicator of female presence and oviposition activity, only sporadically indicated high levels of female presence/oviposition activity. Egg numbers on egg traps are typically high only in spring before new hosts are available and again after harvest when populations are typically higher and fewer new hosts are available. This makes the use of egg traps primarily an adjunct to direct monitoring of hosts. The use of pheromone traps should be of greater predictive value. In the spring, in orchards where high numbers of NOW were present, only 2-3 weeks elapsed as male trap capture increased from zero to >50 males per trap. This was observed consistently during three years of early season trapping with pheromone (unmated females). By contrast, numbers of NOW eggs laid on egg traps increased slowly or were very low all season. As the season progressed there was no apparent concordance between egg counts and numbers of males captured in pheromone traps. We are conducting collaborative projects to identify an active NOW sex pheromone blend and develop better female attractants. Success will allow us to develop improved NOW monitoring programs. Also, easy-to-use attractants may serve as an adjunct or replacement for current control practices.

Last Modified: 4/17/2014
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