California entomologist Charles Burks with the USDA Agricultural Research Service in Parlier is helping tree nut growers evaluate a new lure to monitor orchards for infestations of the Navel orangeworm, according to an article written by the ARS’ Dennis O’Brien.

As many growers are aware, NOW (Amyelois transitella) is the top pest in almond and pistachio production and a major pest in growing walnuts.

Burks’ work is about improving the integrated management of insect pests of postharvest concern to commodities produced in Central California.

Currently, some growers use egg traps supplied with almond meal to attract the NOW pest. Growers count the eggs left by mated females who visited the traps. Egg counting is labor intensive and can be unreliable.

Instead of almond meal, Burks tested a NOW lure called BioLure (Suterra) which uses a complicated blend of synthesized female pheromones to attract NOW males. BioLure can be used with a variety of traps and is easier to use, says Burks.

He and his colleagues compared NOW numbers captured in commonly-used traps baited with the new lure or unmated females placed in mesh bags. The study was conducted over several months in almond and pistachio orchards.

The bait – unmated females – was replaced every four days to ensure they were still alive.

The study results, published in the journal Insects in July 2014, suggested the female bait captured more insects (353) than BioLure (212) yet the lure attracted insects for a longer period - 40 days.

The researchers also compared capture results using three different types of traps baited with the lure or live females. The traps were placed at different distances. Counts were made after a single night and over a four-month growing season.

The results, published in the Journal of Economic Entomology in February 2015, suggested that trap design and trap density - the spacing between traps - are important factors.

Along with previous studies on egg traps, the work suggests that while the lure does not trap as many NOW as female-baited traps, it is an improvement over egg traps. It also suggests that the right trap and its optimal trap density can vary, depending on a specific grower’s needs.

The ARS article says Burks’ research could help reduce insecticide use on 1.3 million acres where $7 billion worth of almonds, pistachios and walnuts are grown annually.