We’re switching to nutmeal lures for navel orangeworm traps. Here’s why.

It’s not always easy to make informed navel orangeworm (NOW) management decisions for crops under mating disruption due to the lack of useful data coming from pheromone-baited traps. This season, we’re changing that by switching to nutmeal lures in all Semios NOW traps located in almonds and pistachios.

This improvement will bring major benefits to growers and PCAs primarily focused around a more precise interpretation of navel orangeworm phenology at the orchard level. This is in turn expected to help guide more effective and efficient pest management decisions.

Watch our video below for a quick overview of the changes and benefits:

What’s new for navel orangeworm traps?

We’re switching from male-only pheromone lures to nutmeal lures.

Nutmeal lures are used for monitoring NOW females. These lures attract GRAVID females, a term used to describe sexually primed females. This means that females captured with this lure are actively laying eggs. They can be either mated or unmated since unmated females would still lay infertile eggs.

A nutmeal lure inside a red Semios camera trap, and a close-up look at the lure which contains ground pistachio mummies

Why change to a nutmeal lure for navel orangeworm traps?

Traditionally in the case of navel orangeworm, male-only pheromone lures under mating disruption have been used for the purposes of “sentinel trapping”. Sentinel trapping is the concept that if a male can find a trap, it can find a female.

However, this scenario also becomes a pitfall when using male-only pheromone lures under mating disruption. 

Sentinel traps generally capture a number of moths that are too low to make a reliable estimate of the developmental progression of the population. Some people refer to this reduction in trap capture as “trap shutdown”. 

In contrast, the new nutmeal lure will not cause this reduction in trap capture under mating disruption conditions, giving you a more informed view of your orchard’s NOW population.

What to expect with new nutmeal lure navel orangeworm traps:

1. With the new nutmeal lures, you will see more trap captures than you did in previous seasons because they will not be impacted by mating disruption (see image below).
2. You should also expect that most of the catches will be female NOW and you may see eggs on the liners. Since females can lay infertile eggs prior to mating, eggs on the liner haven’t been shown to indicate the overall mating status of the population you’re monitoring.
3. Being able to track NOW flights throughout the season allows PCAs and growers to monitor NOW development more confidently. This is key to timing sprays more accurately, improving efficacy at times when crop protection is most important. 

Trap comparison between male-only pheromone baited traps (male only, in blue) and nutmeal baited traps (female only, in green). All four NOW flights were captured in the nutmeal-baited traps. In contrast, the male-only pheromone baited traps saw a reduction in trap captures under mating disruption, providing little insight into the NOW population.

One more thing…

Semios navel orangeworm traps will still include the same great benefits growers and PCAs have come to rely on such as:

• Lure and liner changes by professional Semios Field Technicians
• Daily images of trap liners
• Daily pest counts and historical data
• Automated trap catch alerts

As always, our in-house entomologists are available to answer any questions you may have about this change. Please feel free to reach out to us in the comments, or contact us directly.