Understanding the Full Arsenal of Pest Control Strategies Required to Defeat the Light Brown Apple Moth.

The light brown apple moth (LBAM) or “Epiphyas postvittana,” is a small moth presenting the U.S. with big problems. Native to Australia, it has invaded New Zealand, the UK and Hawaii and now, the U.S. mainland. Nocturnal in nature, it mates, then lays eggs atop leaves. The eggs hatch into green caterpillars that feed on the underside of leaves, using silk to adhere themselves to the plant. The larvae also use their silk to roll leaves into a cylinder, forming a shelter for feeding. This behavior makes them part of a class of pest moths called leaf-rollers. The problem occurs because the LBAM attacks the leaves of valuable plants and may also damage fruit (Varela et al. 2008). This pest feeds on more than 250 different plant species, and is an economic threat to a number of important crops including: apples, pears, oranges, and grapes. Now, the light brown apple moth, having devasted crops in Hawaii for over 80 years, has migrated to the U.S. mainland.

light Brown Apple Moth
The Light Brown Apple Moth

In 2007, a couple of LBAM’s were found in Berkeley, California. The California Department of Food and Agriculture (CDFA) began installation of pheromone monitoring traps in March of 2007, and by December nearly 16,000 moths had been found in 14 counties in California (Varela et al. 2008; Johnson et al. 2007). Clearly, the pests’ potential threat to U.S. crops was a serious concern to farmers and government entity’s alike.

 

Potential Annual Crop Damage Running into the 10’s, Potentially 100’s of Millions.

 

In an attempt to minimize the creatures spread throughout the U.S., certain counties within California were placed on quarantine and prohibited from either shipping or receiving plants. The highest risk areas are the West Coast, Southwest and Southeast, which are home to significant apple, pear, grape, and orange croplands. USDA entomologists have estimated potential yearly damage in the $77 and $134 million range, should the pest become established (Fowler et al. 2007).

 

Currently, the main focus is on nurseries in nine quarantined California counties. Shipments can leave but each one must be fully inspected and certified free of the pest. This is not an easy job, or cheap: special monitoring techniques must be used, including a pheromone trap at each nursery. Of major concern is the fact that, if plants are found to be infested, they must be treated with the organophosphate: “chlorpyrifos,” a known neurotoxin.

 

How to Manage the LBAM

 

Biological control or “beneficial insects” are considered a reasonable and effective method for controlling the LBAM population. Along with reduced-risk pesticides, a campaign utilizing species such as Trichogramma egg parasitoids, Bacillus thuringiensis (BT) and spinosad should be effective for attacking LBAM during the early developmental stages (Olkowski et al. 1991; Quarles 2005). Another widely used technique involves aerial pheromone applications to disrupt mating. Pheromones are generally a benign and effective way to control pests, however, their application is usually limited to crop production areas. Pheromones alone will probably not eradicate the pest, but tend to be effective in reducing population levels. The process usually involves repeated applications.

 

Mating disruption is another method used in fighting the Light Brown Apple Moth. One California pear farm used annual organophosphate spraying campaigns as a form of mating disruption to reduce LBAM populations. Although effective, it did not result in complete eradication of the pest. (Alway 1998; Quarles 2000). In an Australian citrus crop, Mating Disruption dispensers were able to reduce light brown apple moth infestations by more than 50% over the course of one year, demonstrating that the technique must be used as part of a bigger, overall pest control strategy. LBAMs are also known to respond well to management strategies used with other native leaf rollers.

 

With ever expanding worldwide trade, travel and global warming, it is likely we will see a continued rise in the non-native pests invading new territories. While complete eradication is usually impossible, rigorous management practices can help reduce populations and inhibit their migration. Rigorous import/export protocols combined with the close monitoring of crops and reduced use of chemicals can help protect the future of our crops and economy.