Developing best practices for releasing lacewings in apples

Commodities

• Fruits: apples

Practices

• Pest Management: biological control

Washington apple growers are experimenting with releasing natural
enemies purchased from commercial insectaries. Lacewings
releases, targeting aphids and mealybugs, are the most common.
Aphid and mealybug organic control options are limited and damage
from honeydew production alone can cause $400-$4,000/acre of
yield loss. ≥25% of growers are conducting releases, spending
$153/acre/year. The industry purchases $1M of natural enemies per
year, with demand increasing annually, especially for releases by
drone. Growers’ indicate that their biggest barrier to successful
adoption is lack of best practice recommendations, not cost or
perceived lack of efficacy. However, current recommendations are
based on greenhouse use and are not well-matched to orchards,
which greatly differ in climate, acreage, crop, and target pests.
Therefore, this project addresses a need for scientifically-based
recommendations on how to release lacewings in apple orchards. We
will determine (1a) which release methods provide the most
effective aphid and mealybug control by comparing life stages
(releasing eggs or larvae), available species, and methods
(sprinkled or hanging egg cards). We will compare the efficacy of
the two commercially available species of lacewing,
Chrysoperla rufilabris and Chrysoperla
plorabunda (sold as “C. carnea”). We will conduct
large plot tests of drone-released lacewings to determine (1b) if
they are effective and to what extent release rates need to be
increased for success compared to a ground release. For the most
effective release method, we will (2) identify the release rate
that best balances cost and pest control. Finally, we will (3)
determine if and for how long residues of organic pesticides are
harmful to lacewings, allowing for better integration of chemical
and biocontrol tactics. To increase grower knowledge and adoption
of release best practices, we will develop a “tailgate training
kit” and a natural enemy releases webpage. The bilingual
“Tailgate training kit” will be designed for managers to train
crews, with a large flipchart and a plain language handout
summary for in-field trainings on how to perform releases, and a
pocket flipbook on identification and other key information for
later reference. The natural enemy releases “how-to” webpage will
host summaries of research findings, best practice
recommendations, and four video tutorials on how to conduct
releases (ground and drone), do quality control checks of
lacewings received, and scout after release. A participatory
research framework will be used to increase grower-to-grower
information spread and adoption. Each grower-collaborator will
host a field day, where they will discuss their experiences with
releasing predators and where we will demonstrate release methods
and scouting, in collaboration with insectary representatives.
The grant team will conduct a half-day Natural Enemy Releases
session, with a grower-collaborator panel discussion. At the end
of the project, we will conduct a follow-up evaluation to capture
producer adoption of new practices and the impacts on their
farms. Increased adoption of and success with biocontrol releases
will reduce grower expense on unsuccessful releases and decrease
pesticide use. This will decrease harm to non-target organisms,
pesticide environmental contamination, and farmer and community
exposure to residues.

Research Objectives

1. Determine which method of releasing lacewings results
in the greatest establishment and pest control

a. Compare species, life stages, and cards versus loose eggs

b. Compare drone to ground releases at orchard-scale

2. Determine which lacewing release rate is most
effective for aphid control

3. Determine the effects of organic pesticides on
insectary-reared lacewings

a. Determine acute toxicity of organic pesticides to lacewings

b. Determine the duration that field-aged residues remain
harmful

Education Objectives

1. Increase grower knowledge and adoption of natural
enemy release best management practices:

80% of participants in trainings will gain new knowledge and 50%
will plan to try natural enemy releases on their farms or alter
how they are currently doing releases.

Activity A. Create a toolkit for growers to train their workforce
on lacewing releases

Output: Toolkit

Activity B. Create a web-based resource that acts as a “one-stop
shop” for information on release best practices

Output: Website

Activity C. Increase grower adoption of successful lacewing
releases using a participatory research framework

Outputs: Advisory meetings, Field days, Intensive
Session

2. Disseminate research results to other agricultural
professionals and the general scientific community

Activity A. Scholarly outputs

Outputs: journal articles, conference presentations

Activity B. Additional grower and other agricultural professional
outreach

Outputs: Fruit Matters articles, grower meeting
presentations