Assessing the impact of crop rotation on the persistence and efficacy of insect-parasitic nematodes as biocontrol agents for soil-insect pests

Commodities

Practices

Assessing the impact of crop rotation on the persistence and
efficacy of insect-parasitic nematodes as biocontrol agents for
soil-insect pests

Field and specialty crop producers in the North Central Region
are under increasing pressure from buyers to manage key pests,
including Asiatic garden beetle and corn rootworm, more
sustainably. We have preliminary field data suggesting that
insect-parasitic nematodes (IPNs) offer promise on this front,
but many of the factors limiting their effectiveness remain
elusive. With a renewed focus on reducing pesticide use in
agriculture, IPNs have been a subject of increasing research in
recent years. However, previous work in this area has largely
been pest or commodity specific, or limited in scope and scale.
The impact of crop rotation and accompanying cultural practices
on the persistence and effectiveness of these biocontrol agents
has rarely been investigated. As such, these factors remain key
unknowns for producers who are interested in adopting sustainable
pest management practices and exploring the potential soil food
web-related effects of diversifying their cropping systems. Our
proposed work in mint-corn-soybean rotations addresses both of
these unknowns and is specifically rooted in questions raised by
producers.

We will evaluate the persistence of both endemic and introduced
“persistent” IPNs and assess their capacity to maintain
soil-insect pest populations below damaging thresholds as mint,
corn, and soybean are rotated during a 3-year period. Using
experimental plots at one of our Purdue managed farms
(PPAC=Pinney Purdue Agricultural Center) and duplicating these
treatments in commercial farmers’ fields, we will quantify IPN
densities in inoculated and naturally colonized (endemic) fields
over the course of the crop rotation cycle, and measure key
environmental factors known to impact  their persistence and
infectivity against focal soil-insect pests. We expect to gain
key insights into the relationship between crop rotation and the
sustainability and effectiveness of this biocontrol strategy when
deployed against soil-dwelling pests of high-acreage, high-value
cropping systems. Through this work, we will provide growers with
field-based data; quantifying the processes, costs, and benefits
of conserving endemic IPNs, and augmenting endemic populations
with commercially available, “persistent” IPN strains.
Information generated through this research will be disseminated
through established and novel Extension networks we have
developed over the last 5 years to provide growers with a
realistic, unbiased picture of 1) the long-term sustainability of
this biological control strategy, and 2) how it might be used in
tandem with current and future cultural practices implemented on
their farms.

We expect to gain critical insights into the effects of crop
rotation on the persistence and efficacy of insect-parasitic
nematodes (IPNs) - an aspect of biological control that has not
previously been explored in the North Central region. As a result
of our integrated Extension programming, specialty crop farmers
will gain increased knowledge of IPN biology and their potential
as biocontrol agents in rotation schemes that are familiar to the
region. We expect this project to serve as an entry point for
farmers that have not previously adopted biocontrol, with a
broader goal of reducing dependence on insecticides.