THE INSECT AND THE PROBLEM

Corn rootworm (Diabrotica spp.), or CRW, is the most damaging insect pest of corn in North America. Larvae feed on roots causing plant lodging and yield loss. Adults feed on silks, leaves, and pollen; silk feeding can interfere with pollination and cause economic damage.

There are four species of corn rootworm present in North America: Western CRW (Diabrotica virgifera virgifera), Northern CRW (D. barberi), Southern CRW (D. undecimpunctata howardi), and Mexican CRW (D. virgifera zeae).

Western and Northern CRW are the most economically important species and found throughout the Midwest Corn Belt. Southern CRW rarely causes economic damage, and Mexican CRW are locally important in Oklahoma and Texas.

Corn rootworm, Diabrotica spp.

PHEROCON^® AM/NB MONITORING TRAP

The PHEROCON^® AM/NB trap is the preferred & highly recommended product for trapping corn rootworm beetles. This sticky trap utilizes yellow as the primary attractant and does not require a lure to capture corn rootworm.

TRAP PLACEMENT TIMING AND PATTERN

Trapping should begin at the blister stage (R2) after silking. For every 10-50 acres, two linear transects of 6 traps each should be arranged down one row and the length of the field on opposite sides of the field. Traps should be at least 165 ft from the edge of the field and spaced at least 165 ft apart. For corn, attach the trap to the stalk directly above the ear by folding the trap with the sticky side out around the stalk, fastening with a twist tie. For soybean, attach the trap to a stake approximately 18” above the canopy. Remove any surrounding leaves that may get stuck on the trap and mark the rows where traps are located.

Schematic drawing of CRW traps in corn or soybean fields (source: Iowa State Extension.

TRAP CAPTURE INTERPRETATION AND ACTION THRESHOLDS

Calculate the average number of beetles captured/trap/week. An average of
<21 beetles/trap/week indicates low populations the following year, 21-50 indicates moderate populations next year, and >50 beetles anticipate a high population the following year. Insecticides and crop rotation and some management tactics that can be considered. Contact location extension authorities and consultants for regional advice.

CIDETRAK^® L

A gustatory stimulant that relies on the compulsive feeding behavior by adult
corn rootworm, and when mixed with stomach poison insecticides, stimulates
beetles to ingest the insecticide, resulting in greater efficacy of insecticides.

More information regarding PHEROCON^® and CIDETRAK^® products may be seen on Trécé’s website or under IPM PARTNER^® Guidelines for Use for Corn rootworm.

Danielle Kirkpatrick, Ph.D.
Global Technical Support Coordinator