HPIPM:PC Pea weevil

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Taxonomy

Domain	Eukarya
Kingdom	Animalia
Phylum	Arthropoda
Subphylum	Hexapoda
Class	Insecta
Subclass	Pterygota
Infraclass	Neoptera
Order	Coleoptera
Suborder	Polyphaga
Infraorder	Cucujiformia
Superfamily	Chrysomeloidea
Family	Chrysomelidae
Subfamily	Bruchinae
Tribe	Bruchini
Subtribe	Bruchina
Genus	Bruchus

Scientific Name

Bruchus pisorum

Common Name

pea weevil

Author: Sue Blodgett

Identification (and life cycle/seasonal history)

Adults are small 1/16 inch gray-brown weevil flecked with light and dark irregular patches. Tip of the abdomen protrudes beyond the wing covers. Adult pea weevils overwinter and emerge about the time that peas are blooming. Adults feed on flowers, leaves or pods, congregating on pea flowers at early bloom. They will mate following a pollen meal. Females lay 1 or 2 eggs on the outside of the pea pod. Larvae hatch within 1 – 2 weeks and burrow into the pod. Larvae are C-shaped, legless with a brown head and creamy white colored body. Larvae develop within developing seed with each developing pea seed supporting a single weevil larva. Larvae feed within pods, and emerge from threshed pea seed as much as one month after harvest to pupate. There is one generation

Sweep net is used to sample adults. One weevil in 25 sweeps can result in 10% infestation at harvest. The threshold is considered to be 2 adults per 25 -180 degree sweeps.

Plant Response and Damage

Weevil infested seed can result in decreased seed weight, yield reduction and dockage at point of sale.

Monitoring and Economic Threshold

A sweep net is used to sample adults. One weevil in 25 sweeps can result in 10% infestation at harvest. The threshold is considered to be 2 adults per 25 (180 degree) sweeps.

Management

Although pea weevil resistance is available there are currently no resistant varieties available in the US.

Cultural Control

Field sanitation, by destroying crop residues, preventing shattering at harvest, eliminating volunteer plants and planting uninfested seed can reduce infestation. Early planting and harvest is desirable

Chemical Control

Product List for Pea Weevil:

Insecticide	Lbs Active Ingredient per Acre (Fl oz. or oz. product)	Preharvest Interval, remarks
Carbaryl 4L, 80S, XLR^1,2	1 – 1.5 qt (4L) 1 ¼ - 1 7/8 lbs (80S) 1 – 1.5 qts (XLR)	PHI 14 days grazing or harvest for forage, 21 days harvest dry seed. Do not apply more than 6 qts (4L or XLR) or 7.5 lbs (80S)/A/ season.
Fury 1.5^R	3 – 4.3 oz	PHI 21 days. 12 hr REI. Do not apply more than 24 oz per season.
Imidan 70 WP¹	1 – 1.3 lbs	PHI 7 day. 10 days for hay or 7 days for forage. Pacific Northwest only. Do not apply more than 4 lbs/A/season. Minimum tank mix of 5 gal/A.
Malathion²	1 – 2.5 pts (8EC)	PHI 3 days. 12 REI. Do not graze or feed treated vines.
Mustang Max1.5ECR	2.72 – 4. oz	PHI 21 days. 12 hr REI. Do not apply more than 24 oz per season.
^R Restricted Use Pesticide, ¹ Labeled for chemigation, ²Several formulations

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.