Potato XXII – 6

Colorado Potato Beetle

Whitney S. Cranshaw

Colorado Potato Beetle

Identification (and life cycle/seasonal history)

Colorado potato beetle (Leptinotarsa decemlineata) is a moderately large beetle of broadly oval form.  It is primarily very light brown colored with black stripes running the length of the body.  Adults are sometimes mistaken for the sunflower beetle, but Colorado potato beetle is larger, has all lines running the length of the body (not broken) and is restricted to nightshade family plants.

Winter is spent as an adult under plant debris and other sheltering materials in the general vicinity of previously infested fields.  They become active in May and can be present before potatoes emerge.  If nightshade weeds are present they will feed on these and have a great preference for hairy nightshade which they will preferentially feed on over any other plant.

Eggs are laid as masses.  Colorado potato beetle eggs are yellow-orange and are usually in groups of a couple dozen or more.  The larvae that emerge from the eggs are dark red with a black head and feed on the leaves.  Development through all the larval stages takes about 3 to 4 weeks and late stage larvae are lighter red.  When feeding is complete they move to the soil, dig a small chamber and pupate.  Adults emerge a couple weeks later.  There is often a second generation that occurs in midsummer.  However adult beetles may feed for a few weeks then go into a semi-dormant condition and move to overwintering sites.  As a result one or two generations may be produced.

Plant Response to Damage

Colorado potato beetle adults and larvae chew potato foliage.  Although plants can compensate for minor defoliation (at least 10% leaf area loss) extensive defoliation can reduce yields.  Plants are more sensitive to defoliation after flowering when top growth has largely ceased.

Management Approaches

Natural Controls

Colorado potato beetle seems to be under a high level of natural control.  Important natural enemies include the pink spotted lady beetle, which consumes eggs, the twospotted stink bug, a predator of potato beetle larvae, and a tachinid fly parasite of adult potato beetles.  Outbreaks of Colorado potato beetle are uncommon in the region in large part due to these natural enemies.

Cultural Controls

Rotation of fields can assist in control of potato beetles.  Adults winter around field edges of previously infested fields and may fly long distances, but are less likely to infested if distance to previous potato fields increases.

Chemical Control

Serious problems with insecticide resistant strains are present in much of North America.  To date such problems with pesticide resistance in Colorado potato beetle has not been seen in the region and a very wide range of insecticides remain very effective for control.

Product List for Colorado potato beetle:

Insecticide	Product per Acre	Preharvest Interval, Remarks
Foliar Treatments Allowable for Certified Organic Production
Ecozin, Neemix	as labelled	12 hour reentry.  Azadirachtin, an extract of neem seed.  Has repellent, antifeedant activity and kills as an insect growth regulator.
Entrust	1-2 oz/A	7 day PHI, 4 hour reentry.  Formulation of spinosad available for Certified Organic production.
Planting Time/Soil Treatments
Platinum	5.8 fl. oz/A	12 hour reentry.  Neonicotinoid
Platinum Gold	2.2 fl. oz./1000 row-ft	insecticide (thiamethoxam).  Platinum gold includes fungicide metalxyl.  Planting time treatment.
Admire 2F	0.9-1.3 fl.oz./1000 row-ft	12 hour reentry.  Neonicotinoid insecticide (imidacloprid).  Planting time treatment.
phorate (Thimet)	use labelled rates	72 hour reentry.  Planting time band or in-furrow treatment.  Organophosphate insecticide (phorate).
Di-Syston 15G	use labelled rates	72 hour reentry. Planting time band or in-furrow treatment.  Organophosphate insecticide (disulfoton).
Foliar Applications1
Ambush, Pounce	as labelled	14 day PHI, 12 hour reentry. Pounce and Ambush are formulations of the pyrethroid insecticide permethrin
Baythroid 2	1.6-2.8 fl. oz./A	0 day PHI, 12 hour reentry.  Pyrethroid insecticide (cyfluthrin).
Asana XL	5.8-9.6 fl. oz./A	7 day PHI, 12 hour reentry.  Pyrethroid insecticide (esfenvalerate)
SpinTor, Success	3-6 fl. oz./A	7 day PHI, 4 hour reentry.  Naturalyte insecticide (spinosyns)
Sevin, Carbaryl	as labelled	7 day PHI, 12 hour reentry.  Several formulations of carbaryl (carbamate insecticide)
Imidan 70W	1 2/3 lbs/A	7 day PHI, 24 hour reentry.  Organophosphate insecticide (phosmet) but with lower negative impact on insect natural enemies than most broad spectrum insecticides
Agri-Mek 0.14EC	8-16 fl. oz.	14 day PHI, 12 hour reentry.  A microbial derivate (abamectin)
Provado 1.6F	3.75 fl. oz/A	7 day PHI, 12 hour reentry.  Neonicotinoid (imidacloprid) insecticide.  Maximum 15 fl. oz/A per season
Leverage 2.7	3.75 fl. oz/A	7 day PHI, 12 hour reentry.  Combination neonicotinoid (imidacloprid)/pyrethroid (cyfluthrin)
Actara	1.5 oz/A	14 day PHI, 12 hour reentry.  Neonicotinoid insecticide (thiamethoxam).
endosulfan (Phaser, Thiodan, Thionex, etc.)	as labelled	1 day PHI, 24 hour reentry. Chlorinated hydrocarbon insecticide (endosulfan)
Furadan 4F	1-2 pts/A	14 day PHI, 48 hour reentry)  Carbamate insecticide/nematicide.
Monitor	1 1/2-2 pts/A	14 day PHI, 72 hour reentry.  Organophosphate insecticide (methamidophos).  Has been highly effective against green peach aphid.
Di-Syston 8	2-3 pt/A	30 day PHI, 72 hour reentry.  Organophosphate insecticide (disulfoton)
^RRestricted Use Pesticide. ^1Labelled for chemigation.
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.

Categories: Potato, Leptinotarsa decemlineata, Insects, Potato beetle

Date: 02/08/2004