Life History And Crop Injury

Colorado potato beetles overwinter as adults in the soil within potato fields or in field margins. There are typically one to three generations per year, depending on latitude and the availability of host plants. Adult Colorado potato beetles are oval and approximately 9.5 mm in length and 6.4 mm in width. They are yellow-orange with 10 narrow, black, longitudinal stripes on their elytra (Fig. 1). Adults typically consume 130 to 1200 mm2 of foliage per day and are highly fecund, depositing up to 3000 yellow eggs in clusters of 10 to 50 eggs on the lower surface of host leaves over a period of several weeks. All larvae within an egg mass hatch simultaneously, typically within 4 to 14 days, depending on temperature. There are four instars, and larvae have a distinctive "hunchbacked" appearance, a black head capsule, and two rows of black spots on each side of the body. Instars 1 and 2 are brick red, whereas instars 3 and 4 are pink to salmon. The larvae are voracious feeders, with fourth instars consuming as much as 500 mm2 of potato foliage per day. Larval development requires as little as 8 days or as long as 28 days at average temperatures of 29 and 14°C, respectively. Mature fourth instars burrow into the soil where they pupate. The pupal stage typically lasts 8 to 18 days, depending on temperature.

The Colorado potato beetle is primarily a pest of potatoes, but in some locations is also a pest of tomato (L. esculentum) and eggplant (Solanum melongena). Damage results from defoliation by adult and larval feeding. In potato, yield reductions are related to both the amount of defoliation and the stage of plant growth during which it occurs. Yield reductions in tomato and eggplant result from feeding injury to the fruits, as well as from defoliation.

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