Acalymma vittatum, the striped cucumber beetle, is a beetle of the family Chrysomelidae and a serious pest of cucurbit crops in both larval and adult stages. Large numbers of adults emerge from diapause in the spring to feed on the foliage, flowers, and pollen of cucurbit species. Between one and two generations of beetles can pass in a season depending on the region, cucumber flower the final generation settling into another period of diapause to wait out the winter. Females will lay eggs on or in the immediate vicinity of the stem of a viable host plant, often a member of the genus Cucurbita.
Eggs are a bright orange color and less than a millimeter in diameter. Eggs hatch after a short period and larvae feed on the roots of the plant. Striped cucumber beetles can cause significant amounts of foliar damage to cucurbit crops, particularly to older plants, and larval root feeding also damages the plant. The most damage is often seen in the early part of the year during the emergence of overwintering beetles, but feeding damage continues throughout the entire growing season. Grower tolerance for this beetle is very low, due in major part to the transmission of bacterial wilt. Unfortunately, effective control techniques beyond pesticides are few and far between. Research into nematode and other biological control agents continues today.
Some research indicates that striped cucumber beetle damage can be reduced by the use of vermicompost fertilizer compared to inorganic fertilizer. Researchers suggest that the mechanism by which vermicompost reduces beetle damage is due to an increase in phenolic compounds in plants grown with vermicompost. The application of Paecilomyces fumosoroseus to a trap crop is an effective means of controlling the beetle. Brave new world: recent evolution of an insect-transmitted pathogen a seminar given by Dr. Acalymma vittatum, along with other cucurbit-feeding beetles in the genus Diabrotica, are induced to feeding behavior by a class of plant secondary compounds called cucurbitacins, widespread in members of the family Cucurbitaceae. Final Results of the Third Biennial National Organic Farmers’ Survey, Santa Cruz, CA: Organic Farming Research Foundation.
This virus has a worldwide distribution and a very wide host range. 1934, hence the name Cucumber mosaic. Since then, it has been found to infect a great variety of other plants. CMV also induces a type of symptom on leaves known as the “shoestring” effect on many host species. This effect causes young leaves to appear narrow and the entire plant to be stunted. Specifically, CMV can cause cucumbers to turn pale and bumpy.
The leaves of these plants turn mosaic and their rugosity is often changed, making leaves wrinkled and misshapen. Growth of these plants is usually also stunted and produces few flowers. Often, cucumber fruits are oddly shaped, appear gray, and tested bitter. These appearances lead to them being referred to as “white pickles”. Tomato plants are usually stunted and have poorly shaped leaves, or “fernleaf”, when infected by CMV.