Beetle, cucumber

Protection Offered Shaking will dislodge any pest that crawls freely about on plants without clinging, including Colorado potato beetles, cucumber beetles, earwigs, Japanese beetles, and weevils. 

Spotted cucumber beetles are greenish yellow, iy2-ln (6-mm) beetles with 11 black spots on their wing covers. Overwintering adults emerge from under crop residues In spring and lay eggs In the soil close to plants. Their... 

Symptoms Southern corn rootworms feed on corn roots, often killing young plants and weakening older ones. Striped cucumber beetle larvae feed on the roots of squash-family plants only, killing or stunting the plants. Adults of both species feed on leaves, stems, flowers, and fruit of squashes and other crops. 

For some herbivores, the responses to herbivore-induced plant odors differ under different circumstances. For instance, the spider mite I urticae is more attracted to healthy lima bean leaves than leaves that emit volatiles induced by spider mite infestation (Dicke, 1986 Dicke and Dijkman, 1992). However, Pallini etal. (1997) found that the same mite is attracted to cucumber plants that are already infested by conspecifics. In contrast, T urticae avoids the odor of cucumber plants under attack by the western flower thrips, FranJdiniella occidentalis, which is a herbivore but also feeds on spider mites. Bark beetles can cause strong reactions in their host trees, resulting in the emission of a blend of volatile terpenoids that, in combination with aggregation pheromenes, is used in mass attacks. These same substances may attract predators (Byers, 1989) and parasitoids (Sullivan et al, 2000 Pettersson, 2001 Pettersson et al, 2001) to infested trees. 

The blossoms of Cucurbitaceae are well known to be highly attractive to many species of Diabrotica beetles. However, the volatile compounds that act as attractants differ in different Diabrotica species. Cinnamaldehyde strongly attracts the spotted cucumber beetle, Diabrotica undecimpunctata hoivardi, whereas 4-methoxycinnamaldehyde is a specific attractant for the western corn rootworm, Diabrotica virgifera virgifera.51 The northern corn rootworm, Diabrotica barberi, and Diabrotica cristata are attracted to eugenol, cinnamyl alcohol, and 2-(4-methoxyphenyl)ethanol. Volatiles of maize, one of the host plants, also attract D. v. virgifera... 

Ryania is made from the ground roots of the tropical shrub Ryania speciosa. The active principle of ryania is the alkaloid ryanodine (C25H35NOu). Ryania is used for controlling aphids, cabbage loopers, Colorado potato beetles, diamondback moths, cucumber beetles, leafhoppers, corn earworms, European corn borers, codling moths, citrus thrips, and so on. Its oral LD30 in rats is 1200 mg/kg so it is practically nontoxic to mammals. 

Leaves skeletonized. Cause Leaf-feeding beetles. Japanese beetles are prime suspects here, although other beetles, such as spotted cucumber beetles and rose chafers, may also attack. Handpick or spray with a solution of 1 tablespoon 70 percent isopropyl alcohol to 1 pint prepared pyrethrin mixture. Repeat every 3-5 days until beetles are gone. 

Cucumber beetles also eat asparagus leaves. For description and controls, see Leaves with chewed holes" on page 215. 

Leaves with chewed holes. Cause Cucumber beetles. Adults are / " long, greenish yellow beetles with black stripes or spots. See page 214 for an illustration of the insects and damage. They attack young leaves and should be controlled immediately, as they can spread bacterial wilt or viruses. Treat plants with a commercial pyrethrin spray or dust. Prevent problems by planting cultivars, such as Liberty and Wisconsin SMR58 , that are tolerant of cucumber beetles. 

Leaves with yellow patches older leaves mottled and distorted. Cause Mosaic. For an illustration of this disease, see page 214. Remove and destroy diseased plants. Control aphids and cucumber beetles because they spread the virus. Reduce problems by planting cultivars. such as Comet , Fancipak , Liberty. Monarch, Score , Slicemaster , Striker, and Wisconsin SMR58 , that are... 

Leaves with chewed holes. Cause Cucumber beetles, jse insects spread... 

Vines wilt at midday, starting with younger leaves leaves remain green. Cause Bacterial wilt. As the disease progresses, leaves fail to recover, and die. Cut wilted stem and touch the tip of your knife to the sap. If it is milky, sticky, and astringent, your plant is infected. For an illustration of this disease and technique, see page 148. Destroy infected plants immediately. Prevent problems by controlling cucumber beetles, since they spread the disease. 

Potatoes with large, shallow feeding scars or hollow cavities. Causes White grubs cutworms cucumber beetles. White grubs are fat, whitish larvae that tend to feed over the whole surface of the potato. Adults are Japanese or June beetles. Apply parasitic nematodes to the soil before planting to control. 

Spotted cucumber beetle larvae (also called southern corn rootworms) are white with brown heads and grow up to A" long. Adults are A", greenish yellow beetles with black spots. Treat infested plants with a commercial pyrethrin spray if the damage is severe. P revent problems by covering plants with... 

Beneficial Effect Both larvae and adults prey on cucumber beetles, corn rootworms, aphids, grasshopper eggs, caterpillars, and beetle larvae. 

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