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Giant African snails, pink mealybugs: No, it’s not New Year hangover…

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Giant African snails, pink mealybugs: Coming to a crop field near you?

 

You think you have a problem with plant bugs in your cotton? What about a snail that “can reach the size of an average size adult fist … have a very large appetite, and have been known to feed on 500 different plants?”

Or how about the Asiatic rice borer, a single larva of which has been documented as destroying up to 10 rice plants?

Or soybean pod borers, one of the most serious soybean pests in Asia, the female moth of which deposits eggs in soybean pods, which the larva then proceed to eat?

These are among numerous exotic — and very invasive — insects and weeds that the Cooperative Agricultural Pest  Survey (CAPS) program will be on the lookout for in 2011.

CAPS is a partnership between federal and state agricultural organizations to conduct surveillance, detection, monitoring, and management of exotic weeds, plant diseases, insects, nematodes and other invertebrate organisms not native to the U.S.

Kenneth Calcote, branch director of the Plant Pest Division of the Mississippi Department of Agriculture and Commerce, says the 2011 survey in his state will be on the lookout for a number of potentially threatening pests of cotton, rice, and soybeans.

With today’s far-reaching international commerce system, the opportunity for the introduction of non-native pests is great, and as has been demonstrated with kudzu, cogongrass, and other foreign invaders, the ability to adapt and spread can be significant.

Among the possible invaders Calcotte says the CAPS initiative will be looking for in Mississippi this year are:

• The giant African snail, Achatina fulica, is a large terrestrial snail that can reach the size of an verage adult fist. They are known to feed on at least 500 different plants, including peanuts, beans, peas, cucumbers, and melons. When fruits and veggies are not available, they will feed on ornamental plants and tree bark. The snail has both male and female reproductive organs, can lay up to 1,200 eggs per year, and is considered one of the 100 worst invasive species in the world. The snails are frequently found in classrooms in the U.S. and are sold as exotic pets. Agriculture officials fear their being turned loose in the environment could lead to their widespread reproduction.

• The cottonseed bug, Oxycarenus hyalinipennis, which feeds on cotton seeds as the bolls open, reducing yield and seed vitality, as well as staining the lint, which greatly reduces lint quality.

• The pink hibiscus mealybug, Maconellicoccus hirsutus, is native to Africa, India, Egypt, Australia, and Asia, and feeds on more than 300 plant species, including cotton, soybeans, and okra, sucking nutrients from plant leaves and injecting a toxin from its saliva that damages leaves and can kill the plant. It reproduces rapidly, forming large colonies of cotton-like masses.

• Egyptian broomrape, Orobanche aegyptiaca, a parasitic federal noxious weeds, which attaches itself to its host’s root system, robbing it of nutrients and resulting in yield loss.

• Benghal dayflower, Commelina benghalensis, a federal noxious weed, also known as tropical spiderwort, produces viable seeds above and below ground. It is becoming increasingly problematic for glyphosate resistant varieties of crops due to its relative tolerance of the herbicide. The weed produces both above-ground and below-ground flowers that result in viable seeds. A single plant can produce up to 1,600 seeds and can also reproduce vegetatively from cut stems from cultivation activity.

Rice survey pests

• The apple snail, Pomacea spp., is an invasive non-native snail that is a serious risk to the ecocystem, agricultural crops, ornamentals, and various types of nursery stock. It is also a carrier of the rat lungworm parasite, which poses a human health risk. Apple snails reproduce vigorously, each producing hundreds of pink eggs that are laid in masses above the water line.

• The Asiatic rice borer, Chilo suppressalis, is Asia’s most serious rice pest; larval infestations have caused extensive damage and yield loss. One larva can destroy up to 10 plants. Stems weaken and are easily broken as the borer feeds inside stems and nodes. When attacked, seedlings suffer from dying central shoots, and rice produces  empty panicles or few filled grains.

• The South African leaf miner, Hydrellia wirthi, lays eggs in the whorls of young rice plants. After eggs hatch, the maggots enters the leaf blade and begin feeding on the whorl tissue and stem of the developing plant. Several maggots can be found in a single stem. Affected leaves will have elongated dry lesions along the leaf edge and will become dry and curl from the beginning of the lesion to the leaf tip. The leaf will usually break off or remain hanging. Heavy infestations will kill young plants and reduce stand density. Surviving plants will be stunted, resulting in reduced tiller production. The stunted plants are susceptible to drowning and are easily overtaken by weeds.

• Bakanae, Gibberella fujikuroi, is a fungal disease that is primarily transmitted by seed. The fungus, which has contributed to a yield loss of approximately 50 percent in Asia, infests flowers and renders seed sterile, or causes partially filled grains. A characteristic is the elongation of infected plants. Bakanae releases gibberellin, a growth hormone that makes rice plants grow several inches taller than non-infected plants.

• Senegal tea plant, Gymnocoronis spilanthoides, is a wetland weed that is a significant threat to wetland ecology. It reproduces rapidly by seeds or vegetatively and can quickly take over wetlands, blocking streams and drainage channels. The plants can float on still or slow-moving water, or grow as a bush on wet, marshy soils.

• Ye gu, Agginetia indica, is a leafless, parasitic weed that attacks monocots by attaching itself to the roots, robbing plants of nutrients and resulting in yield loss. It grows in dense shade on wet, swampy ground.

• Panicle rice mite, Steneotarsonemus spinki, was found on rice in Puerto Rico, Texas, Louisiana, Arkansas, and New York in 2007. Rice and wild red rice are hosts to the mite, which is considered a serious pest that could reduce rice yields by 30 percent to 90 percent.

Soybean survey pests

• Maritime garden snails, Cernuella virgata, cause damage to seedling crops of wheat, barley, peas, oilseeds, and ornamental plants. Livestock will reject pastures and hay heavily contaminated with the snails.

• Yellow witchweed, Alectra voegelii, a parasitic weed that attaches itself to a host’s root system, robbing it of nutrients and resulting in yield loss.

• The soybean pod borer, Leguminivora glycinivorella Matsumura, is considered one of the most serious soybean pests in Asia. The female moth lays 160 to 170 eggs, 80 percent of which are deposited in soybean pods, where the larva feeds on the seeds.

• Chilli thrips, Scirtothrips dorsalis, are significant pests of chili pepper, citrus, cotton, soybeans, and other crops in Asia, Japan, Africa, and Eastern Europe. The feeding thrips cause deformed leaves and flowers, resulting in yield reduction.

CAPS will also survey for the Benghal dayflower and pink hibiscus mealybug in soybeans.

Farmers can only hope none of these pests are found.

(For more information, contact Kenneth Calcote at 662/325-8488 or e-mail Ken

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