Corn insect pest

In Mexico there exist two major insect pests of corn, an armyworm Laphygma frugiperda (A. S.), which breeds and feeds in the leaf whorls of young corn, and the larvae of certain coleoptera which inhabit the soil and feed upon the roots of the corn plants. Of these two the armyworm is the most important. Its attack is particularly severe on corn grown during the summer but, as it is able to breed continuously, it is a problem in corn grown throughout the year in the tropics. 

It is very fortunate for the rice producers of the United States that rice, as compared to most crops, is relatively free from insect pests. Metcalf and Flint (2b) list 30 species of insects as being injurious to corn, 20 to wheat, rye, and barley, 31 to leguminous crops, and 23 to cotton, as compared to but 4 for rice. The fact that rice fields are flooded a large portion of the growing season results in ecological conditions unfavorable to numerous insects that otherwise would probably attack this crop. 

The development of natural resistance in corn (Zea mays) to the corn earworm (CEW) Helicoverpa zea) received many contributions. The CEW is a major insect pest of maize and other crops (cotton, soybeans, etc.) the eggs are laid on the silks, and the larvae access the ear by feeding through the silk channel. 

Toxicity to house fly is obviously quite good. Moderate efficacy is demonstrated against the corn rootworm beetles and mosquito larvae. For an insecticide of the prolan/DDT class, the potency demonstrated against the wild strain German cockroach is quite remarkable. Preliminary tests on the larval stage corn rootworm revealed soil activity of a monochloro compound, unlike most previously reported chemicals in this class. Overall, the spectrum of activity is quite broad, although other categories of insect pests must still be tested (e.g., lepidopteran larvae). 

U.S., 90% of soybeans are genetically transformed to be herbicide-resistant 80% of cotton is transformed for resistance to herbicides and, through incorporation of Bacillus thuriengensis, to various insect pests and 50% of field corn is similarly modified for both herbicide and insect resistance [4], None of the crops are used directly for human food, although food use is made of corn and cottonseed oil from genetically modified corn and cotton and the bulk of the transformed soybeans and corn, and cottonseed meal, are fed to animals which enter the human food supply. End-user and consumer nonacceptance of genetically modified foods continues in many quarters. 

IPM programs have been most effective for cotton, sorghum, peanuts, and fruit orchards, but less effective for corn and soybeans. Some of the biological controls include release of sterilized insect pests, use of insect pheromones to disrupt mating, release of natural predator pests, and use of natural insecticides. 

Maysin, a flavonoid C-glycoside originally found in the silks of the Mexican corn, Zapalote Chico, is also found in the leaves of com, teosinte and centipedegrass, which are resistant to the com earworm and the fall armyworm, the major insect pests of corn in the southeastern United States. ITie two insect pests feed in the whorl which has a lower maysin content than earlier leaves. The maysin content of corn leaves is highest in the tips of the leaves connected just below the ear-bearing nodes. In some varieties of corn luteolin C-glycosides related to maysin are shown to be present by HPLC-UV analysis in silks and/or leaves. These varieties are potential sources for the variant luteolin C-glycosides that are likely resistant factors for the corn earworm and the fall armyworm. 

Uses Insecticide for control of soil-dwelling insect pests in corn Tebuthiuron CAS 34014-18-1... 

Beans are grown widely throughout Latin America and are one of the staple foods. As they are often interplanted with corn or other crops, disease and insect control with pesticides is seldom practiced. At present levels of production it is doubtful whether such control would pay. Investment in pest control is economically sound only when it is practiced in conjunction with improved cultural methods and higher yielding varieties. 

Cuts from the silica gel column were incorporated into artificial diets optimized for several economically-important agricultural pest insects, the pink bollworm Pectinophora gossypiella> the tobacco budworm Heliothis virescens> the corn earworm H. zea and the fall armyworm Spodoptera frugiperda. > Monitoring with this artificial diet bioassay, further column chromatography and preparative TLC on silica gel in diethylether-petrol yielded five... 

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