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Plants Can Protect Themselves From Aphids And Locusts

December 15, 2003

Moscow biologists have proved that people can use the capability of some plants to protect themselves from vermin insects with the help of biologically active substances.

It has been found that plants can protect themselves from vermin insects. One way is to use substances which the plants synthesise to suppress insects' hormones activity and to disrupt their development cycle. Having studied the way these substances act, people can try to use these substances for their own purposes.

This rseearch became the objective of work by biologists from the Severtsov Institute for Ecology and Evolution Problems, Russian Academy of Sciences. They have investigated substances called precocenes that disrupt activity of the so-called juvenile hormone, which ensures normal larva development and insect propagation. The plants that synthesise precocenes intensely are as follows: Ageratum mexicanum, Phacelia, and possibly chrysanthemum.

The researchers have selected the insect species that are particularly sensitive to precocenes' action: Asiatic locust (Locusta migratoria), green peach aphid (Myzus persicae), greenhouse whitefly (Trialeurodes vaporariorum), and insensitive insects including the honeybee (Apis mellifera) have been selected for the background group.

The researchers fed the insect larvae with the leaves of ageratum, and the result surpassed all expectations. The larvae either died or started to pupate rapidly, but the hatched out adult insects were incapable of reproduction. The larvae's digestive system was disrupted: the intestines reduced in size, and intestinal epithelium cells altered.

This plant precocenes action is similar to that of some well-known insecticides. The alterations affect even the insect's brain, for instance, neurosecretory cells, which send nerve impulses and along with that excrete special substances within the secretion. On top of that, the larvae's wax glands activity was disrupted, these glands secreting wax to protect larvae from drying up. And finally, antennas - insects' organs of sense - underwent alterations, which impeded finding fodder plants and sexual partners. So, the locust, aphid and whitefly have failed to withstand precocenes.

The case is different with the honey bee. This useful and rather domestic insect suffers from parasitical mites, which provoke the disease varroathosis. The mites can be fought with the help of precocenes as they make them sterile. Precocenes do not affect the bees due to some biochemical peculiarities. Therefore, the researchers advise that beekeepers should apply these substances.

Informnauka (Informscience) Agency