Viruses can help combat cotton caterpillar

Cotton farming in Pakistan is hampered by the cotton leafworm, a kind of caterpillar that is becoming increasingly resistant to insecticides. PhD candidate Ghulam Ali looked for and found baculoviruses that kill the caterpillars, thereby putting a biological pest control method centre stage.
Albert Sikkema


Large-scale cotton farming in Pakistan relies almost entirely on BT cotton, a genetically modified variety with a gene of the Bacillus thuringiensis soil bacterium built into it, which causes the plant to manufacture a poison against caterpillars. The common cotton caterpillar, Heliothis zea, has almost disappeared, but has made way for another caterpillar, Spodoptera litura, which is resistant to BT cotton.

Pakistani entomologist Ghulam Ali set out to look for a biological method of pest control that would work against this new cotton pest. He took samples in several cotton-farming areas of Pakistan and identified a type of virus called SpltNPV. He determined with a test that four members of the SpltNPV family, from different regions, were capable of quickly destroying the cotton caterpillar. Ali also found the virus’s DNA information that could be responsible for the accelerated death of the caterpillars.

These virus types could develop into a biological pest control method for the cotton sector in Pakistan, says Ali’s supervisor Just Vlak. But Ali would have to go through several steps first. He would have to find a breeding company for the pest insect Spodoptera litura, so the virus could propogate in it. And he would need to persuade Pakistani agricultural extension workers and cotton farmers to switch from insecticides to biological pest control.

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