Biotech Updates

Controlling Insect Pests Using Genes from Other Species

February 1, 2023

BTI’s Honglin Feng brushes some green peach aphids off of a tobacco plant. Inset: a closeup of the action. Photo Source: Boyce Thompson Institute

One of the promising approaches to pest control is to target insect genes that are essential to their survival. However, it is a challenge to find targets whose silencing will kill pests but not beneficial insects. A team of researchers at the Boyce Thompson Institute (BTI) led by Georg Jander, has shown that horizontally transferred genes (HTGs), or genes transmitted from one species to another, found in insect genomes are valid targets for selectively killing green peach aphids, whiteflies, and potentially other insects that cause major damage to food crops worldwide.

In a 2016 study, a team led by BTI professor Zhangjun Fei identified 142 genes that were likely HTGs in a subspecies of whitefly. For this study, Jander's team sequenced the genome of a strain of green peach aphid and identified around 30 HTGs, most of which were also present in other species of aphids but not in whiteflies. The research team used RNA interference (RNAi) to silence HTGs in aphids and whiteflies. They used a virus to deliver the RNAi molecule into the plants that the insects fed on, a strain of wild tobacco species Nicotiana benthamiana previously developed by the Jander lab.

In aphids, the team silenced 11 different HTGs of bacterial, fungal, viral, or plant origin; which decreased aphid survival. When larvae of seven-spotted ladybugs and adult mealybug ladybirds fed on the aphids from the treated plants, the RNAi molecules were transmitted to the ladybugs. However, it did not cause adverse effects because their genomes lacked the targeted genes. In whiteflies, silencing five different HTGs had adverse effects on survival, demonstrating the potential for expanding this method of pest control to insects beyond aphids. While silencing the individual HTGs caused measurable reductions in insect survival, the size of those impacts was not large, Feng said. “The reductions were 40% or less in most cases, and often around 20%.” Feng now plans to “stack” targets by silencing multiple HTGs in the insect pest simultaneously, to see if the combination treatment could have a greater killing power than silencing the individual HTGs.

For more details, read the article in BTI News.

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