Insect damage to crops is a serious problem for farmers, consumers, and the economy at large. Genetic modification to common crops (like corn) has significantly reduced damage caused by insects that feed off plant leaves, but it has its limitations. One of these limitations is sap-sucking insects, which aren’t affected by the plants’ engineered insecticide.

However, a recent paper in Nature Biotechnology describes cotton that has been genetically modified with an insecticidal protein found in ferns, which might be a safe solution to this issue.

Whiteflies are insects that damage plants by sucking out their sap, which can cause wilting, defoliation, and stunted growth. Whiteflies also spread viral and fungal infections, which further harm crop yield. Cotton farmers don't currently have an effective insecticide that targets these problematic whiteflies. A recent reduction in the use of pesticides among cotton farmers has caused an increase in whitefly-related damage, and the authors of this paper aim to alleviate that damage.

The researchers noted that ferns and mosses are rarely infested by sap-sucking insects in the wild. Extracts from these plants have been used as pesticides in the past, but the factors responsible for the insecticidal abilities haven’t been identified.

The authors began their project by screening many species of fern to look for plant proteins that would kill whiteflies. They found a candidate protein, which they gave the catchy name Tma12. Tma12 binds to the chitin polymers that are a major component of insects’ exoskeletons. After isolating the gene that encodes Tma12, the authors created a transgenic cotton plant that expressed it. They inserted the gene in up to 87 different locations, but only 16 of these genetically modified strains reached maturity. Of those 16 strains, DNA analysis showed that nine were producing the Tma12 protein in sufficient quantities to protect the plants.

The whiteflies that fed on Tma12-producing plants developed abnormally. Very few of them grew into adulthood. In studies that examined the effectiveness of Tma12 against insects other than whiteflies, the authors found that other common pests, like aphids and mealy bugs, were unaffected by the presence of Tma12.

To determine if this transgenic cotton plant would be safe to use in commercial products, the researchers gave rats some food with some of the plants in it. The authors found that the Tma12 was undetectable in the rats, even at the highest levels of exposure, which far exceed what a human might be expected to accidentally ingest. While cotton isn’t normally ingested, it might end up being accidentally consumed by a human; an infant might end up sucking on a baby blanket for example.

Based on these experiments, it looks like cotton that has been genetically modified to express Tma12 might be a viable option for farmers who are looking to increase their yields. However, this is the first study that characterized this protein as a potential insecticide, so further study is definitely needed before any Tma12 transgenic cotton will become available on the consumer market.

Nature Biotechnology, 2016. DOI: 10.1038/nbt.3665 (About DOIs).