Sweet taste inhibitor compromises aphid feeding and reproduction

Sprays and artificial diets containing lactisole, a sweet taste inhibitor widely used in the food industry, significantly reduced the appetite and reproduction of two important agricultural aphids: Myzus persicae e Sitobion avenae. The compound affected feeding by inhibiting the insects' taste receptors, which depend on sucrose to locate phloem vessels in host plants.

Researchers tested lactisole on artificial diets and wheat and Chinese cabbage plants. The results indicate reduced aphid attachment to the treated sources, reduced sap ingestion time and a decrease in insect weight and fecundity.

In the experiment, both aphids avoided artificial diets containing 1.000 ppm lactisole. The number of nymphs produced by females fed this diet dropped significantly within 24 hours.

Researchers also tested the compound diluted in water for foliar application or irrigation. Spraying reduced the preference for treated plants and the production of nymphs.

Application via the root was even more effective: it caused weight loss in the insects and altered their feeding behavior, measured by electropenetrography techniques.

In the experiments, S. avenae probed the phloem of treated plants more often, but for a shorter period of time. According to scientists, the reduction in the duration of ingestion explains the poorer nutritional performance of the insects. Since aphids extract nutrients exclusively from the phloem, any reduction in this process compromises their survival.

Despite the repellent and performance-reducing effect on insects, the use of lactisole had a side effect: it also impaired plant growth. The fresh mass of wheat and Chinese cabbage decreased after irrigation with lactisole, which may limit its direct application in the field.

According to the scientists, this is the first study to evaluate sweet taste inhibitors as agents in the control of phytophagous insects. The approach paves the way for the development of biorational insecticides based on the modulation of aphids' taste. However, the negative impact on plants requires the development of less toxic derivatives or selective application methods.

More information at doi.org/10.1093/jee/toaf027