Researchers find that water stress changes sugar beet physiology, leaf-miner development and crop damage
Drought affects more than crop growth. New research shows that the severity of water stress can also determine how vulnerable sugar beet is to pest damage.
A team at the University of Göttingen investigated how moderate and severe drought influence sugar beet infested by the beet leaf miner (Pegomya cunicularia), a fly whose larvae feed inside the leaves and create visible tunnels.
The researchers found that moderate drought improved conditions for larval development and increased damage to the crop. Severe drought, by contrast, adversely affected both the sugar beet plants and the pest. The findings were published in the Journal of Experimental Botany.
Sugar Beet Responds Differently as Drought Intensifies
The researchers exposed sugar beet plants to either moderate or severe drought, with some plants also infested by beet leaf miners. They then measured crop growth, leaf area, photosynthesis and other indicators of plant performance, alongside insect development and egg-laying behaviour, according to a press release.
Drought generally reduced sugar beet growth, leaf area and photosynthetic activity. However, the consequences for pest damage depended strongly on the severity of the water stress.
Moderate Drought Makes Leaves More Favourable to Larvae
Under moderate drought, concentrations of certain nutrients increased in the sugar beet leaves. These changes created more favourable conditions for beet leaf miner larvae, which grew particularly well and caused more extensive damage to the plants.
The result suggests that sugar beet experiencing moderate water stress may face a double burden: reduced crop performance combined with increased pest pressure.
Severe Drought Restricts Crop and Pest Development
Under severe drought, the water content and physiological performance of the sugar beet plants declined substantially. Although this placed the crop under greater direct stress, the resulting leaf conditions also considerably restricted larval development.
Female beet leaf miners laid fewer eggs on severely stressed plants, further reducing infestation pressure.
Drought Changes the Signals Emitted by Sugar Beet
Water stress also altered the crop’s chemical communication.
“We observed that drought stress alters both the composition and abundance of plant-emitted volatile compounds, which the beet leaf miner uses to locate suitable host plants for its larvae,” explains Dr Shahinoor Rahman, who carried out the study as part of his PhD research at Göttingen University’s Department for Crop Sciences.
“In addition, females laid fewer eggs on plants experiencing severe stress,” Rahman adds.
The findings demonstrate that drought severity can reshape sugar beet–pest interactions in different ways. Understanding these effects could help breeders, researchers and growers develop more resilient sugar beet varieties and crop-protection strategies as drought becomes a growing challenge for agriculture.
