The impact of plant associations onMacrosteles quadrilineatusmanagement in carrots

Abstract

AbstractHabitat diversification can influence the interactions of insects with plants and this can be used in agroecosystems for the management of pest populations. Plant diversification can be achieved through planting crops, such as trap crops, or by adjusting weed management. Aster leafhopper,Macrosteles quadrilineatusForbes (Hemiptera: Cicadellidae), is a polyphagous species that uses cereals, vegetables, and weeds as host plants. The influence of weeds onM. quadrilineatusabundance was investigated experimentally in carrot [Daucus carotaL. cv. Canada (Apiaceae)] field plots by adjusting the level of management of two groups of weeds (broadleaf and grass) and by comparing it to weed‐free plots. The preference ofM. quadrilineatusfor different cereal and weed species relative to carrots was tested in choice test assays. Habitat context influenced the abundance ofM. quadrilineatusin the field experiments. The presence of border crops such as oat, rye, barley, wheat, and triticale did not significantly attract or repel this insect to carrot plots compared to the no‐border treatment. However, spelt‐bordered plots had 42% fewerM. quadrilineatusthan three treatments, triticale, wheat, and barley, that had the highest insect abundance. The type of weed management affectedM. quadrilineatusabundance in carrot plots, but not the frequency of herbicide application. Plots that had carrot growing with broadleaf‐weeds had about 59% fewerM. quadrilineatuscompared with those growing with crabgrass or carrot alone. In the greenhouse choice tests, grasses (e.g., cereals) attracted and broadleaf‐weeds repelledM. quadrilineatusrelative to carrots. In summary, carrot growers may be able to manage this pest by reducing the interaction of cereal cover crops with carrots and eliminating grassy weeds in commercial production fields.