On how nitrogen fertilization affects the host election and oviposition behavior of the corn stunt spiroplasma vector, Dalbulus maidis (Hemiptera: Cicadellidae)

The corn leafhopper Dalbulus maidis (Hemiptera: Cicadellidae) is a serious maize pest widely distributed on the American continent. This is the most common leafhopper feeding on corn crops in Argentina and Brazil, causing major economic losses due to its capability to transmit important pathogens, such as corn stunt spiroplasma, and considerably decreasing crop yield. One way to increase crop yield is to elevate fertilizing doses of nitrogen and phosphorus, although this could translate into an increase in pest populations, since changes in host plant quality makes them more attractive to herbivorous insects, positively influencing their population dynamics. This study aims to assess the oviposition preference and the olfactory response of D. maidis to corn plants subject to three levels of nitrogen fertilization (100 ppm, 200 ppm and 300 ppm). Olfactory response was evaluated in a static-air four-way olfactometer using maize plants with different nitrogen fertilization levels as odor sources. Additionally, plants with different nitrogen fertilization levels were offered to females in a multiple-choice assay to assess their oviposition preference. The olfactory response of D. maidis was influenced by nitrogen fertilization, as females oriented toward plants treated with high fertilization levels. Similarly, oviposition preference assays showed that D. maidis females preferred to lay its egg in plants with high fertilization levels. The results herein reported could contribute to the design of integrated pest management strategies that promote balance between crop fertilization to improve yield and insect vector management.