Plants emit volatile organic compounds that insects use to find them. A study found that tomato plants given excess nitrogen fertilizer attracted more whiteflies in lab tests, even without visual contact, because the high-nitrogen plants released different odors.
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Seventy five years ago Dr. Painter said that plants are releasing odors that are attracting insects to them. He called them odors. But right now we're 75 years later and we're going to call them VOCs or volatile organic compounds. This review article states that insects are either attracted to and navigate towards preferred plant volatiles or are repelled by and move away from deterrent plant volatiles. There is a lot of research showing that higher than necessary nitrogen fertilization can attract more pest to a crop, but I wanted to find research that was specifically looking at VOC's impact all on their own. So I found this study which did isolate the impact of VOCs on the attractiveness of over fertilized tomato plants to whiteflies. The Y2 olfactometer test also provided strong evidence that the whitefly Females chose the VOCs from the highest fertilized plants without visual or physical contact with the plants. The results of our wind tunnel and olfactometer experiments showed that higher amounts of nitrogen receiving plants, for example T3 and T4 were highly preferred by the whitefly females compared to T1 and T2 nitrogen treated plants, indicating that the behavioral response of the whitefly females could be attributed to quantitative differences of nitrogen induced volatile compounds released by the plants. So that study is just one example of how VOCs or odors can attract a pest to a crop just based on a management practice which was over fertilization with nitrogen.
