Western flower thrips (WFT) is one of the most damaging pests, world-wide, to ornamental crops. Plant nutrition can play a role in host plant resistance to WFT and in the possible reduction of pesticide usage.This study determined how ger-bera host plant resistance is enhanced when nutrient availability is reduced, as determined by an increase in chemical defenses and a reduction in WFT feeding and abundance. We tested three fertility levels that consisted of OX, 0.3X, or 1X (200 ppm N) the recommended fertilization rate for gerbera. Reducing fertilization increased the total phenolics, which are constitutive secondary metabolites that negatively affect insect feeding. In addition, the accumulation of jasmonic acid (JA), which is a plant hormone that regulates the induced defense response to insect feeding, was greater when fertilization was reduced. The enhanced chemical defenses in lower fertility plants resulted in reduced WFT abundance and feeding damage. Vegetative biomass was reduced in lowerfertility plants, but flower production and the number of days to pollen shed were similar for ger-beras receiving 1X and 0.3X fertilization.Thus, WFT-free plants that received 1X or 0.3X fertility were rated as marketable. Hence, reducing fertilization to a moderate level in gerbera production, which also increased flower peduncle length, can enhance resistance to WFT, while maintaining adequate plant quality.
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