Effects of PIX, a Plant Growth Regulator, on Allelochemical Content of Cotton and Growth of Tobacco Budworm Larvae (Lepidoptera: Noctuidae)

Abstract

In 1982, second-instar tobacco budworms, Heliothis virescens (F.), were fed leaves, bracts, and squares without bracts (buds) of ‘Stoneville 213’ cotton, Gossypium hirsutum L., treated with PIX (1,1-dimethyl-piperidinium chloride). PIX was applied at rates 0.0, 0.4, 1.3, and 3.9 liters/ha. Two applications of PIX were made 2 weeks apart. Plant tissues were analyzed for allelochemicals. Relative growth rate (RGR), relative consumption rate (RCR), and efficiency of conversion of ingested food to body tissue (ECI) were measured. Gossypol in buds and leaves was increased by the application of PIX; however, anthocyanin in buds and tannin and total flavonoids in leaves were decreased. Treatment with PIX did not decrease the nutritional indices of larvae. Other than an increase in larval RGR on leaves, PIX had no major effects on nutritional indices. The increase in RGR on leaves possibly was due to decreases in tannin and total flavonoids and possible increases in percentage nitrogen. RGR was greatest on buds while ECI was greatest on leaves. In a test of ’Stoneville 213’ bud parts, anthers were more nutritious than petals or calyx.