β-amino-butyric acid systemically induces resistance to Asian citrus psyllid, Diaphorina citri, in citrus

ß-aminobutyric acid (BABA) is known to induce resistance against several microbial pathogens, nematodes and insects in several host plants. We have been investigating whether BABA induces similar resistance against Asian citrus psyllid, Diaphorina citri, in citrus under greenhouse conditions. Varying concentrations of BABA were applied as a root drench to citrus plants and compared with a water control. Treatments were evaluated by counting the number of eggs, nymphs and adults produced per plant. Production of eggs was reduced on plants treated with 25 mM of BABA, while production of nymphs and adults were reduced on plants treated with 200 and 100 mM of BABA, respectively. Leaf-dip bioassays demonstrated no direct toxic effects of BABA on immature or adult D. citri. BABA-treated plants were characterized by lower levels of iron, magnesium, phosphorus, sodium, sulfur and zinc when compared to control plants. Headspace volatile analysis revealed differential induction of volatile production between BABA-treated and control plants.