Olfactory discrimination byHeteropsylla cubana (Homoptera: Psyllidae) between susceptible and resistant species ofLeucaena (Leguminosae)

In the field, adult psyllids,Heteropsylla cubana Crawford, oriented significantly more towards the caged seedlings of susceptibleLeucaena leucocephala (Lam.) de Wit than to those of the resistant tree species,Leucaena collinsii Britton & Rose, or the nonhostAmaranthus spinosus L. In a dual-choice bioassay using a still-air olfactometer, the females demonstrated a strong positive response to the hexane extract ofL. leucocephala leaves at 1×10^–3 g equivalents (g eq) of leaf material. The females did not orient to leaf extracts ofL. collinsii at high concentrations but responded positively at a lower concentration of 1×10^–4 g eq. Olfactory discrimination byH. cubana between resistant and susceptible host species should be considered in selection and breeding programs.