Use of artificial infestation for field bioefficacy assessment of Bt eggplant against the eggplant fruit and shoot borer, Leucinodes orbonalis Guenee (Lepidoptera: Crambidae).

Nineteen (19) BC3F1 lines consisting of 10 selections from BC2F1 Mara x event 'EE-1' and 9 selections from BC2F1 DLP x event 'EE-1' were evaluated in a single confined field trial to assess the field resistance of Bt eggplants and non-Bt eggplant comparators against local populations of eggplant fruit and shoot borer (EFSB) under natural and artificial infestations. This study was conducted not as a requirement by the Fertilizer and Pesticide Authority (FPA) but in response to biosafety regulator suggestions to do artificial infestation. Artificial infestation of EFSB neonates was done 3 and 5 wk after transplanting (WAT). Mean damage by EFSB measured in terms of percentage infested shoots, percentage fruits with holes and EFSB larvae, and larval count was significantly higher in Bt negative plants compared with Bt positive plants. However, the damage in both artificially infested and naturally infested rows for the BC3F1 DLP x EE-1 and Mara x EE-1 Bt positive plants as well as in the Bt negative plants were comparable, suggesting that artificial infestation of EFSB was no longer necessary to augment the natural field population of the insect pest already present in high number in the trial site.