| Abstract: | The beet armyworm (BAW), Spodoptera exigua (Lepidoptera: Noctuidae) is a highly destructive pest of vegetables and
field crops. Management of beet armyworm primarily relies on synthetic pesticides, which is threatening the beneficial
community and environment. Most importantly, the BAW developed resistance to synthetic pesticides with making it
difficult to manage. Therefore, alternative and environment-friendly pest management tactics are urgently required.
The use of pesticidal plant extracts provides an effective way for a sustainable pest management program. To evaluate
the use of pesticidal plant extracts against BAW, we selected six plant species (Lantana camara, Aloe vera, Azadirachta
indica, Cymbopogon citratus, Nicotianatabacum, and Ocimum basilicum) for initial screening experiment. Four out of
six plant species such as A. indica, N. tabacum, C. citratus and O. basilicum showed promising mortality of more than
50%. Therefore, we selected these four plant extracts for the subsequent experiments. Through contact bioassay, A.
indica showed high mortality 66.63%, followed by the N. tabacum 53.33%, at 10% w/v concentration. Similarly, N.
tabacum showed the highest mortality rate, 66% at 10% w/v concentration, followed by the A. indica 46% through
feeding bioassay. Furthermore, the feeding deterrence assay showed that C. citratus had a high antifeedant index
(?50) followed by A. indica (?39), and N. tabacum (?28). In living plant assay, the N. tabacum extract showed a
low mean damage score 3.6 on living cotton plant followed by C. citratus 4.5 and A. indica 5.5. Hence, extracts of
three plant species provided promising results against the BAW, which can minimize the use of synthetic chemicals,
particularly for small landholding farmers. Further studies are also required to evaluate the effects of these plant extract
against BAW on cotton plants under field conditions to optimize the further use. |
