Sweetpotato is one of the most important food crops in
the world and serves as a rich source of carbohydrates,
betacarotene, vitamins and minerals. Sweetpotato
weevil is one of the harmful pests infesting the crop
and remains a challenge for crop cultivation. From
screening of different Ipomoea spp., wild tuberous Ipomoea mauritiana was identified as resistant to sweetpotato weevil infestation. Hence, several extraction
methods for the isolation of proteins from the leaves of
different wild I. mauritiana, Ipomoea palmata, Ipomoea
triloba and Ipomoea obscura were standardised. Further, the crude protein extract from I. mauritiana was
tested against adult sweetpotato weevils using the leaf
dip method. The mortality of the weevils were observed
for crude extract isolated after 48 h at a concentration
of protein ranges from 4 to 5 mg/ml. Further, to study
the effects of crude protein of I. mauriatiana, the protein content and various enzymes from sweetpotato
weevil were estimated after treatment. A significant
reduction in the amount of protein was observed after
treatment with crude leaf protein, which shows the
presence of protease inhibitor activity. Significant difference was observed in the different enzyme activity,
viz. superoxide dismutase, lipid peroxidase, glutathione
peroxidase, glutathione reductase, glutathione s-transferase of sweetpotato weevil, which also reveals the
insecticidal activity of crude protein extract. In conclusion, this is one of the first studies regarding the evaluation of insecticidal activity of leaf protein extract
from the wild I. mauritiana against sweetpotato weevils, and our studies revealed the presence of insecticidal proteins as well as protease inhibitors from the
leaves of I. mauritiana. Further studies will be done to
identify and purify novel proteins from I. mauritiana
using a proteomics approach to evaluate insecticidal
activity against sweetpotato weevil.