Abstract:
Potato tuberworm,
Phthorimaea operculella
Zeller (Lepidoptera; Gelechiidae) is a
worldwide pest of solanaceous crops. Larvae feed in
side galleries in foliage, stems and
tubers making chemical control unsuccessful, so oth
er control methods should be applied.
In recent years many plants have received genes tha
t encode toxic proteins as a strategy to
resist insect pests. In this study, optimal pH and
temperature of digestive
α
-amylase and
protease activities of potato tuberworm and the eff
ect of triticale (X
Triticosecale wittmack
cv. Sanabad), rye (
Secale cereale
L. cv. Danko) and black nightshade (
Solanum nigrum
L.)
seed proteinaceous extracts against enzymes activit
ies were evaluated using starch 1%
and azocasein 2% as a substrate, respectively. The
optimum pH of
α
-amylase and
protease activities was found to be highly alkaline
. Enzymes inhibition assays showed that
amylase activity was significantly affected by extr
acts from triticale and rye by pH (P=
0.05; maximum effect at pH 9) and influencing of pr
otease activity by extracts mentioned
above did not vary by pHs 8-11 and 9-11, respective
ly. Extracts from black nightshade
seed had no effect on enzymes activity. Inhibition
manner of various concentrations; 1.5,
0.75, 0.375, 0.187 and 0.093 (mg protein ml
-1
) of extracts were dose-dependent. Maximum
inhibitory effect occurred at the highest concentra
tion and the minimum was at the lowest
concentration. In polyacrylamide gel assay, both en
zymes, without inhibitors showed two
isozymes, which at highest concentration of extract
s, both bands disappeared or their
intensity decreased. So, these proteins can be intr
oduced to be encoded in producing
resistant potato crops against potato tuberworm.
Keywords:
Cereals, Digestive enzymes, Potato tuberworm.
