The efficiency of petroleum ether extract of black pepper seeds (Piper
nigrum (L) alone and under modified atmosphere (MA) treatments of 25%, 50%
CO2 and 99.8% N2 were investigated in the laboratory at 25± 1°C and 60± 5%
RH against some stored product insects namely: the rice weevil—Sitophilus oryzae
(L.), lesser grain borer—Rhizopertha dominica (F.) and red flour beetle —
Tribolium castaneum (Herbst.).
The results showed that the efficiency of black pepper seeds extract was
concentration-and time-dependent and that extract was more toxic to the adults of
S. oryzae and R. dominica than T. castaneum.
Results of the effectiveness of black pepper seeds extract under different
modified atmospheres showed clearly that the various tested insect species were
more sensitive to seeds extract under modified atmosphere than the seeds extract
alone.
Results of the joint toxic actions of black pepper seeds extract at 0.2 5%
and 0.5% w/w concentrations under MA of 25% CO2 produced additive effects at
all exposure periods for R. dominica and T. castaneum, while in case of S. oryzae
the seeds extract at 0.25% exhibited potentiation effects at 2 and 3- day exposure
periods and an additive effect at 5- day exposure. Also, the seeds extract at 0.5%
concentration indicated potentiation effect at 2 days and this effect turned to
additive effects at longer exposures of 3 and 5 days.
The Co- toxicity values resulted from the seeds extract at 0.25% w/w
concentration and 9 9.8% N2 showed additive effects at all exposure periods for R.
dominica, while with S. oryzae and T. castaneum synergistic effects were found at
short exposure periods of 2 and 3 days but at longer exposure of 5 days an
additive effect was shown.
|
