Diatomaceous earth. Silica gel. Magnesium carbonate. Dill seed
powder. Black pepper seed powder. as well as Agrothrin and Katel-sous were
evaluated against the rice weevil Sitophilus oryzae (L.) under laboratory
conditions as grain protectantS.
The results showed that the efficiency of the tested materials markedly
increased by increasing the exposure time. All tested materials need an exposure
time of at least three days to give a significant percent mortality except for
magnesium carbonate. Magnesium carbonate at 0.8 % (/w) caused 78.0±8 %
mortality after 14 days. while katel-sous at its recomuended rate (1 %) caused
100% mortality after the saine exposure period.
The only fast acting material is Agrothrifl.it gives 65±5, 60±4 and 52±4
mortality after two days exposure at concentrations of 1.6. 0.8 and 0.4 % (W/W).
All tested grain protectants obviously reduced the percent of -progeny after 60
days with an average 63-99.6 % except for magnesium carbonate, percent
reduction in F1 — progeny for magnesium carbonate at 0.8, 0.6. 0.4 and 0.2 0/0
(w/w) were 55, 56, 30 and 23.6 %, respectively. Dill seed and black pepper
powders at 2 and 4 % (wlw) drastically reduced -progenCy.
Meanwhile, The same grain protectantS were tested against or,VZaC
infestation to wheat grains stored in steel bins at 33±2°C and 55±5 % RH.
Mortality data recorded after 2. 3 and 5 days showed that Agrothrin (0.2 %) was
the most effective and fast acting compound.
In general. using the gastight steel bins enhanced the potentialities of
the tested grain protectantS after 3 or 5 days exposure. except for dill seed
powder.
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