الفهرس 
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Abstract
Summary
Bacillus rhuringiensis entomopathogens was observeevd-<-s-electively toxic to a 0
wide variety of insect species. The pathogenic properties;S 0 due toa 0 number 0 of
toxins released and activated in the midgut of the target insect. The most
distinctive portion of the toxin produced by these bacilli is the &-endotoxin, a
protein crystals formed during sporulation. These crystalline inclusions was
isob.~d. screened and tested against several pests infesting stored produ~ts.
Beside the total culture preparation, purified crystals was also tested. Moreover,
L these crystals was fractionated, analyzed in 8DS-PAGE . Results :JIC
comparatively evaluated with a previously publishing of toxins against
Lepidopteran and Dipteran insects.
SDS-P AGE analysis of six Bacillus thuringiensis isolates indicated that ’
the crystal composition grouped in three major fractions (13SKDa, 65KDa and
28K.Da). It ’0”;;]8 estimated from the data of 8DS-PAGE and the volumetr.c
analysis of velocity sedimentation pattern that all the tested isolates does not
produce equal amount of crystals or crystal fractions. in Bacillus thuringiensis ,”
tenebrionis, only one fraction of approximately 65MDa was observed, the same
was observed with Bt. san diego however the amount of the toxin extracted
exceeds three times more than the relative tenebrionis spp. Moreover, bioass:r:’
indicated.that both isolated exhibiting a selective toxicity toward Coleopter::.a bu~
not the other orders of insects submitted in the tests ..
plasmid, however ’this possibility does not exclude the c~mosoma1location. The . .. :.
A p{Jtential genetic information is encoded by agenets) located in the
. ~;)
difference ,’n bioassays against insects may reflect the difference in the plasmid
pattern ob: -rved, where the number and size of the plaShud varies considerably
,,
1
among the Bacillus isolates. The sizes of the plasmid was foundincluded in the
range from 1.9 to >150MD~ This does not reflect the number where plasmids are
always exists in several forms (relaxed, circular, coiled, and super coiled forms),
This deviation in the plasmid pattern may also due to different proce.’ures
used for plasmid isolation, storage and nutritional conditions required for
maintaining th~_b~acterial isolates.
The susceptibility tests of both Coleopteran pathogens usmg feeding
technique against Tribolium confusum and Trtbolium castaneum indicated a
significant difference between adult and larval stages of both insects tested. It was
also observed that larvae and adults of T. corfusum arc more susceptible than T
castaneum toward the biocide tested. In addition, Bacillus thuringiensis san dieg a
was more effective than Bt. tenebrionis when applied against T. confusum
however both pathogens almost have approximately the same effect on T.
castaneum. Purified crystals used for testing the insects were relatively higher
than the average required for testing T. castaneum, while spores were not
effective even at high doses applied.
Testing the biological activity of the purified crystals of Baculus
~~- ,,’.v) i”,-,,~
thurtngiensis san diego against Calosobruchus maeuJatJJ5WffS almost 4.99 1’01”:’::’
more toxic than the spore/crystal preparations of the total native isolateFinally, the overall evaluation obtained from the ~sults presented in this
study provides encouragement that the Bt. s~ diego ,~s an indicator of the
comme.rcial importance as safe and effecti.ve biological Jgent for the control of
stored grain insects.