الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 140 |  |  |
| | | from | 140 | | |
Abstract
The present study aimed to evaluate the biological effect of some
insect growth regulators (Atabron) as a chitin synthesis inhibitor and
(Admiral) as a juvenile hormone analogue, against 4th larval instar and pupal
stage of Tribolium castaneum, to determine their toxicity. The effect of
sublethal doses LC50 were used to investigate some of the factors influencing
sex pheromone production and perception by T. castaneum. The structure of
the male and female antennae and different types of sensillae were examined
by using the scanning electron microscope before and after treatment.
„« Toxicological studies:-
Both tested compounds significantly induced larval, pupal & adult
mortalities, which were concentration dependant.
All the treated larvae as 4th larval instar showed a high sensitivity to
both tested IGRs more than pupal stage, female pupae were more sensitive
than male after treatment by both compounds and also, Atabron was the
more toxic than Admiral except after female pupal stage treatment.
„« Morphological abnormalities:-
„h Larval instars:
Treatment of the 4th larval instar and pupal stage with the tested IGRs
induced some morphological abnormalities in larval stages, larval- pupal
intermediates were also recorded.
SUMMARY
SUMMARY
273
„h Pupal stage:
Pupae with different degrees of morphogenic malformations such as
pupae with C- shape & pupae with shortened body were recorded, as well as
pupal- adult intermediate.
„h Adult stage:
Some emerged adults have various degrees of malformations. Adults
were completely free but possessed crumpled and incomplete formation of
wings and constricted adults were also recorded.
„« Biological studies:-
Fourth larval instar and pupal stage of T. castaneum were treated with
different concentrations of the tested IGR¡¦s, and some biological aspects of
the treated larval and pupal stages as well as their sub-sequent
developmental stages were determined.
Both tested IGR¡¦s significantly increased the larval and pupal
durations. On the other hand decrease the percentages of adult emergence,
fecundity, fertility of the eggs produced by the adult.
„« Pheromone production and perception by treated and untreated
beetles:-
Treated and untreated rust-red flour beetles, T. castaneum secreted
two kinds of pheromones. The first pheromone called an aggregation
pheromone was secreted by males which was stimulated and attracted both
sexes while, second pheromone called sex pheromone was secreted by
females which was excited and attracted males more than females, although
SUMMARY
274
production and perception of pheromone by untreated beetles were
significantly higher than production and perception of pheromone by treated
one.
„« Effect of solvent on pheromone extraction from treated and
untreated beetles:-
According to the potency of solvents tried in the extraction of
pheromone, the tested solvents could be arranged descendingly in the
following manner: Hexane, diethylether, acetone and chloroform.
Consequently, hexane was used throughout the present study.
„« Effect of pheromone concentration on treated and untreated male
response:-
The treated and untreated male response to sex pheromone increased
with the increase of pheromone titers (0.1, 0.2, 0.3, 0.5, 0.8 & 0.9 female
equivalents), although response by untreated males were significantly higher
than response by treated one.
„« Factors influencing sex pheromone production and perception by
treated and untreated beetles:-
I-Day time:-
Through studying the effect of LC50 (1.2ppm of Atabron, 2.4ppm of
Admiral after treatment 4th larval instar, 12.6ppm of Admiral after treatment
male pupae and 7.1ppm of the later compound after treatment female pupae)
on production and perception adult beetles through different periods of
photophase and scotophase, it was found that times of production and
perception of pheromone by untreated beetles were significantly higher than
SUMMARY
275
times of production and perception of pheromone by treated one. Also, the
time of highest production and perception of pheromone by untreated beetles
at three o’ clock, while the time of highest production and perception of
pheromone by treated beetles at one o’ clock. On the other hand, by
treatment of pupal stage by (10.6ppm of Atabron for males and 8.3ppm of
the same compound for females), it was found that the time of highest
production and perception of pheromone by untreated beetles was similar to
the time of highest production and perception of pheromone by treated one
at three o’ clock.
II-Age:-
Through studying the effect of LC50 (1.2ppm of Atabron, 2.4ppm of
Admiral after treatment 4th larval instar, 12.6ppm of Admiral after treatment
male pupae and 7.1ppm of the later compound after treatment female pupae)
on production and perception adult beetles through different ages, it was
found that the production and perception of pheromone by untreated beetles
were significantly higher than production and perception of pheromone by
treated one at the same ages. Also, the age of highest production and
perception of pheromone by untreated beetles was 4- 6 day old, while the
age of highest production and perception of pheromone by treated beetles
was 8-10 day old. On the other hand, by treatment of pupal stage by
(10.6ppm of Atabron for males and 8.3ppm of the same compound for
females), it was found that the age of the highest production and perception
of pheromone by untreated beetles was similar to the age of the highest
production and perception of pheromone by treated one at age from 4-6 days
old.
SUMMARY
276
It was observed that production and perception of pheromone by
treated and untreated beetles decreased with the youngest sexes then start to
increase until reach to peak and then decreased another time with the
increasing of age until beetles reach to fourteen day old.
III-Hunger:-
The pheromone titer produced by treated and untreated females and
the level of treated and untreated male response were at maximum when
both sexes were well fed. The reverse occurred when both sexes were
hungry. Intermediate levels of pheromone production and male response
were obtained when one sex was fed and other was left hungry, although
production and perception of pheromone by untreated fed or unfed beetles
were significantly higher than production and perception of pheromone by
treated fed or unfed one.
IV-Temperature:-
Low temperature (15 ¢XC) adversely influenced sex pheromone
production by treated and untreated beetles. As the rearing temperature
increased, the pheromone production also increased to reach its maximum
titer at (30 ¢XC). At a rearing temperature (40 ¢XC), the pheromone production
started to decrease again, but the difference was not significant from that at
(30 ¢XC). None of the rearing temperatures (15- 40 ¢XC) tested could inhibit
pheromone production, although production and perception of pheromone
by untreated beetles rearing at different temperatures (15- 40 ¢XC) were
significantly higher than production and perception of pheromone by treated
one rearing at different temperatures (15- 40 ¢XC).
SUMMARY
277
V-Mating:-
Mating did not lower or inhibit treated and untreated female
pheromone production, although production and perception of pheromone
by untreated virgin and mated beetles were significantly higher than
production and perception of pheromone by treated virgin and mated one.
„« The external morphology of treated & untreated male and female
antennae:-
Scanning electron microscopy of the antennae of T. castaneum
was used to compare external structure and number of sensillae
present on antennae of treated & untreated male and female for the
assessment of physical apparatus responsible for sex pheromone
detection.
Seven main types of sensillae are located on the antennae of
untreated males of rust-red flour beetles; include sensillae trichodea
Type I (T1), sensillae trichodea Type I (T2), sensillae trichodea
Type I (T3), sensillae chaetica, sensillae bohm, sensillae basiconica
and sensillae campaniform, while there are only three types of
Trichodea (T1, T2 & T3) on the antennae of untreated female.
The study revealed that LC50 of Atabron and Admiral caused
the formation of abnormal antennae and effected the number and
distribution of the sensillae of both male and female.