الفهرس 
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Abstract
Laboratory studies were conducted at the Bollwonn Laboratory, Plant
Protection Research Institute to detennine the effect of host species and
different kinds of food on two Trichogramma species, i.e.; Trichogramma
evanescens (native strain) and Trichogrammatoidea bactrae (imported from
USA in 1992). Eggs of six lepidopterous species were used, three of them are
considered as important economical pests for cotton (pink & spiny bollwonns
and black cutwonn), however, the others (rice bran moth, angoumois grain
moth and Mediterranean flour moth) are known as grain pests. The obtained
results can be sunnnarized as follows:
I. Host Inftuenceon Trichogramma spp.:
a. Influence of rearing, hosts:
1. Occurrence of superparasitism:
In the present results, the average number of the two parasitoids’ pupae/
egg and subsequently the percentages of. superparasitism were significantly
correlated with the size of the host eggs. Regarding the present results of the
two Trichogramma species, larger host eggs such as E. insulana and A. ipsilon
have been shown to be able to support the development of more than one
parasitoid larva. 6.36 & 7.2~!cJof eggs parasitized by T. evanescens and 8.73
& 2.810/0 of eggs parasitized by T. bactrae showed superparasitism in E.
insulana and A. ipsilon eggs, respectively. Sometimes up to 3 pupae were
observed! egg although host egg density was not limited (>80 host eggs!
Trichogramma female). However, eggs of the remaining hosts supported
generally the developing of only a single larva and rarely two in each host egg.
2- InDuence on recuD~ityand emerged progeny:
In genera!, fecundity and emerged progeny per T. evanescens female
(37.87 & 36.69/female) were significantly more than tIlose per T. bac”””
female (32.172 & 31.12lfemale). while tile results varied significantly between
tile six host species. T. evanescens and T. bactrae females produced
significantly tile bighest nnmbers of adults (42.65 and 36.031 female) when
reared on P. gossypiella and C. cephD/ollica eggs, respectively. However. the
lowest nnmbers of progeny were produced when these two parasi
toids
were
reared on S. cerea/ella eggs (23.67 and 23.621female,respectively).
3~InBuence on progeny survival:
The percentage of survival (percentage of progeny emerging as living
active adults) didn’t vary significantly between tile two parasitoids however it
varied between tile six hosts. A1t1lough tile highest percentages of T.
evanescens (99.89 & 98.10 %) and T. bac/rae (99.16 & 98.62~.) adults
emergence occurred from tile larger hosts E. inslI/ana and A. ipsilon, no
significant correlation was statistically obtained between the percentage of
survival and the index egg size. r = 0.7910 and 0.79953, for the two
parasitoi~ respectively.
4- laB.nce OB the Sex-ratio and Geaenl Productivity:
Female progeny dominafed those of males, regardless of parasitoid
species or hosts. The ovenill mean percentage of resulted females (68.1\ ±
0.42 and 68.56 ± 0.5 %- for T. evanescens and T. hac/rae females,
respectively) didn’t differ, significant\y between the two parasitoid species.
But rearing on differeIllhosts affiodedsigniticantly the pen:entage of produced
females. Tric/togramma reared on E. imll/ana eggs (the largeSt host size)
produced siglJilicant!Y _ feIna1es (74.54 ± 0.5 & 77.79 ± 0.60 %,
respectively), while those reared on S. cereg/ella eggs (the smallest size)
produced the lowest pereeniage offemales (61.82 ± 0.70& 62.67 ± 0.6%),
General productivity of T. evanescens females (25.14femaleslfemale)
was significantly higher than ilia! of T hac/rae females (21.20 female).
Significantly the highest productivity values for T evanescens were produced
under rearing on C. cephalonica. P. gossypiella and E. insulana (28.72~ 28.27
and 28.11 females/female~ respectively)~ while those per T. bactrae female
were obtained under rearing on C. cephalonica (24.08), E. kuehniella (23.49)
and E. insulana (23.17 females/female.
5. InftueDce ODsize of the parasite females:
T. evanescens females were larger than those of T. bactrae, which reared
from the same host, however, females reared on the larger hosts (E. insulana
eggs) were larger than those reared on the other hosts; the abdominal width
averaged 0.203 & 0.173 nun, while the head width averaged 0.228 & 0.218
mID, respectively. While~ females emerged from S. cerealella eggs (the
smallest host) had the smallest abdominal and head width (0.131 & 0.124 and
0.148 & 0.149 mm, respectively). Statistically there was a close correlation
between the e~’i’index size of the different rearing hosts and that of the
parasites~ abdominal and or bead width sizes.
6. Fec.dity and longevity associated with the size of female
parasitoid:
For all females, which emerged from the same host, abdominal and head
widths were found strongly correlated with both number of progenyl female
and females’ longevity. Moreover. the abdominal width was more closely
correlated with fecunditY and longevity than with head wid1h. thus. abdomen
width appears to be a useful index of Trichogramma quality. In contrarY, the
whole averages of female sizes (which emerged from each of the six
mentioned hosts) correlated insignificantly with the averages of tbeir
fecundity. However, females that had a medium size and reared from P.
gossypiella and C. cepholonica eggs were more fecund than those had larger
sizes and reared from E. insulana eggs.
The longevities of T. evQll<scensfemales, of different sizes, reared from
each of aforementioned hosts varied insignificantly (2.96 - 3.6 days).
However, larger T. bactrae females lived significantly longer than the smaller
ones (2.58 _ 3.84 days). Le.; T. /ractMe females from E. insulana eggs bad the
longest life-span (3.84 daYs), wbile those emerged from S. cerealella eggs
were smaller in size, less fecund and lived the shortest period (2.58 days).
b. IFnrfolumencreesuoltfsthoef alttbeirsnstautdivye hiot sctouspldecbiees:conclnded that potentiality of the
two parasi
toids
on each of the six alternative bosts varied according to the
rearing host. For example, the potentiality of the two parasitoi
ds
when reared
on the six aforementioned bosts and switched to parasitize P. gossypiella or E.
insulana eggs, can be SlJ1llI1UI1’ize as the following:
1. T. evane
scens
; the native parasitoid is generallY. more capable to parasitize
more P. gossypiella OW than T. hac/Me; the introduced parasitoid
(overall avernge of 49.19; 21-70 eggs! female in the former case opposed
to 34.29; 2O-53eggs! female in the latter case).
2. E. _lana, E. /aJehniella and A. ip.<ilonmay be, fairly, considered the best
for rearing T. evanesce’” (64.6,53.96 and 53.7 parasitized P. gossypiella
eggs! female). While E. 1aJehniellaand C. cephalonico are considered lbe
best for rearing T. /rae,””, (46.14 and 45.3 eggs! female) when the target
pest (al\erDIIIiVChoot) is P. gossypiella. On contI8IY, S. cerealella gave
poor capability ofparasitizingP. gossypiel/a eggs (36.3 and 26.5 e~ T.
evanescens and T. bactrae female, respectively, compared to the fonner
hosts.
3. It could be indicated that E. msulana is the best host for rearing T.
evanescens to be used as a hiocontrol agent against P. gossypiel/a, while,
E. kuehniella is the best for rearing T. bact rae for the same propose.
4. A. ipsilon eggs are the most suitable for rearing the two species of
Trichogramma to be used as a control agent against E. insulana eggs.
II. Host Preference:
Two sets were designed to detennine the acceptance and preference of
some lepidopterous hosts to be parasitized by T. evanescens and T. bactrae
females which had been maintained on S. cerea/ella eggs (original culture) for
more than 10 generations. In the first set, Trtchogramma female was offered
the choice between S. cerealel/a eggs (the original host) and those of each of
the other five hosts. Data revealed that the two parasite species accepted to
parasitize eggs of the six lepidopterous species with different levels of
preference (2.0 _ 2.9 contacts & 10.75 - 21.79 parasitized eggs by T.
evanescens and 1.2 _ 3.0 contacls & 6.04 - 32.46 parasitized eggs by T.
bactrae). The two parasitoid spefemales didn’t prefer S. cerealel/a over than
each of the other five hosts.
In the second set, in which the eggs of the six host species were exposed
to Trichogramma females. Eggs of the six lepidopterous host species were
accepted for parasitism, but with different levels of preference. The acceptance
and preference behavior between the two parasitoid species took the same
trend where the statistical analysis of data was not significant While, P.
gossypiel/a eggs were the most preferred by females of the two species over
those of the remaining five hosts.
III. Effect of food kind and concentration on Trichogramma
spp.:
a. Fecundity:
The lowest average of total progeny/ female of T. evanescens and T.
bactrae (30.6 and 14.1 individual) were produced by the starved females. On
the other hand. adding yeast to the 10% sucrose solution or to 100/0 bee honey
enhanced T. evanescens female’s fecundity as they produced the highest total
nwnber of progeny (56.4 /female). In case of T. bactrae, the highest fecundity
of females (37.6 progeny/. female) was reported by offering 20% bee honey
solution to the freshly emerged females with insignificant difference than . those reported from females fed on 100/0 bee honey with yeast added (33.9),
10% sucrose solution (32.9) and pure ~ee honey droplets (32.9 progeny/
female). Data revealed that T. evanescens females (native) has, generally,
higher fecundity (overall mean 45.38 ± 0.82 progeny/ female) than those of T.
bactrae (introduced from USA) which produced an overall mean of 27.68 ±
0.56 progeny! female
b. Female longevity:
By using all the tested foods and concentrations, it could be concluded
that:
1. T. evanescens female’s life-span was always longer than that of T. bactrae
(overall mean 3.25 ± 0.09 in the fonner case opposed to 1.71 ± 0.05 days
in the latter one).
2. Females of the two species lived longer in the presence of nutrition than in
its absence. Starved females of the two species lived for 1.95 and one day,
respectively); however they lived the longest period when T. evanescens
female was fed on pure bee honey followed; insignificantly; by 10%
sucrose + yeast and 10% sucrose solution (4.6, 4.4 and 3.9 days,
respectively), and when T. bactrae was fed on water only (2.7 days),
followed by 10%bee honey + yeast (2.4 days) and pure bee honey (2.3
days ).
3. Adding yeast to water led to shorter life-span than providing the females
water only (from 3.25 to 2.55 days in case ofT. evanescens and from 2.7
to 1.3 days in case of T. bactrae). While, on the contrary adding yeast to
the 10% sucrose solution enhanced female’s longevity (from 3.9 to 4.4
days for T. evanescens and from 1.4 to 1.8 days for T. hactrae).
c. Percentage of emergence:
Insignificant differences were detected in the percentages of emergence
from eggs of T. evanescens which were fed on either of the different nutrition
treatments, while the opposite was true in case of results from T. bactrae
which showed significant differences (86.2% from eggs of starved females -
97.3% when T. bactrae females were fed on pure bee honey).
d. Sex-ratio (percentage of females):
The sex-ratio was always female-biased and T. evanescens had an overall
percentage of females (74.58 %) more than T. bactrae (66.36 %).
Furthermore, the absence of nutrition did’ not influence the percentage of
produced females in progeny.
T. evanescens females fed on sucrose 2001c. + yeast produced the least
percentage of females (64.1 %), however, those fed on 10 % bee honey
solution + yeast produced the highest percentage (85.9 %). On the other hand;
T. bactrae females fed on sucrose 5% + yeast produced the lowest percentage
(59.6 %) and those fed on sucrose 100/0 + yeast produced the highest
percentages (74.2 % females)
e. General productivity:
Productivity may be considered a very important measure of quality.
However, the obtained data revealed the following:
1. The highest productivity by a T. evanescens, female averaged 46.6 females!
an adult female fed on 10% bee honey solution + yeast followed,
insignificantly, by 42.8 by feeding on either pure bee honey or 10 %
,sucrose solution + yeast. The lowest productivity (23 females) was
produced from starved T. evanescens females and those fed on water +
yeast (22.3 females).
2. As for T. bactrae, the overall productivity /female (17.4 females) was lower
than that of T. evanescens (32 females). The highest productivity ofa T.
bactrae female reached 23.4 by feeding the adults on 10% sucrose
solution. Female productivity was drastically reduced to 8.1 females when
T. bactrae females were kept without nutrition
3. Adding yeast to sucrose or bee honey solutions for feeding the parasitoids
increased females productivity of T. evanescens but conversely caused a
reduction on productivity of, T. bactrae females.
4. T. evanescens females appeared better to be fed on either of lOOIc. bee honey
+ yeast, pure bee honey or lOOIc. sucrose solution + yeast. While, T.
bactroe females appeared better to be fed on either lOOIc. sucrose solution
or 20 % bee honey solution.
IV. Storage of Trichogramma at low temperature
a. Storage of developmental stages:
1. Emergence of adult parasitoids from stored eggs:
T. evanescens stored at the prepupal stage (3 days after parasitism) was
the most tolerant to the adverse effect of the low temperature (79.5 ± 1.5%
emergence), however, T. bactrae showed most tolerance when stored at the
first larval stage (one day after parasitism) as the percentage of adults’
emergence averaged 74.3 ± 1.9 %. On the contrary, old pupae (7-days after
parasitism) of the two species were the most susceptible stage to the adverse
effect of the low temperature as the overall percentages of emergence
averaged 47.7 ± 2.9 and 47.8 ±2.7, respectively.
2. Potentiality of Trichogramma females resulting from
storage:
It was clear that the higher percentages of females with successful
parasitization and the higher numbers of parasitized eggs! female were
produced in case of storing the prepupal stage. It is also worthmentioning that,
by storage of the parasitized eggs after 7 days of stinging for 30 days, the
resultant females were completely, unable to parasitize any P. gossypiella eggs
Thus, when storage of Trichogramma is needed, the parasitized eggs are
better to be stored when the parasitoid ·isin the prepupal stage (3 days after
parasitism at 2S0C), as in this case, the resultant parasitoid adults are of higher
potentiality than storage in either of the remaining stages. Also, it is, generally,
advised not to expose the parasitoid to low temperatme when it is in the pupal
stage.
3. Percentage of emergence from eggs of treated females:
Results indicated high percentages of emergence from P. gossypiella
eggs parasitized by T. evanesce”. and T. bactrae females 1hat resulted after
storage at low temperature (8°C.) at different developmental immature stages
of the parasitoid and for different periods up to 25 days. The overall
percentages of the two species from stored parasitized eggs averaged 93.5 ±
0.177 and 92.5 ± 0.22?01c», while those from control eggs averaged 94.6 ± 0.32
and 94.5 ± 0.320/0,respectively.
4. Percentage .ffemales in the progeny (sex-ratio):
In the present study, the sex-ratio in progeny was always female biased
whatever the species, the stored age and the storage period. However, lower
percentage of females in progeny of the two species were senera\1y recorded
by increasing the storage period to 25 days. Generally, the overall percentage
of females in T. evanescens and T. bactrae progeny from stored eggs averaged
64.8 ± 0.7 and 62.6 ± 0.75°/0, respectively, while those from control eggs
averaged 65.8 ± 1.5 and 69.8 ± 1.33, respectively.
b. Storage of adult females:
1. Potentiality .f’TrichogrlUfUlllJ females after storage:
The potentiality of stored females for parasitizing P. gossypiella eggs
was lower compared to the control feIDa1es. Females of the two species
showed a degree of tolerant to the adverse effect of low temperature up to 3
days, however all females that stored for 6 days failed to parasitize any egg.
2. PI.Calf eDlltl’leaee:
High percentages of progeny emerged from P. gossypiella eggs
parasitized by T. ewmeseens and T. hac/rae females 1hat were stored at low
temperature (8°C) up to 4 days. Generally, the overall percentages of
emergence averaged 92.65 ± 0.5 and 90.22 ± 0.8 %, while those from control
eggs averaged 94.7 ± 0.7 and 94.8 ± 1.1%, respectively. However, all progeny
failed to develop in P. gossypiella eggs as the storage period was prolonged to
5 days.
3. Percentage of females in the progeny (sex-ratio):
The overall percentage of females in progeny of stored T. evanescent
female adults (67.36 ± 0.86 %) didn’t vary significantly than control (69.35
il.8 %). As for T. bactrae, a conflicted percentages of females in progeny
were recorded after exposing their parental females to low temperature (8°C)
for 2, 3, and 4 days, i.e.; percentages of females averaged 68.1 ± 1.6 and 63.8
± 1.4 and 68.3 ± 1.06 %, respectively. According to the obtained results, it
could be advised not to expose Trichogramma adults to low temperature more
than three days.