8.5 Biostatistics of the Egg Parasitoids of Sunn Pest
Many criteria are used for preliminary screening of natural enemies. Searching
efficiency, attack rate, reproductive potential, population growth rate, host specificity, and synchrony to host are among the most important of them. Synchronization is
not important in inundation programs (van Driesche and Bellows 1996). Many of
these criteria are examined by functional and numerical response, life table, and host
preference studies in laboratory. These parameters and effect of different environmental factors such as host quality, temperature, host density, and other competitors
as well as the intrinsic difference among geographical populations and species were
evaluated on egg parasitoids in numerous studies.
8.5.1 Effect of Internal Factors
The intrinsic difference among species, populations, individuals, subspecies, biotypes etc. was studied in different works. Comprehensive comparison among species
hardly is feasible. This is because there are few studies in which two species or more
were studied simultaneously. On the other hand, comparison among different studies
is not an intact and flawless work. Different scientists obtained very different results
even for a single species because parasitoids are very sensitive to physical conditions. A small difference in experiment condition or regional populations reflects a
large discrepancy in biological parameters. For example, total fecundity of
T. grandis showed three-fold difference between Amir-Maafi (2000) and Bazavar
et al. (2015) researches. Physical conditions, as well as, the intrinsic difference
between populations may be responsible for these variations. In order to separate
these sources of variation, comparisons should be done only under the same physical
conditions and at the same time. Unfortunately, few studies provide this requirement. Hence, we can do only some comparisons among species by referring to
different works.
8.5.1.1 Effect on Life History
In a moderate temperature of 24–26
C, by providing unlimited resources, least
value for the intrinsic rate of increase (r m ) among egg parasitoids of sunn pest was
recorded as 0.14–0.21 d
À1 for T. djadetshkoe (Abdi 2014), raised to 0.366 d
À1 in
T. grandis (Amir-Maafi 2000). The value of this statistic for the other species is
0.3–0.314 for T. vassilievi (BenaMolaei 2014), 0.266–0.272 for T. semistriatus
(Asgari et al. 2001; Kivan and Kiliç 2006a), 0.205 to 0.252 for Ooencyrtus fecundus
(Ahmadpour et al. 2013), 0.224–0.234 for O. telenomicida (Rafat et al. 2013).
Reproductive parameters such as total fecundity, gross and net reproduction rates
(GRR and R 0 respectively) showed the highest variability among the other life
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S. Iranipour
Many criteria are used for preliminary screening of natural enemies. Searching
efficiency, attack rate, reproductive potential, population growth rate, host specificity, and synchrony to host are among the most important of them. Synchronization is
not important in inundation programs (van Driesche and Bellows 1996). Many of
these criteria are examined by functional and numerical response, life table, and host
preference studies in laboratory. These parameters and effect of different environmental factors such as host quality, temperature, host density, and other competitors
as well as the intrinsic difference among geographical populations and species were
evaluated on egg parasitoids in numerous studies.
8.5.1 Effect of Internal Factors
The intrinsic difference among species, populations, individuals, subspecies, biotypes etc. was studied in different works. Comprehensive comparison among species
hardly is feasible. This is because there are few studies in which two species or more
were studied simultaneously. On the other hand, comparison among different studies
is not an intact and flawless work. Different scientists obtained very different results
even for a single species because parasitoids are very sensitive to physical conditions. A small difference in experiment condition or regional populations reflects a
large discrepancy in biological parameters. For example, total fecundity of
T. grandis showed three-fold difference between Amir-Maafi (2000) and Bazavar
et al. (2015) researches. Physical conditions, as well as, the intrinsic difference
between populations may be responsible for these variations. In order to separate
these sources of variation, comparisons should be done only under the same physical
conditions and at the same time. Unfortunately, few studies provide this requirement. Hence, we can do only some comparisons among species by referring to
different works.
8.5.1.1 Effect on Life History
In a moderate temperature of 24–26
C, by providing unlimited resources, least
value for the intrinsic rate of increase (r m ) among egg parasitoids of sunn pest was
recorded as 0.14–0.21 d
À1 for T. djadetshkoe (Abdi 2014), raised to 0.366 d
À1 in
T. grandis (Amir-Maafi 2000). The value of this statistic for the other species is
0.3–0.314 for T. vassilievi (BenaMolaei 2014), 0.266–0.272 for T. semistriatus
(Asgari et al. 2001; Kivan and Kiliç 2006a), 0.205 to 0.252 for Ooencyrtus fecundus
(Ahmadpour et al. 2013), 0.224–0.234 for O. telenomicida (Rafat et al. 2013).
Reproductive parameters such as total fecundity, gross and net reproduction rates
(GRR and R 0 respectively) showed the highest variability among the other life
314
S. Iranipour