of 16. However, it deeply declined at higher densities. A vast number of parasitoids
were permitted to oviposit on a few host egg clutches (14 eggs per clutch). Then
individual eggs were separated from the clutches and developed singly in glass vials
to emerge. Number of progeny per a single host egg was divided to four groups;
singletons, twins, triplets, and quadruplets. Females of each group were singly
confined in vials containing different number of host eggs for five hours. Parasitized
eggs were maintained in laboratory and number of progeny was recorded after
emergence. As expected, per capita progeny number was decreased by parent size
(singletons to quadruplets) in all host densities. Nevertheless, per capita number of
progeny unexpectedly did not decrease continuously. It means that number of
progeny per a single egg reduced in densities below four for singleton and twin
parents and remained unchanged for triplets and quadruplets. This may occur due to
larval competition, host injury during handling, or interference during oviposition.
Direct observations do not support contention of competing females. Difference
among the parents in terms of total number of progeny was also lower than
expectation. A maximum 1.74 times more progeny (10.6 vs. 6.0) was recorded at
density of four host eggs in singleton mothers compared to quadruplets. This
difference declined to 1.12 times at density 32. It seems that 12% difference in
fertility between singleton and quadruplet wasps is insignificant. In a similar study
on O. telenomicida both host numbers and parasitoid numbers varied (Iranipour et al.
2013b). Maximum daily fecundity was 21. So no resource limitation was expected
until host/parasitoid ratio remains 20:1. It was true with one exception. In all
treatments in which resource limitation was present parasitism rate was 100%.
Superparasitism rate was higher than O. fecundus; it reached 14.7–29.4% at H/P
ratios above 20:1. A sudden increase in per capita number of progeny occurred at
ratios below 10:1. Maximum progeny was 3.06 per host at the lowest H/P ratio,
which exceeded that of the O. fecundus. The results suggested that female parasitoid
responds to host deficiency by reduction in fecundity rather than increasing
superparasitism.
6.9.2 Family Eupelmidae
Anastatus bifasciatus Forcroy was reported on sunn pest eggs (Iranipour et al. 1998).
Just males were reared in host eggs. The females also collected later from larger eggs
of an unknown moth.
6.9.3 Family Eulophidae
Tetrastichus xanthonelanae Rond was collected from eggs of Galerucella luteola
Mull. (Col. Chrysomelidae) (Azmayesh-Fard and Esmaili 1981). This is a serious
pest of elm trees in landscapes of some regions. Larvae defoliate elm trees and
6 Egg Parasitoids: Chalcidoidea with Particular Emphasis on Trichogrammatidae
221
were permitted to oviposit on a few host egg clutches (14 eggs per clutch). Then
individual eggs were separated from the clutches and developed singly in glass vials
to emerge. Number of progeny per a single host egg was divided to four groups;
singletons, twins, triplets, and quadruplets. Females of each group were singly
confined in vials containing different number of host eggs for five hours. Parasitized
eggs were maintained in laboratory and number of progeny was recorded after
emergence. As expected, per capita progeny number was decreased by parent size
(singletons to quadruplets) in all host densities. Nevertheless, per capita number of
progeny unexpectedly did not decrease continuously. It means that number of
progeny per a single egg reduced in densities below four for singleton and twin
parents and remained unchanged for triplets and quadruplets. This may occur due to
larval competition, host injury during handling, or interference during oviposition.
Direct observations do not support contention of competing females. Difference
among the parents in terms of total number of progeny was also lower than
expectation. A maximum 1.74 times more progeny (10.6 vs. 6.0) was recorded at
density of four host eggs in singleton mothers compared to quadruplets. This
difference declined to 1.12 times at density 32. It seems that 12% difference in
fertility between singleton and quadruplet wasps is insignificant. In a similar study
on O. telenomicida both host numbers and parasitoid numbers varied (Iranipour et al.
2013b). Maximum daily fecundity was 21. So no resource limitation was expected
until host/parasitoid ratio remains 20:1. It was true with one exception. In all
treatments in which resource limitation was present parasitism rate was 100%.
Superparasitism rate was higher than O. fecundus; it reached 14.7–29.4% at H/P
ratios above 20:1. A sudden increase in per capita number of progeny occurred at
ratios below 10:1. Maximum progeny was 3.06 per host at the lowest H/P ratio,
which exceeded that of the O. fecundus. The results suggested that female parasitoid
responds to host deficiency by reduction in fecundity rather than increasing
superparasitism.
6.9.2 Family Eupelmidae
Anastatus bifasciatus Forcroy was reported on sunn pest eggs (Iranipour et al. 1998).
Just males were reared in host eggs. The females also collected later from larger eggs
of an unknown moth.
6.9.3 Family Eulophidae
Tetrastichus xanthonelanae Rond was collected from eggs of Galerucella luteola
Mull. (Col. Chrysomelidae) (Azmayesh-Fard and Esmaili 1981). This is a serious
pest of elm trees in landscapes of some regions. Larvae defoliate elm trees and
6 Egg Parasitoids: Chalcidoidea with Particular Emphasis on Trichogrammatidae
221