have a shorter duration of parasitism. This sequence of generations let the two
species co-exist.
Co-existence mechanisms need further be studied. Salavatian (1991) believed
that 5–6 generation a year spent by wasps which 2–3 of them spent on other bugs.
Two to three generations in cereal fields accepted by authors (Safavi 1973;
Zatyamina and Kletchkovsky 1974; Radjabi 1994, 2000).
8.3.3 Aestivation
The parasitic wasps leave cereal fields and emigrate toward adjacent habitats at the
end of growing season and even prior to it while cereals are going to ripe and are
often semi-green. Other crops, green weeds around the channels, orchards and shade
trees are the places where parasitoids inhabit (Safavi 1959; Viktorov 1967; Martin
et al. 1969; Zatyamina et al. 1976; Radjabi and Amir-Nazari 1989; Salavatian 1991;
Asgari 1995; Iranipour 1996). More temperate and shaded climate, presence of
nectar, honeydew and water sources as well as alternative hosts such as Apodiphus,
Brachynema, Carpocoris, Chroanta, Dolycoris, Eurydema, Graphosoma,
Holcostethus, Piezodorus, Stollia, . . . are crucial for survival during aestivation.
Alfalfa fields are among the most desirable habitats within which parasitoids spend
considerable time even during spring (Zatyamina and Burakova 1980). Parasitism
rates higher than cereal fields were recorded by egg traps tied to plants (Iranipour
1996). Many species of parasitoids are common among cereal fields and aestivation
sites but they are observed in fewer number and discontinueously in resting sites. In
addition, some species only inhabit trees and often emerge late-spring or early
summer coincides to the arrival of sunn pest parasitoids. Alternative hosts have an
important role in the enrichment of overwintering populations. No reproductive
diapause was recorded in these wasps. However, in some regions such as Isfahan,
parasitism was not observed in aestivation sites at all (Safavi 1973).
8.3.4 Hibernation
The parasitoids hibernate inside bark clefts of different trees close to ground level
situated in vicinity of cereal fields. What kind of tree is not important, the only
physical trait of bark is crucial. Elder trees with thicker barks are preferable. In such
places, parasitoids hibernate alone or in small groups including 10–30 virgin or
inseminated females of different species (Safavi 1973). Romanova (1953) and
Radjabi and Amir-Nazari (1989) showed that the presence of trees is not a necessity
in overwintering and parasitoids can survive in perennial weeds, soil crevices etc. A
small reservoir of parasitoid passes into the next year and often emerges prior to host
(Martin et al. 1969; Popov and Paulian 1971; Safavi 1973; Iranipour 1996).
310
S. Iranipour
species co-exist.
Co-existence mechanisms need further be studied. Salavatian (1991) believed
that 5–6 generation a year spent by wasps which 2–3 of them spent on other bugs.
Two to three generations in cereal fields accepted by authors (Safavi 1973;
Zatyamina and Kletchkovsky 1974; Radjabi 1994, 2000).
8.3.3 Aestivation
The parasitic wasps leave cereal fields and emigrate toward adjacent habitats at the
end of growing season and even prior to it while cereals are going to ripe and are
often semi-green. Other crops, green weeds around the channels, orchards and shade
trees are the places where parasitoids inhabit (Safavi 1959; Viktorov 1967; Martin
et al. 1969; Zatyamina et al. 1976; Radjabi and Amir-Nazari 1989; Salavatian 1991;
Asgari 1995; Iranipour 1996). More temperate and shaded climate, presence of
nectar, honeydew and water sources as well as alternative hosts such as Apodiphus,
Brachynema, Carpocoris, Chroanta, Dolycoris, Eurydema, Graphosoma,
Holcostethus, Piezodorus, Stollia, . . . are crucial for survival during aestivation.
Alfalfa fields are among the most desirable habitats within which parasitoids spend
considerable time even during spring (Zatyamina and Burakova 1980). Parasitism
rates higher than cereal fields were recorded by egg traps tied to plants (Iranipour
1996). Many species of parasitoids are common among cereal fields and aestivation
sites but they are observed in fewer number and discontinueously in resting sites. In
addition, some species only inhabit trees and often emerge late-spring or early
summer coincides to the arrival of sunn pest parasitoids. Alternative hosts have an
important role in the enrichment of overwintering populations. No reproductive
diapause was recorded in these wasps. However, in some regions such as Isfahan,
parasitism was not observed in aestivation sites at all (Safavi 1973).
8.3.4 Hibernation
The parasitoids hibernate inside bark clefts of different trees close to ground level
situated in vicinity of cereal fields. What kind of tree is not important, the only
physical trait of bark is crucial. Elder trees with thicker barks are preferable. In such
places, parasitoids hibernate alone or in small groups including 10–30 virgin or
inseminated females of different species (Safavi 1973). Romanova (1953) and
Radjabi and Amir-Nazari (1989) showed that the presence of trees is not a necessity
in overwintering and parasitoids can survive in perennial weeds, soil crevices etc. A
small reservoir of parasitoid passes into the next year and often emerges prior to host
(Martin et al. 1969; Popov and Paulian 1971; Safavi 1973; Iranipour 1996).
310
S. Iranipour