Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

4.12 Nezara viridula 229
Gryon sp.
Some aspects of mating and reproduction of Gryon sp. in India have been
investigated by Velayudhan and Senrayan (1989).
Trissolcus mitsukurii
This important egg parasitoid of Nezara in Japan also attacks the eggs of
several other pentatomids (Kishino and Teixeira 1994) , preferring species
that deposit their eggs in small masses. It is bisexual and the first egg
deposited by a mated female always produces a male. Both sexes have
aggressive behaviour and females drive Telenomus chloropus females off a
pentatomid egg mass (Hokyo et al. 1966b). The fecundity and longevity of
T. mitsukurii were found to be less than those of T. basalis in laboratory
trials at 26¡C and 65% RH. T. basalis parasitised 82.2% of eggs on the
second day of adult life, whereas T. mitsukurii parasitised only 51.3%. On
average, the former laid 250 eggs and the latter 80, and the longevity of
T. basalis was 80.1 days and of T. mitsukurii 42.6 days (Ferreira and
Zamataro 1989).
Too little is known about the dozen other Trissolcus species in Table
4.12.1 to form an opinion of their value in biological control.
Telenomus chloropus (= T. nakagawai)
This is one of the most important egg parasitoids of N. viridula in Japan and
also attacks eggs of N. antennata. Females are parthenogenic, lay about 100
eggs and live for 11 days. They have a high searching ability and can
parasitise all egss in a raft (Nakasuji et al. 1966). The species is oligophagous
and prefers large egg rafts of pentatomids, such as those of N. viridula or
N. antennata, to smaller egg masses of many other pentatomids. When
introduced to the laboratory in Louisiana, USA. females lived for 8 days at
24¡C, laid on average 60 eggs and developed from oviposition to emergence
in 18 days. When reared from eggs of N. viridula which had been reared on
resistant soybean its fecundity was half that of parasitoids reared on
susceptible soybean and its mortality within Nezara eggs was higher (Orr et
al. 1985b).
Although morphological differences have not been found, it appears that
T. chloropus exists as a series of biotypes. It is a widespread polyphagous
parasitoid of pentatomid eggs throughout the Palaearctic Region, but it is
recorded from Nezara only in Japan, Korea and Thailand. The Japanese
biotype rarely produces males, although males occur elsewhere (Jones
1988). T. chloropus from Japan has been released in Australia (Callan 1963;
Field 1984), Brazil (Kobayashi and Cosenza 1987) Hawaii (Davis and
Chong 1968) and the USA (Jones 1988), but has not become established,
possibly due to its requirement for high humidity (85% RH or higher) for
successful emergence (Orr et al. 1985a).