Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

220 Biological Control of Insect Pests: Southeast Asian Prospects
Clarke and Walter (1992) postulate that, because N. viridula oviposits
only rarely during summer in southeast Queensland, T. basalis is largely
without its preferred host for 60Ð90 days during which daily temperatures
average more than 25¡C. This exceeds the average survival time of adult
females at this temperature. Adult survival of T. basalis in summer is thus
held to be the most likely factor limiting its populations. This postulate
assumes that the egg masses of native pentatomid hosts of T. basalis are also
in short supply over summer. It also appears not to apply to the far hotter but
moister climate of the Ord Irrigation Area in far northern Western Australia,
where N. viridula continues to be under generally excellent control.
AFRICA
N. viridula does not appear to be regarded as an important pest in northern
Africa where its eggs are attacked by a number of Scelionidae, including
Trissolcus aloysiisabaudiae, T. basalis, T. lepelleyi, T. maro, T. sipius and
Telenomus seychellensis. Trissolcus basalis occurs mainly in coastal areas
and the others are reported primarily from the eastern and central half of the
continent. T. basalis was introduced to South Africa from Australia, New
Zealand and USA, although there is some evidence that it may have already
occurred there prior to these introductions (Giliomee 1958; Greathead
1971). In Malawi eggs laid on macadamia were reported to experience an
average of 74% parasitisation by Trissolcus maro and Telenomus
seychellensis (Croix and Thindwa 1986). In Somalia Trissolcus
alloysiisabaudiae is very abundant and may cause 100% parasitisation of
N. viridula eggs on cotton (Paoli 1933). T. lepelleyi and T. sipius attack
N. viridula eggs in East Africa, the latter being known only from Kenya.
Psix striaticeps, which occurs in tropical Africa and India, has been bred
from N. viridula eggs (Jones 1988).
ARGENTINA
N. viridula was first recorded in 1919. Since the native tachinid parasitoid
Trichopoda giacomellii was unable to maintain populations at sufficiently
low levels, three parasitoid wasps were introduced, of which the most
effective is Trissolcus basalis (Crouzel and Saini 1983; Porta and Crouzel
1984).
In Buenos Aires Province, mortality of N. viridula eggs was found to be
due mainly to parasitisation by T. basalis, that of 1st to 3rd instar nymphs to
predation and that of adults (together with reduction in egg production) to
parasitisation by Trichopoda giacomellii. Adult mortality and reduction in
egg production was found to be density dependent. Three egg parasitoids
were present, Trissolcus basalis (95% of total parasitisation), Telenomus
mormideae and Telenomus sp.. Nymphal mortality was principally due to
spiders and predatory bugs (Podisus sp.), although there was also some