Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

232 Biological Control of Insect Pests: Southeast Asian Prospects
larva was found in 66% of hosts. Small, dead, damaged parasitoid larvae in
some hosts provided evidence that there was competition for survival
(Liljesthršm 1993b).
Because moulting led to loss of unhatched eggs with the discarded
cuticle, eggs laid on nymphs less frequently led to successful parasitisation
than eggs laid on adults. With 1 parasitoid egg per adult, success was greater
on males than on females whereas, when more than 4 eggs were present, the
success rate was higher with females (Liljesthršm 1991). T. giacomellii
parasitised 100% of N. viridula adults for 3 consecutive generations in an
uncultivated area near Buenos Aires (Liljesthršm 1981) and it was
concluded that T. giacomellii could regulate the population of N. viridula
(Liljesthršm and Bernstein 1990).
T. giacomellii (at times referred to incorrectly as Eutrichopodopsis
nitens) is also an important parasitoid of N. viridula in Brazil. When
parasitisation occurred in nymphs or newly moulted adults, adults did not
reproduce and longevity was greatly reduced. Female N. viridula,
parasitised on the 7th day of the adult stage, had their fecundity reduced by
58%, but neither egg fertility nor size was affected (Ferreira et al. 1991).
Parasitisation by T. giacomellii collected in the field in Brazil from soybean
and other crops ranged from 27.1% to 52.7%. More parasitised eggs were
found on males than on females and most eggs were on the thorax (Ferreira
1984). High rates of parasitisation of N. viridula by T. giacomellii were
observed on the weed Leonurus sibericus, but populations transferred to
nearby soybean when this entered the reproductive phase. On the other hand,
bugs living on castor, Ricinus communis, stayed on this plant all year round.
This weed is of low nutritional value to them, but on it they are less liable to
attack by the tachinid (Panizzi 1989).
A recent laboratory study of the reproductive attributes of T. giacomelli
determined the influence of adult food availability and body size on
fecundity, and longevity, both relevant to any introduction program
(Coombs 1997).
Little is known about other Trichopoda species attacking pentatomid
bugs: T. lanipes in Florida (Drake 1920), Trichopoda sp. in Uruguay (Guido
and Ruffinelli 1956) and possibly other species in Brazil (Jones 1988).
Bogosia antinorii
This species is widespread in eastern and southern Africa and is known only
from N. viridula (van Emden 1945; Barraclough 1985). There was
apparently an unsuccessful attempt to establish it in Australia from material
from Kenya (Greathead 1971).