Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

68 Biological Control of Insect Pests: Southeast Asian Prospects
RƒUNION
A. craccivora is parasitised by Aphidius colemani on Gliricidia maculata
and by Aphelinus sp. on Vigna unguiculata. In turn Aphelinus sp. is
parasitised by Syrphophagus africanus and Pachyneuron vitodurense.
A. craccivora is also attacked by the coccinellid predators Scymnus
constrictus and Platynaspis capicola (Quilici et al. 1988).
SHANGHAI
The main parasitoids of A. gossypii on cotton were Trioxys communis,
T. rietscheli and Lipolexis gracilis. Next in importance was Aphidius
gifuensis, and there was occasional attack by Aphelinus abdominalis and
A. mali. The highest total parasitisation recorded was about 27%. Parasitoids
constituted 22.7% of the emergences from aphid mummies and the
hyperparasitoids Syrphophagus aphidivora 45.2%, Alloxysta sp. 15.1%,
Pachyneuron aphidis 14.7% and Dendrocerus 2.3%. The number of
parasitoids only exceeded that of hyperparasitoids during the first half of
August (Shi 1980, 1987).
TONGA
Aphidius colemani and Lysiphlebus testaceipes were introduced from
cultures in Czechoslovakia for the biological control of the banana aphid
Pentalonia nigronervosa (Stechmann and Všlkl 1988, 1990; Všlkl et al.
1990), but there is no indication that they became established. A. colemani
from a culture originating from a garden in Canberra was introduced again in
1990 and recovered in 1992 from Aphis gossypii on taro, but not from the
banana aphid. The further introduction of Aphidiidae, which are obligate
parasitoids of aphids, was recommended since they could assist in the
control of pest aphids and not pose a threat to non-target insects (Carver et al.
1993). Although 15 aphid species are recorded in Tonga including
A. craccivora, by 1993 no aphids other than A. gossypii had been recorded
as hosts of A. colemani, although recent monitoring has not been possible.
Two other primary parasitoids were recorded, Aphelinus gossypii (from
Aphis gossypii) and Lipolexis scutellaris, from a single female, free on a
banana sucker (Carver et al. 1993; Wellings et al. 1994).
Three common and widespread aphid predators were recorded (the
syrphid Ischiodon scutellaris, the coccinellid Harmonia octomaculata and
the hemerobiid Micromus timidus) in addition to 11 tramp species of ants
(Carver et al. 1993).