Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

14 Biological Control of Insect Pests: Southeast Asian Prospects
Attempts at classical biological control
CHINA
GUAM
INDIA
A species of Trichogramma,
possibly T. australicum, (Nagarkatti 1973), has
been imported on two occasions (Table 4.1.2) to attack the eggs of pest
Lepidoptera, including Agrius convolvuli,
but the resulting impact on
populations of the sweet potato hawk moth is not recorded.
Table 4.1.2 Attempts at classical biological control of A. convolvuli
Species From To Year Result Reference
HYMENOPTERA
TRICHOGRAMMATIDAE
Trichogramma
?australicum
Trichogramma
?australicum
USA Indonesia before
1929
+ Leefmans 1929;
Nagarkatti 1973
Philippines Japan 1929 + Shibuya &
Yamashita 1936;
Nagarkatti 1973
In Fujian Province, A. convolvuli larvae were parasitised by Charops bicolor
(Ichneumonidae), Apanteles spp. (Braconidae) and eulophid wasps (Wu
1983).
A. convolvuli is a minor pest of sweet potato on Guam. When sweet potato
was intercropped with maize, A. convolvuli eggs were parasitised to the
extent of 70 to 100% by Trichogramma chilonis.
This parasitoid attacks the
eggs of a range of sphingids and noctuids, including Ostrinia furnacalis,
less
than 20% of whose eggs on maize were parasitised. A. convolvuli colonises
new sweet potato plantings as soon as cuttings strike and, by the 4th week,
30 to 60% of its eggs are parasitised. Each large egg produces 13±
7
parasitoids, which emerge about 10 days after the host egg is parasitised. It
was concluded that T. chilonis is a major mortality factor for the sweet potato
hornworm (Nafus and Schreiner 1986).
A. convolvuli is an occasional pest of sweet potato, Vigna mungo and Vigna
radiata.
Eggs are also laid on the leaves of Colocasia antiquorum and
Clerodendrum chinense,
but no significant feeding occurs on these latter
plants.
Four species of parasitoid attack the eggs of A. convolvuli near
Bangalore: Trichogramma australicum, T. achaeae, T. agriae and a species
of Telenomus (Eulophidae). The abundance of each parasitoid varied with
the plant species on which the eggs were laid. T. agriae was the commonest
species in eggs collected on Colocasia, followed by T. achaeae and