Biological Control of Insect Pests: Southeast Asian Prospects - EcoPort

4.4 Aphis gossypii 77
as attacking L. testaceipes breeding in Rhopalosiphum maidis, an important
virus vector on sugarcane (Timberlake 1927). According to Starù (1970), the
introductions were partially to substantially effective, but importation of
additional species was recommended. L. testaceipes from Cuba was
introduced to Czechoslovakia for the biological control of aphids in
greenhouses and also of some pest aphids in some subtropical areas (Starù
1970). L. testaceipes was introduced in 1956 and 1960 from Hawaii to the
Philippines, but no recoveries have been recorded (Baltazar 1963).
L. testaceipes was introduced in 1973 from Cuba into France and Corsica
(Italy) to reduce the numbers of citrus aphids (Starù et al. 1988b). It became
well established, heavily parasitising Aphis gossypii and several other aphids
(Rabasse 1986).
Although there do not seem to be comparable data for A. gossypii, Hall
and Ehler (1980) found that L. testaceipes averaged 79.5% parasitisation of
Aphis nerii populations on oleander, with an average density of 12.4 aphids
per shoot. When natural enemies were excluded, an average of 32.6 aphids
were present per shoot, a clear indication that parasitisation was having a
significant effect. A hyperparasitoid Pachyneuron sp. was active, but
appeared to be generally unimportant in aphid population regulation. The
average fecundity of L. testaceipes was found to be 128.2 eggs at 20¡C and
180 eggs at 25¡C. Development from egg to female adult was completed in
12.9 days at 20¡C and 9.5 days at 25¡C; and the life span of females was 2.7
and 2.6 days at 20 and 25¡C respectively. At 20¡C the intrinsic rate of
increase was slightly lower than that of Aphis gossypii, but was the same at
25¡C. It was concluded that, at temperatures below 25¡C, L. testaceipes
might not be able to overtake an established population of A. gossypii (van
Steenis 1994). Earlier Schlinger and Hall (1960) concluded that
L. testaceipes was capable of producing excellent control of both
A. craccivora and A. gossypii.
Praon volucre Hym.: Aphidiidae
This is a palearctic species and is known from the Middle East, North Africa,
India and Central Asia. It has an extensive and diverse host range, having
been recorded from at least 90 aphid species in 35 genera. There is good
evidence that P. volucre exists as a complex of host-specific biotypes or
sibling species (Mackauer 1959, 1962a,b). Its biology has been studied by
Beirne (1942). As in other Praon spp., pupation takes place under the empty
mummy of the parasitised host. P. volucre females have been observed to
use their front legs to hold the host aphid during oviposition (Beirne 1942).
Although it has been recorded from A. craccivora in the field (Starù 1967a)
and the laboratory (Carver 1984), it does not seem to have been reported
from A. gossypii.