Biology Reference
In-Depth Information
1996). Similar impacts have been observed in other areas in India also (e.g. Sushilkumar
2000; Dhiman and Bhargava 2005; Jaipal 2007). Defoliation by the leaf-feeding beetle
Z. bicolorata
also resulted in the re-establishment of native vegetation (Jayanth and
Visalakshy 1996; Sridhara et al. 2005). However, information on the long-term impact
of defoliation by the leaf-feeding beetle
Z. bicolorata
in India is lacking. Though non-
target feeding by leaf-feeding beetle
Z. bicolorata
on sunflower crop was reported
(Kumar 1992; Chakravarthy and Bhat 1994, 1997; Chakravarthy et al. 1994, 1996), later
studies (Jayanth et al. 1993, 1997, 1998; Jayanth and Visalakshy 1994b; Swamiappan
et al. 1997a, 1997b; Bhumannavar et al. 1998; Withers 1998, 1999; Viraktamath et al.
2004; Patel and Viraktamath 2005) indicated that the chance of the leaf-feeding beetle
Z. bicolorata
becoming a pest of sunflower is negligible. No economic loss due to the
leaf-feeding beetle
Z. bicolorata
feeding on sunflower even at higher insect densities was
recorded in India (Kulkarani et al. 2000).
The stem-galling moth
E. strenuana
was not approved for field release in India
due to oviposition and larval feeding on niger and sunflower (
Helianthus annus
L.)
crops (Jayanth 1987b; Singh 1997).
Parthenium winter rust, though not intentionally released as a biological control
agent, has been reported in India (Bagyanarayana and Manoharachary 1997; Parker
et al. 1994), but the strains occurring in India do not appear to be widespread or
aggressive (e.g. Kumar and Evans 1995). Hence, host specificity of a highly virulent
isolate of the winter rust
P. abrupta
var.
partheniicola
from Mexico as a biological
control agent for parthenium is being explored (Kumar and Evans 1995). However,
there are no immediate plans to import this rust to India for further studies.
Inability to establish the seed-feeding weevil
S. lutulentus
in quarantine in India
using adults collected in Australia prevented further studies on the host specificity
of this agent there.
12.4.8.4 SouthAfrica
A biological control program on parthenium was initiated in 2003 (Strathie 2007).
The leaf-feeding beetle
Z. bicolorata
, the stem-boring weevil
L. setosipennis
, the
stem-galling moth
E. strenuana
and the summer rust
P. melampodii
(Ntushelo and
Wood 2007; Strathie et al. 2005) were prioritised for host-specificity tests, in view
of their potential impacts and suitability for local climatic conditions. A colony of
the leaf-feeding beetle
Z. bicolorata
was established in quarantine from adults col-
lected in Australia, and host-specificity tests are in progress with results indicating
a strong likelihood of release (Strathie et al. 2005). In South Africa, the stem-boring
weevil
L. setosipennis
colony was established in quarantine from adults collected
from yellow-flowering parthenium in Santiago del Estero and outside Metán in
Salta province in northwestern Argentina, and host-specificity tests are in progress
(Strathie et al. 2005). An attempt to establish a culture of the stem-galling weevil
E. strenuana
in quarantine did not succeed, likely due to low humidity, but it will
be imported from Australia again (Strathie et al. 2005).
