Biology Reference
In-Depth Information
to AUD 1.25/ha/year for buffel grass and AUD 1.19/ha/year for the Queensland blue
grass (Adamson and Bray 1999). At today's value (April 2007), the return is much
higher, i.e. AUD 2.50/ha/year for buffel grass and AUD 2.40/ha/year for the
Queensland blue grass (Dhileepan 2007). With more than 170,000 km
2
of parthenium
infestation in Queensland, this will translate to an economic benefit of AUD 37 mil-
lion annually to the Queensland grazing industry. These benefits are in addition to the
saving of AUD 8 million annually in medical costs in treating allergic dermatitis and
asthma in property workers from infested areas (Page and Lacey 2006).
12.4.8.2 Ethiopia
The winter rust (
P. abrupta
var.
partheniicola
) was first reported in Ethiopia in
1997, and now it is known to occur there commonly in cool and humid areas at high
altitudes (1,500-2,500 m above mean sea level) where rainfall varies from 400 to
700 mm (Taye et al. 2002, 2004a). In Ethiopia, the winter rust significantly reduced
the plant height, number of leaves, number of branches and total biomass of parthe-
nium (Taye et al. 2004a). The leaf-feeding beetle Z.
bicolorata
will be imported
from South Africa into quarantine in Ethiopia in 2008 for further testing on native
and economically important plant species. The stem-galling moth
E. strenuana
is
not being considered for introduction into Ethiopia, in view of its potential to feed
on niger (
Guizotia abyssinica
(L.f.) Cass.), a major oil seed crop there.
12.4.8.3 India
In India, a biological control program against parthenium was initiated in 1983, and since
then only the leaf-feeding beetle
Z. bicolorata
has been introduced. It was introduced
from Mexico in 1984 in the Bangalore region, and it became established in the same year
(Jayanth 1987a; Jayanth and Bali 1994a; Jayanth and Nagarkatti 1987). However, its
population levels attained damaging levels only after 3 years (Jayanth and Visalakshy
1994a, 1996). Field releases continued in 15 states in India (Viraktamath et al. 2004), and
now after 20 years the beetle occurs in the majority of areas in India with parthenium
infestations, ranging from the tropical south to sub-Himalayan regions in the north
(Basappa 1997; Bhatia et al. 2005; Dhiman and Bhargava 2005; Gautam et al. 2005b,
2006; Gupta and Anil Sood 2002, 2005; Gupta et al. 2004; Jadhav and Ashok Varma
2001; Maninder et al. 1998; Pandey et al. 2001; Sarkate and Pawar 2006; Sharma and
Sujauddin 2006; Susilkumar and Bhan 1998; Uniyal et al. 2001), but not in the hot and
dry arid northwest region (i.e. Rajasthan State). It is unlikely that the leaf-feeding beetle
Z. bicolorata
will survive in this region, as the summer temperature exceeds 45°C, result-
ing in very high mortality among eggs, larvae and diapausing adults (Jayanth and Bali
1993a). Incidence of the leaf-feeding beetle
Z. bicolorata
has also been reported from the
Punjab region in Pakistan (Javaid and Shabbir 2007). The leaf-feeding beetle
Z. bicolor-
ata
caused 85-100% defoliation, resulting in up to 99.5% reduction in the parthenium
weed density in Bangalore region (Jayanth and Bali 1994a; Jayanth and Visalakshy
