426 B. B. Fand et al.
Within Year Variability of Pest
Population
Daily weather station data from two locations
across the cotton growing zones of India, viz.,
Ludhiana (Punjab) and Akola (Maharashtra) were
used to predict seasonal variability in P. solenop-
sis population growth and abundance. In India,
cotton is sown around May–June and harvested
around October–December in different parts of
the country; however, wide range of flora pres-
ent abundantly throughout the year supports the
carryover and perpetual of P. solenopsis during
off seasons (Vennila et al. 2010 , 2011 ). Accord-
ing to the analysis, in both selected locations P.
solenopsis populations potentially might increase
with a maximum finite rate of about 1.16 during
the total cropping season and reduced to 1.0 dur-
ing off season and cool winter months (Fig. 8a
and 8b).
However, the population growth potential
varied considerably among the seasons (crop-
ping and off seasons) and across the agroclimatic
zones, which might be due to larger within year
temperature fluctuations and also differences in
sowing dates of the crop. According to the model
predictions, at Ludhiana, P. solenopsis activity
is considerably high throughout the entire crop
season with peak infestation during June–August
(Fig. 9a). Contrarily, the pest is predicted to have
maximum finite rate of increase during of April–
May at Akola (Fig. 9b). The temperature increaseFig. 4 Life table parameters of P. solenopsis estimated through model prediction over a range of temperatures: a net
reproduction rate ( R0), b mean generation time ( T), and c finite rate of increase ( (^) λ ) /