International Journal of Horticulture 2015, Vol.5, No.4, 1
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pest optimal growth during July- September. So, the
wild form,
S. pinnata
, may be used as trap crop which
are obviously more attractive and can lure insects
away from the main crop for better production of
hog-plum. Ultimately, the Knowledge on their
population growth parameters as well as their
nutritional ecology in relation with respective host leaf
chemical regime will enable growers to employ the
most appropriate control tactics towards integrated
crop management (ICM) of hog-plum plants.
3 Materials and methods
3.1 Plant materials
The hog-plum (
S. dulcis
and
S. pinnata
) leaves (tender
and mature) were collected randomly from different
places of Hooghly (22°53' N, 88°23' E), West Bengal,
India. Leaves were initially rinsed with distilled water
and dried by paper toweling for phytochemical
analysis.
3.2 Extraction and phytochemical estimation
The freshly harvested
S. dulcis
and
S. pinnata
leaves
were dipped in different solvents for extraction of
different primary and secondary chemicals. Finally,
the variability of the phytochemicals present in the
two host plant leaves were estimated by various
biochemical analysis, such as total carbohydrates
(DuBois et al.,1956), total proteins (Miller, 1959),
total lipids (Folch et al., 1957), total amino acids
(Moore and Stein, 1948), total nitrogen (Humphries,
1956), moisture (Banerjee and Haque, 1984), total
phenols (Bray and Thorpe, 1953), total flavonoids
(Zhishen et al., 1999), tannin ( Trease and Evans,
1983), saponin (Trease and Evans, 1983), alkaloid
(Harborne, 1973), phytate (Reddy and Love, 1999)
and oxalate (Day and Undrwood, 1986). Each
biochemical analysis was repeated for three times and
expressed in dry weight basis.
3.3 Insect rearing
The insects used in this study were collected by sweep
netting from the respective host plants. The insects
were maintained separately in 1 l glass jars, containing
respective host leaves, and covered with fine-mesh
nylon nets at 27±1°C temperature, 65±10% relative
humidity, and a 12L: 12D photoperiod in a BOD
incubator. The F2
P. quatuordecimpunctata
were used
for oviposition separately in different sterilized glass
jars. Fresh leaves were given daily by replacing the
previous one until eggs were laid by the test insects,
and the eggs with each host-plant leaves were placed
in new sterilized glass jars separately. To maintain
natural condition of leaves, a moist piece of cotton
was placed around the cut ends of leaf bearing twigs
followed by wrapping with aluminum foil to prevent
moisture loss. To study their life table parameters, the
eggs were separated and checked daily until all eggs
either hatched or collapsed, and the numbers of daily
emerged larvae along with their survival and
developmental time were recorded by daily
monitoring. The larvae and adults were reared in
sterilized glass jars containing 20 individuals on each
kind of host leaves for study their feeding dynamics
with five replicates for each host plants. Thus, the
feeding dynamics along with different life table
parameters of
P. quatuordecimpunctata
were
determined by a single generation with three cohorts
for each kind of host leaves.
3.4 Food utilization
The weight gain of insects, the weight of food
consumed and the weight of faeces produced were
determined in a monopan microbalance (±0.01 mg).
Third generation larvae of approximately same size
were selected and weighed initially and were reared
separately into separate sterilized glass jars. They
were allowed to feeding on weighed quantity of two
types of host leaves for 24 h and were reweighed. The
fresh weight gain during the period of study was
estimated by determining the differences in weight of
larvae or adults. The quantity of the food consumed
was estimated by determining the difference between
the dry weight of diet remaining at the end of each
experiment and total dry weight of diet initially
provided. All the values were expressed on dry weight
basis through dry conversion values as described by
Roy and Barik (2013) and Roy (2014). Twenty
individuals were used in each type of host leaves for
each instars and adults with five replicates.
3.5 Food utilization indices calculation
Food utilization indices (on dry weight basis) were
calculated by the formulas of Waldbauer (1968) with
slight modifications (Thangavelu and Phulon, 1983;
Sétamou et al., 1999; Xue et al., 2010; Roy and Barik,
2012; 2013) to assess the feeding efficiencies of
P.
quatuordecimpunctata
. All the feeding indices like,
growth rate (GR), consumption rate (CR), relative
growth rate (RGR), consumption index (CI), egestion
rate (ER), host consumption rate (HCR), approximate
