Journal of Tea Science Research. 2015, Vol. 5, No. 8, 1-7
5
concentration and processed separately in a mini CTC
machine. The samples were forwarded to a professional
tea taster for assessment of taint as positive or
negative and for organoleptic test. Leaf infusion,
liquor color, briskness, strength & creaming down
parameters were considered for organoleptic test and
standard score was as >34 being Excellent (E), 32~34
being Above Average (AA), 30~32 being Average (A)
and <30 being BelowAverage (BA) out of 50.
Statistical analysis
The experimental data were statistically analysed by
Completely Randomized Design (factorial CRD) and
Randomized Complete Block Design (RCBD) using
MSTAT statistical software in a microcomputer. The
results are expressed as Mean ± SE and data were
statistically analyzed by one-way ANOVA, with the
level of significance set at p<0.05. The mean values were
separated by Duncan’s Multiple Range Test (DMRT).
Results and Discussion
Laboratory bioassay of commercial biopesticides
against red spider mite in tea
Results revealed that all the tested biopesticides showed
toxic effect on red spider mite in tea and reduced mite
population significantly in laboratory condition. In
laboratory condition, Miticon showed the highest
(93.28%) toxic effect at 72 HAT followed by Karanza
(92.55%) against red spider mite where as Bio-Cawach,
Neemakar, Rescue and Torpedo exhibited pronounced
acaricidal action (89.78~91.67%) at 72HAT at the
concentration of 0.8 ml/L of water (Table 2). Similar
trend of toxicity was found at 24HAT & 48HAT. The
mortality was in a linear trend i.e. increasing with
increasing of time. The order of toxicity of the tested
biopesticides on adult red spider mite was
Miticon>Rescue>Neemakar>Karanza>Torpedo>Bio-
Cawach (Figure 1).
Table 2 Laboratory evaluation of some commercial botanical biopesticides against red spider mites infesting tea
Treatment
Dosage
Percent Mortality*
Mean
24 HAT
48 HAT
72 HAT
T
1
- Bio-Cawach
0.8 ml/L
64.28±1.04d
75.56±1.42e
90.31±1.22d
76.72±1.23d
T
2
- Karanza
1.0 ml/L
66.27±1.68c
78.84±1.03d
92.55±1.31b
79.22±1.34b
T
3
-
Miticon
1.0 ml/L
70.24±0.96a
80.20±1.38b
93.28±1.62a
81.24±1.32a
T
4
- Neemakar
1.0 ml/L
68.14±1.26b
79.43±2.06c
90.40±1.84d
79.32±1.72b
T
5
- Rescue
0.5 ml/L
69.98±1.32a
81.36±2.14a
91.67±2.22c
81.00±1.89a
T
6
- Torpedo
0.5 ml/L
62.86±1.47e
80.33±1.40b
89.78±2.01e
77.66±1.63c
Sx
1.346
1.263
1.126
1.624
Probability level
0.05
0.05
0.05
0.05
*Mean of three observations (30 adults/observation) HAT= Hours after treatment ±Standard error of means at a given concentration
Within column values followed by different letter(s) are significantly different by DMRT at p<0.05
Figure 1 Toxicity of different plant origin biopesticides against
red spider mite in laboratory
Field evaluation of commercial biopesticides
against red spider mite in tea
From the field evaluation, it was found that all the
biopesticides have acaricidal value to reduce the infestation of
red spider mite significantly. The highest (81.34%)
reduction in mite population was observed in Miticon
treated plot followed by Rescue treated plot (81.01%)
(Table 3). The lowest (74.07%) reduction was observed in
Bio-Cawach treated plot. In field condition, similar trend of
order of toxicity in respect of acaricidal activity i.e.
Miticon>Rescue>Neemakar>Karanza>Torpedo>Bi
o-Cawach was also found (Figure 2)
.
