CHAPTER I INTRODUCTION
3. Study related indicators
4.3.5. Relationship between weather factors and mean grading index (MGI)
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(50.96%) and follows grade-4 (27.56%), grade-3 (15.03%), grade-2 (4.48%) and grade-1 (1.98%).
In average, South-West region of Bangladesh in the month of June, 2017, coconut nut infestation by coconut mite at grade-5 was high (44.60%) and follows grade-4 (28.90%), grade-3 (19.16%), grade-2 (6.26%) and grade-1 (1.09%).
In terms of mean grading index in the month of June, 2017, Jassore region showed the high value 4.40 and follows Satkhira region 4.11, Barisal region 3.89, Bagerhat region 3.61 and the South- West region of Bangladesh 4.00.
Table 4.3.12. Damage index of eriophyid mite in different coconut growing districts in June, 2017
Districts Upazila G-1 (%
infestati on)
G-2 (%
infestat ion)
G-3 (%
infestati on)
G-4 (%
infestat ion)
G-5 (%
infestati on)
Mean grading index Jassore Jassore Sadar 0.00 6.59 46.15 32.97 14.29 4.42
Bagherpara 0.00 7.79 19.48 35.06 37.67 4.38
District Average 0.00 7.19 32.82 34.02 25.98 4.40
Satkhira Mongla 0.65 7.24 15.13 26.32 50.66 4.18
Chitolmari 0.70 0.00 16.20 26.76 56.34 4.03
District Average 0.68 3.62 15.67 26.54 53.50 4.11
Barishal Barishal Sadar 1.66 4.17 9.17 20.83 64.17 3.92
Uzirpur 1.77 15.29 17.06 34.12 31.76 3.87
District Average 1.72 9.73 13.12 27.48 47.97 3.89
Bagherhat Kolaroa 1.77 5.31 13.27 35.40 44.25 3.70
Kaligonj 2.19 3.65 16.79 19.71 57.66 3.52
District Average 1.98 4.48 15.03 27.56 50.96 3.61
Grand Average 1.09 6.26 19.16 28.90 44.60 4.00
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became high then mean grading index became low. From the figure, rainfall was increased after the month June, 2017 and decrease at the month of December, 2016. At that time, the mean grading index remained high at the month of June, 2017 and after the rainy season it became low at the month of September, 2016. Again when rainfall decreased i.e. after December, 2016 then the mean grading index increased. We can conclud that, the mean grading index became low after rainy season and increased at winter season.
4.3.5.2. Relationship between weather factors and MGI of Jassore region
Relationship between weather factors like average temperature, rainfall and relative humidity and mean grading index of Jassore region is shown in figure 4.3.2. From the figure it is observed that, the mean grading index was gradually increased from the month September, 2016 to June, 2017.
Here it clearly demostrated that, rainfall had negative effect on mean grading index i.e. when the rainfall became high then mean grading index became low. From the figure, rainfall was increased after the month June, 2017 and decreased at the month of December, 2016. At that time, the mean grading index remained high at the month June, 2017 and after the rainy season it became low at
3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2
0 20 40 60 80 100
Sep./16 Dec./16 Mar./17 Jun./17 M
ean Grading Index (MGI)
Weather data
Different months
Figure 4.3.1. Relationship between weather factors and MGI of South-West region of Bangladesh
MGI Av. Temp. Rainfall R.H.
132
the month September, 2016. Again when rainfall decreased i.e. after December, 2016 then the mean grading index increased. We can conclud that, the mean grading index became low after rainy season and increased at winter season.
4.3.5.3. Relationship between weather factors and MGI of Satkhira region
Relationship between weather factors like average temperature, rainfall and relative humidity and mean grading index of Satkhira region is shown in figure 4.3.3. From the figure it is observed that, the mean grading index was gradually increased from the month September, 2016 to June, 2017.
Here it clearly revealed that, rainfall had negative effect on mean grading index i.e. when the rainfall became high then mean grading index became low. From the figure, rainfall was increased after the month June, 2017 and decreased at the month of December, 2016. At that time, the mean grading index remained high at the month June, 2017 and after the rainy season it became low at the month September, 2016. Again when rainfall decreased i.e. after December, 2016 then the
3.9 4 4.1 4.2 4.3 4.4 4.5
0 10 20 30 40 50 60 70 80 90
Sep./16 Dec./16 Mar./17 Jun./17
Mean Grading Index (MGI)
Weather data
Different months
Figure 4.3.2. Relationship between weather factors and MGI of Jeshore region
MGI Av. Temp. Rainfall R.H.
133
mean grading index increased. We can conclud that, the mean grading index became low after rainy season and increased at winter season.
4.3.5.4. Relationship between weather factors and MGI of Barishal region
Relationship between weather factors like average temperature, rainfall and relative humidity and mean grading index of Barishal region is shown in figure 4.3.4. From the figure it is observed that, the mean grading index was gradually increased from the month September, 2016 to June, 2017.
Here it clearly revealed that, rainfall had negative effect on mean grading index i.e. when the rainfall became high then mean grading index became low. From the figure, rainfall was increased after the month June, 2017 and decreased at the month of December, 2016. At that time, the mean grading index remain high at the month June, 2017 and after the rainy season it became low at the month September, 2016. Again when rainfall decreased i.e. after December, 2016 then the mean grading index increased. We can conclud that, the mean grading index became low after rainy season and increased at winter season.
3.3 3.4 3.5 3.6 3.7 3.8 3.9 4 4.1 4.2 4.3
0 10 20 30 40 50 60 70 80 90
Sep./16 Dec./16 Mar./17 Jun./17
Mean Grading Index (MGI)
weather data
Different months
Figure 4.3.3 Relationship between weather factors and MGI of Satkhira region
MGI Av. Temp. Rainfall R.H.
134
4.3.5.5. Relationship between weather factors and MGI of Bagerhat region
Relationship between weather factors like average temperature, rainfall and relative humidity and mean grading index of Bagerhat region is shown in figure 4.3.5. From the figure it is observed that, the mean grading index was gradually increased from the month September, 2016 to June, 2017. Here it clearly demonstrated that, rainfall had negative effect on mean grading index i.e.
when the rainfall became high then mean grading index became low. From the figure, rainfall was increased after the month June, 2017 and decreased at the month of December, 2016. At that time, the mean grading index remained high at the month June, 2017 and after the rainy season it became low at the month September, 2016. Again when rainfall decreased i.e. after December, 2016 then the mean grading index increased. We can conclud that, the mean grading index became low after rainy season and increased at winter season.
3.3 3.4 3.5 3.6 3.7 3.8 3.9 4
0 10 20 30 40 50 60 70 80 90
Sep./16 Dec./16 Mar./17 Jun./17
Mean Grading Index (MGI)
Weather data
Different months
Figure 4.3.4. Relationship between weather factors and MGI of Barisal region
MGI Av. Temp. Rainfall R.H.
135
0 0.5 1 1.5 2 2.5 3 3.5 4
0 10 20 30 40 50 60 70 80 90
Sep./16 Dec./16 Mar./17 Jun./17
Mean Grading Index (MGI)
Weather data
Different months
Figure 4.3.5. Relationship between weather factors and MGI of Bagerhat region
MGI Av. Temp. Rainfall R.H.
136
Experiment 4: Test on the action of chemical pesticides against coconut mites in laboratory condition
This study was conducted during February to March 2017 in the laboratory under Entomology Division of RARS, BARI, Jassore as well as in the laboratory under the Department of Entomology, SAU, Dhaka to determine the bioassay of chemical pesticides against coconut mites.
For this study detail sub-headings are given bellow: