1. Correlation co-efficient (r)
RELATIONSHIP OF RED PUMPKIN BEETLE, Aulacophora foveicollis (Lucas) INFESTING PUMPKIN WITH WEATHER PARAMETERS
S. T. RATHOD., P. K. BORAD and V. S. JILU
Department of Entomology, Anand Agricultural University, Anand (Gujarat), India
Introduction:
India is the second largest producer of vegetables next to China. Among the different groups of vegetables, the cucurbits form an important and big group of vegetable crops cultivated extensively in India. Pumpkin is an important nutritious cucurbitaceous vegetable used all over the world. Aulacophora foveicollis (Lucas) commonly known as red pumpkin beetle is the widely distributed and most serious pest of pumpkin. Grubs of this beetles feed on roots and underground portion of pumpkin and also fruits touching the soil. The beetles injure the cotyledons, flowers and foliage by biting holes into them. The affected underground parts start rotting due to secondary infection by fungi, bacteria etc.
Materials and Methods:
To know the population dynamics of A. foveicollis in relation to different weather parameters, the field experiment was carried out during the kharif (2004) and summer (2005) season at Vegetable farm of AAU, Anand. Pumpkin was sown in  12 m area in 1st week of July during kharif season of 2004 and 1st week of February during summer This whole area was divided into five equal quadrates. From each quadrate, five plants were selected randomly for recording the observations and numbers of adult beetles were recorded from each selected plant at weekly interval starting from one week of germination till end of crops.
The data on population were further correlated with abiotic factors to determine its effect on fluctuation of A. foveicollis population.
Results:
In kharif activity of A. foveicollis initiated on pumpkin crop from 2nd week of July. Pest activity reached peak level on 4th week of August (Fig. 1). In summer pest activity was recorded from February which gradually increased and reached at peak level on 4th week of March (Fig. 2). Then the pest activity decreased gradually.
The correlation coefficient results (Table 1) revealed that among the abiotic factors, VP and RH were significantly positively correlated with A. foveicollis activity on pumpkin during kharif. During summer, temperature had significantly positive association whereas, relative humidity was significantly negatively correlated with A. foveicollis incidence on pumpkin.
Fig. 1: Population dynamics of A. foveicollis on pumpkin (Kharif, 2004)
Table 1: Correlation co-efficient between abiotic factors and A. foveicollis activity on pumpkin
Weather parameters
Correlation co-efficient (r)
Kharif (2004)
Summer (2005)
Temperature (oC)
0.197
0.593*
Relative humidity (%)
0.494*
-0.597**
Vapour pressure (mm)
0.695**
-0.324
Sunshine (hrday-1)
-0.221
-0.040
Rainfall (mm)
-0.027 -
Wind speed (Kmph-1)
-0.102
-0.294
* Significant at 5 % level ** Significant at 1 % level
Fig. 2: Population dynamics of A. foveicollis on pumpkin (Summer, 2005)
Conclusion:
Activity of A. foveicollis and different weather parameters were recorded from July to November in kharif 2004 and February to June in summer Pest activity reached peak level on 4th week of August in kharif and 4th week of March in summer. The relative humidity and vapour pressure had significantly positive relationship with pest activity during kharif. Temperature and relative humidity had significantly positive and negative relationship, respectively with pest activity during summer.