Concentration 
(ppm)

Concentration    difference

No. of alive   larvae

No. of dead    larvae

Mean
death

 Mean death         x
Concentration difference

00 (control)

00 (check)

100

200

300

400

500

 

0

0

100

100

100

100

100

 

20

20

17

14

9

8

0

 

0

0

3

6

11

12

20

 

0

0

3.0

4.5

8.5

11.5

16.0

 

0

0

300

450

850

1150

1600

                                                                                                         Total                4350 

The LC50 value of the leaf extract of Calotropis procera for 48 h has been determined according to the arithmetic method of Karber (1931). The calculation was done as following:


LC50  = 500 – 217.5
LC50   = 282.5ppm
Table 2: LC50 value of the leaf extract of Calotropis procera for 48 h.