Cost:Benefit Analysis Chart for Second Generation European Corn Borer

Table 15. Cost:Benefit Analysis Chart for Second Generation European Corn Borer

____ egg masses/100 plants	÷ 0.91 (correction factor)	= ___ adjusted egg masses
____ adjusted egg masses	÷ 100 plants examined	= ___ egg masses/plant
____ days after 1st egg laid	& ____ egg masses/plant	= ___ larvae/plant^a
____ larvae/plant	X ____ yield loss/plant^b,c	= ___ total yield loss
____ total yield loss	X ____ expected yield (bu/A)	= ___ bushels loss/A
____ bushels loss/A	X ____ price/bu	= ___ loss/A
____ loss/A	X ____ proportional control^b	= ___ preventable loss/A
____ preventable loss/A	- ____ cost of control/A	= ___ profit(loss)/A
^{Cost:Benefit Ratio _________ Economic injury level __________}

See the section "Reaching a Management Decision with Economic Injury Levels and Economic Thresholds" in the publication "European Corn Borer Ecology and Management" for how to use this table.

These values are percentages expressed as proportions

Use 0.04 for pollen-shed corn, 0.031 for blister-stage corn, and 0.024 for dough-stage corn.

Example Calculation

24 egg masses/100 plants	÷ 0.91 (correction factor)	= 26.4 adjusted egg masses
26.4 adjusted egg masses	÷ 100 plants examined	= 0.264 egg masses/plant
10 days after first egg laid	& 0.27 egg masses/plant	= 2.40 larvae/plant^a
2.40 larvae/plant	X 0.04 yield loss/plant^b,c	= 0.096 total yield loss
0.096 total yield loss	X 135 expected yield (bu/A)	= 12.96 bushels loss/A
12.96 bushels loss/A	X $3.50 price/bushel	= $45.36 loss/A
$45.36 loss/A	X 0.67 proportional control^b	= $30.39 preventable loss/A
$30.39 preventable loss/A	- $15.00 cost of control/A	= $15.39 profit (loss)/A

Cost:Benefit Ration = $15.00÷ $30.39 = 0.49
(It would pay to implement control)

Economic injury level = 1.18 larvae per plant or ~0.13 egg masses/plant at 10 days after initiation of the egg laying period.