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Bulletin #2424, Insecticide Resistance in Colorado Potato Beetles - Long Descriptions for Figures in Bulletin #2424

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Figure 2. Generalized process of insecticide resistance development.

Schematic depicts 4 green rectangles arranged in a square, linked by clockwise arrows. Beginning from the top left, the first rectangle is filled with beetle silhouettes (4 rows of 8 each for a total of 32), all of them white. Over the arrow joining the first rectangle with the second is a stylized image of the DNA double helix. Under the arrow is this caption: “The first individuals with reduced susceptibilty to a given insecticide appear as a result of a random mutation.” The second rectangle shows the same 32 beetle silhouettes, except that two of them are colored red and yellow. The arrow down from the second to the third rectangle has a spray nozzle on one side of it and this caption on the other: “All susceptible individuals are killed by the insecticide, leaving only resistant insects in the population.” The third rectangle contains only the two red and yellow beetles; no white beetles. The arrow pointing left from the third rectangle to the fourth has a photo of two beetles mating above it, and this caption below it: “Resistant individuals multiply, eventually becoming numerous enough to cause economically significant damage.” The fourth rectangle shows 32 beetles, but they are all colored red and yellow.

Figure 3. Cumulative number of insecticides to which resistance in the Colorado potato beetles has been reported (Arthropod Pesticide Resistance Database, 2007).

Rectangular chart contains data points connected by a line that trends upward at about a 45-degree angle The X-axis values at the bottom of the chart are labeled “Year of Reported Resistance,” and run from 1950 on the left to 2010 on the right, in ten-year increments. The Y-axis values up the left side are labeled “Cumulative Number of Chemicals” and run from 0 a the bottom to 60 at the top, in increments of 10. The data points are as follows:

Year Cum. # of Cases
1955 1
1960 2
1965 10
1974 16
1975 21
1980 28
1981 32
1984 34
1989 36
1992 38
1993 39
1997 40
2000 41
2003 49

Figure 4. Risk of insecticide resistance depends on management practices.

Figure depicts trapezoid with top and bottom lines parallel, the top line being longer and thus the top of the trapezoid being wider. Label below trapezoid reads “Low Risk” and label above trapezoid reads “High Risk.” Four phrases appear along the inside bottom of the trapezoid, above “Low Risk.” Each is topped by an arrow pointing up at a slight outward angle to a corresponding phrase at the inside top of the trapezoid, under “High Risk.” The following table conveys the pairing of the phrases:

Low Risk High Risk
Alternating applications of different insecticides Repeated applications of the same insecticide
Spraying based on an economic threshold Regular calendar-based spraying
Annual crop rotation Continuous potato crop
Spot and perimeter treatment Treatment of the whole field

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