Research Reports: Effects of Shape and Size of Colored Traps on Attractiveness to Irradiated, Laboratory-Strain Mexican Fruit Flies (Diptera: Tephritidae)

David C. Robacker


Twenty-four trap types representing all combinations of 4 colors, 3 shapes and 2 sizes were evaluated for visual attractiveness to irradiated, laboratory-reared Mexican fruit flies, Anastrepha ludens (Loew), released into a grapefruit orchard when 1-3 days old. Spheres and vertically oriented rectangular panels were not significantly different in attractiveness summed over spring, summer and autumn seasons. Horizontally oriented rectangles were much less attractive than spheres and vertical rectangles. Larger rectangles (13 by 18 cm) and spheres (13 cm diam.) were more attractive than smaller rectangles (10 by 13 cm) and spheres (8 cm diam.). Yellow, green and red were equally attractive summed over trap shapes, sizes and seasons. Red was less attractive than green in spring and summer but more attractive in autumn. Relative attractiveness of yellow compared to green was less affected by season. Overall, vertical rectangles were more attractive than spheres in spring while spheres were more attractive in autumn. In spring, red spheres were more attractive than vertical red rectangles while yellow and white rectangles were more attractive than yellow and white spheres. Traps in trees with mature grapefruit generally captured more flies than those in trees with only small, immature fruit. Small spheres were more attractive than small vertical rectangles to females in trees with small, immature fruit but were less attractive than small vertical rectangles in trees with mature fruit. Overall, the best traps were the large sizes of the 6 combinations of yellow, green and red spheres and vertical rectangles that captured 8 times as many flies as the least attractive traps.

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