Minty Little Bugs

Just a quick note about a lovely little critter I found yesterday:

Kuschelina gibbitarsa, Gander Mt. FP, Lake Co, IL  5/29/2014

 This is Kuschelina gibbitarsa, one of the Flea Beetles in the family Chrysomelidae. He's a leaf-eater, and I'm afraid I interrupted his lunch. The beautiful color seems very appropriate -- this leaf (and indeed all the leaves he'll eat) is a mint. (Mints are actually quite common in much of North America.)

Many of these chrysomelids are specialist leaf eaters, existing on just a few plant species. Since they are also quite diverse and rather well-known, they've been used to examine theories of coevolution between plants and their herbivores. Futuyma & McCafferty did so with the genus Ophraella, and found no evidence for such coevolution. (1) They concluded that speciation in beetles didn't correlate well with speciation in the plants, and suggested that much of the diversification in beetles happened more recently than diversification with the plants. Farrell & Mitter looked at Phyllobrotica, and they found the opposite, that these beetles apparently diverged in parallel with their host plants. (2) This difference is a beautiful example of how difficult it is to find sweeping generalizations in a world full of history.

This dietary specialization also means that these beetles can be serious agricultural pests. Our usual response to such things is pesticides, which come with their own set of problems. As early as 1972, Tahvanainen & Root demonstrated that a successful alternative is to plant diverse plots of crops. (3) That doesn't work well with our large-scale modern agricultural techniques, but it does with small garden plots. Another possibility, of course, is to release predators of the beetles. Biever & Chauvin suggested stinkbugs, (4) while Hazzard & Ferro examined ladybeetles. (5) (Specifically Coleomegilla maculata, a species we looked at earlier.)

(1) Futuyma, D. J., & McCafferty, S. S. (1990). Phylogeny and the evolution of host plant associations in the leaf beetle genus Ophraella (Coleoptera, Chrysomelidae). Evolution, 1885-1913.

(2) Farrell, B., & Mitter, C. (1990). Phylogenesis of insect/plant interactions: have Phyllobrotica leaf beetles (Chrysomelidae) and the Lamiales diversified in parallel?. Evolution, 1389-1403.

(3) Tahvanainen, J. O., & Root, R. B. (1972). The influence of vegetational diversity on the population ecology of a specialized herbivore, Phyllotreta cruciferae (Coleoptera: Chrysomelidae). Oecologia, 10(4), 321-346.

(4) Biever, K. D., & Chauvin, R. L. (1992). Suppression of the Colorado potato beetle (Coleoptera: Chrysomelidae) with augmentative releases of predaceous stinkbugs (Hemiptera: Pentatomidae). Journal of Economic Entomology, 85(3), 720-726.

(5) HAZZARD, R. V., & Ferro, D. N. (1991). Feeding responses of adult Coleomegilla maculata (Coleoptera: Coccinellidae) to eggs of Colorado potato beetle (Coleoptera: Chrysomelidae) and green peach aphids (Homoptera: Aphididae). Environmental Entomology, 20(2), 644-651.