Differences in Flight Activity of Coleomegilla maculata and Hippodamia convergens (Coleoptera: Coccinellidae) Following Emergence, Mating, and Reproduction.

The flight activity of Coleomegilla maculata DeGeer and Hippodamia convergens Guerin-Meneville (Coleoptera: Coccinellidae) was examined by observing tethered beetles in the laboratory. C. maculata were fed eggs of Ephestia kuehniella Zeller, as were larval H. convergens, whereas adult H. convergens were fed Melanaphis sacchari (Zehntner) to induce egg maturation; adults of both species received water and diluted honey. A spot of magnetic paint was applied to one elytrum of each beetle, which then adhered to a small neodymium magnet attached to a thread. Beetles were permitted 1 h flight opportunities daily for 3-d periods, first as virgins on their fifth day of adult life, secondly after mating, thirdly after females began oviposition, and fourthly after prey were withheld and egg maturation and oviposition ceased. Both species exhibited low flight activity as virgins, and whereas C. maculata females increased their activity after mating, H. convergens females did not. Flight activity in C. maculata did not change with onset of oviposition, whereas it increased in H. convergens males, but not females. In contrast, H. convergens females increased their flight activity after cessation of oviposition, whereas C. maculata females did not. Female flight activity when either virgin or mated correlated weakly with fecundity in C. maculata, but not in H. convergens. Species differences are discussed in the context of nutritional ecology; H. convergens usually enters diapause immediately following emergence, and is more dependent on aphids for reproduction, whereas C. maculata develops and reproduces on a wider range of foods and is not so constrained.