Biology of Conchyloctenia hybrida (Coleoptera: Chrysomelidae: Cassidinae) on Solanum campylacanthum subsp. panduriforme

The biology of the afrotropical Conchyloctenia hybrida Boheman on Solanum campylacanthum subsp. panduriforme was studied under laboratory conditions in South Africa. Papery oothecae contained between 2 and 10 eggs. Adults displayed vigorous feeding, high fertility, longevity, as well as careful choice of oviposition site. Construction of oothecae was highest at the junctions of main and lateral veins on abaxial leaf surfaces facing upwards or downwards and adaxial surfaces facing downwards. The period from oviposition to adult eclosion ranged between 37 and 42 d at 25°C. Adults had an even sex ratio. After a preoviposition period of 34 d, females deposited 3 to 48 oothecae in 4 to 91 d. The mean longevity of females and males was 168 and 165 d, respectively. The net replacement rate was 50.14, the intrinsic rate of natural increase was 0.97 per month, the mean generation time was 4 mo, and doubling time was 0.71 mo. Daily consumption rate of leaves increased rapidly in late larval instars and was highest for adults. Adults underwent a series of elytral color changes corresponding with age and physiological state. Mature adults characterized by hardened metallic-colored elytra had a higher winter survival rate than young adults with soft, nonmetallic elytra.