Effect of Coleus size and variegation on attack rates, searching strategy, and selected life history characteristics of Cryptolaemus montrouzieri (Coleoptera: Coccinellidae).
The effect of Coleus blumei variegation (green or yellow plants), plant size, plant height, leaf number and leaf area, and prey density on the attack rates and search strategy of 3rd-instar Cryptolaemus montrouzieri using Planococcus citri as prey was studied in 24-h laboratory tests. In a separate experiment, individual 3rd-instar Cryptolaemus montrouzieri were fed 10 or 1 P. citri prey daily, or 1 prey organism every 2 days, and the effect on life history parameters was investigated. None of the plant parameters significantly affected predator attack rates. Increasing prey density on plants significantly increased the attack rate, which reached a plateau of approximately 3.5-4.0 prey attacked on plants containing 16 prey individuals. There was an inverse relationship between prey density and the estimated area searched. Cryptolaemus montrouzieri development was slower, and survival and 4th-instar and adult body weight was lower when provided with few prey. However, the sex ratio was unaffected.