Lygus lineolaris (Heteroptera: Miridae) Population Dynamics: Nymphal Development, Life Tahles, and Leslie Matrices on Selected Weeds and Cotton

The influence of hosts upon the demography of Lygus lineolaris (Palisot de Beauvois) was examined by comparing vital rates among hosts, and with life tables, and Leslie age-class models. Nymphal development, survivorship, and sex ratio data were obtained from cohorts on cotton, green beans, and up to 12 weed hosts implicated as sources of immigration into cotton. Adult survivorship and fecundity data were obtained from cohorts on cotton and Erigeron annuus (L.) Persoon. Linear models for total or stage-specific nymphal development were not different among nine weed hosts and cotton; they extrapolate to a lower threshold of about 10°C. A truncated normal model from green beans resulted in an upper threshold of about 34°C and a curve breadth that suggests a temperature–generalist life strategy. The percentage of time per instar was influenced by the host. Nymphal survivorship was high on weed hosts but poor on cotton. The sex ratio was 1:1 and was not influenced by host. Adult survivorship and total fecundity was higher on cotton than E. annuus, but the net fecundity was higher on the weed. More eggs were deposited in cotton buds than other parts of the cotton plant except the terminal. Birth rates were similar on E. annuus and cotton, but the cohorts on cotton had a higher death rate and longer generation time. Thus, the intrinsic rate of increase on cotton was about half that on E. annuus. The stable-stage distribution was unaffected by host and was about 0.50, 0.40, and 0.10 for eggs, nymphs, and adults, respectively. Host influenced the time of convergence. These analyses suggest an r-selected life strategy.