Biology of Zygogramma suturalis (F.) (Col.: Chrysomelidae), an introduced biological control agent of common ragweed, Ambrosia artemisiifolia.
The biology of Zygogramma suturalis, introduced into China from Canada and the USSR in 1987 as a biological control agent of common ragweed (Ambrosia artemisiifolia), was studied in the laboratory and field in Beijing in 1987-88. The pest had 3 generations a year, overwintering in the adult stage. Adults resumed activity and began feeding in late April or early May. Adults of the 1st, 2nd and 3rd generations occurred in mid-late June, late July-early August and early-mid-September, resp. At 26±1°C, the average lifespan of the adult female and male was 82.5 and 67.8 days, resp. The mated females began ovipositing 16.5 days after emergence. Oviposition lasted for an average of 49.1 days with a mean of 394.5 eggs laid per female. The development period of the egg, larval and pupal stages was 5.0, 13.9 and 12.9 days, resp., at 26±1°C. The larval and pupal survival rates at 26±1°C and room temperature were above 66%.