The present study aimed to investigate the development, predation and reproduction of Exochomus quadripustulatus L. (Coleoptera: Coccinellidae) at alternating temperatures of 9/19 +/- 1 degreesC and 12/24 +/- 1 degreesC as well as constant 25 +/- 1 degreesC, feeding exclusively on eggs and nymphs of Pulvinaria regalis CANARD (Homoptera: Coccidae). Additionally, its coincidence with the prey in the city of Bonn was examined in 1995 and 1997, respectively. In the laboratory, the mean developmental duration of E quadripustulatus decreased significantly at increasing temperatures. It was 57.1 days at 9/19 degreesC and 44.7 days at 12/24 degreesC as well as 28.3 days at 25 degreesC. Duration of the 4(th) larval stage was always the longest. It took 17.3 days at 9/19 degreesC, 14.5 days at 12/24 degreesC and 9.0 days at 25 degreesC to complete this stage. Mean duration of the pupal stage was 16.2 days at 9/19 degreesC, 10.8 days at 12/24 degreesC and 7.5 days at 25 degreesC. The total number of R regalis eggs consumed by E quadripustulatus larvae decreased significantly with increasing temperatures. The predation was 44.4 mg (= 8698 eggs) at 9/19 degreesC and 43.1 mg (= 8451 eggs) at 12/24 degreesC as well as 40.2 mg (= 7882 eggs) at 25 degreesC. The mean weight of E quadripustulatus larvae increased steadily during the larval development irrespective of temperature, but decreased slightly prior to the pupal moult. The mean weight of pupae was 0.0119 g at 9/19 degreesC and 0.0125 g at 12/24 degreesC as well as 0.0107 g at 25 degreesC. Hibernating E quadripustulatus female female consumed 10. 13 mg of biomass in the form of P. regalis nymphs at 9/19 degreesC and 9.69 mg at 12/24 degreesC, respectively. Predation of the malemale was less with 2.78 mg biomass consumed at 9/19 degreesC and 2.95 mg at 12/24 degreesC. The food uptake by freshly hatched E quadripustulatus female female was significantly higher than the uptake by male male but it was less than the uptake by the overwintering female female . In total, freshly hatched female female consumed on average 9.94 mg at 9/19 degreesC and 8.66 mg at 12/24 degreesC, freshly hatched male male on average 5.65 mg at 9/19 degreesC and 5.61 mg at 12/24 degreesC. E quadripustulatus female female laid a mean total number of 96.8 +/- 53.7 eggs within a period of 36 days at 9/19 degreesC and 139.1 +/- 75.0 eggs at 12/24 degreesC in a period of 30 days. The coincidence of the different developmental phases of the predator and the prey could be observed in the field in 1995 as well as in 1997. E quadripustulatus adapted its life cycle to the climatically induced postponement in the development of A regalis observed in 1997. Due to the very good predation of larvae and adult E quadripustulatus on R regalis, the sufficient reproduction of E quadripustulatus while feeding exclusively on P. regalis and the coincidence with the prey observed on amenity trees in the city of Bonn, E quadripustulatus has to be considered as a promising predator of P. regalis.
