Comparative biology and life tables of Trichogramma aurosum on Cydia pomonella at constant temperatures

Phytoparasitica (Impact Factor: 0.9). 04/2011; 39(2):109-119. DOI: 10.1007/s12600-010-0142-4


The influence of constant temperatures on biological parameters of German strains of Trichogramma aurosum Sugonjaev & Sorokina (Hymenoptera: Trichogrammatidae) was evaluated in the laboratory on eggs of Cydia pomonella L. (Lepidoptera: Tortricidae). Development time and longevity of all strains were decreased as temperature increased. Development
time of the strains differed significantly only when exposed to 15°, 20°, and 25°C. Cumulative fertility and longevity differed
significantly at 15° and 20°C. Realized fertility differed significantly at all constant temperatures. Emergence rates of
all strains were less than 65% and were decreased even further as temperature increased. Female-biased sex ratio ranged from
65% to 100% at all constant temperatures. The low temperature threshold for T. aurosum was 10°C and the mean number of degree-days at 15°, 20°, 25° and 30°C was 175, 183, 173 and 185, respectively. The Bavarian
strain tolerated high temperatures and had the highest parasitization capability, while the Hessian strain had the lowest
parasitization at all temperatures. Fertility life table analysis revealed a major effect of temperature on the population
growth parameters. Net reproductive rate was highest at intermediate constant temperatures in all strains, with the highest
rate recorded for the Bavarian strains at all constant temperatures. Mean cohort generation time, and population doubling
time decreased as temperature increased. The daily intrinsic rate of increase and finite rate of increase were positively
correlated with temperature. The relevance of our results is discussed in the context of climatic adaptation, intraspecific
variability and biological control.

KeywordsCodling moth–Cumulative fertility–Development time–Egg parasitoids–
Ephestia kuehniella
–Intrinsic rate of increase–Life time fertility–Longevity–Sex ratio

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