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Key words. Aphididae, Macrosiphum euphorbiae, Braconidae, Praon volucre, parasitoid, fecundity, immature mortality, developmental time, biological control, intrinsic rate of population increase
Abstract. Life table data of natural enemies are often used to understand their population dynamics and estimate their potential role in the biological control of pests. Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae) is an important pest of several crops and its intrinsic rate of population increase (r^sub m^) is 0.282 at 22°C. The life table parameters (immature mortality, developmental time, sex ratio of emerging adults, fecundity and longevity) of Praon volucre (Haliday) (Hymenoptera: Braconidae: Aphidiinae) parasitizing M. euphorbiae were estimated in a climatic chamber at 22 ± 1°C, RH 70 ± 10% and 12 h photophase. Immature mortality was 8.2%, developmental time of males and females was 13.9 and 14.4 days, respectively, and the sex ratio was 0.55 (= fraction of females). Parasitoid fecundity was 504 eggs and longevity 11 days. The net rate of reproduction (R^sub 0^) was 207.5 females and the intrinsic rate of population increase (r^sub m^) 0.281 females/female/day. The time for doubling the population (TD) was 2.45 weeks. P. volucre has a population growth rate similar to that of its host M. euphorbiae and might therefore be a good candidate for the biological control of this aphid.
INTRODUCTION
In the selection and evaluation of natural enemies, determination of population growth parameters is important for understanding their population dynamics. Life table fertility data provide an integrated view of these population biological characteristics under certain environmental conditions and life table fertility data can be used to estimate the potential of a biological control agent for reducing the abundance of a pest (Bellows et al., 1992). Life table fertility data can also be used to calculate the intrinsic rate of population increase (rm), which is an important selection criterion for identifying potential biological control agents (van Lenteren, 2009).
Aphids have a high reproductive capacity and short developmental time resulting in rapidly increasing populations, which make them important pests in several crops, both in the field and in protected cultivation (Bueno, 2005). The aphid Macrosiphum euphorbiae (Thomas) (Hemiptera: Aphididae) originates from North America, but is now distributed throughout most of the world. It is a polyphagous aphid that can damage more than 200 species...