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Keywords
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biological control, parasitoid, mass release, aphid control, environmental condition
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Abstract
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The greenbug, Schizaphis graminum Rondani, is a cosmopolitan and polyphagous aphid widely distributed
in temperate regions. It is a major pest of cereal crops, particularly wheat. Diaeretiella rapae (M’Intosh) is
one of the most important biological control agents of aphids on crucifer and cereal plants. The reproduction
and demographic parameters of D. rapae were investigated at six constant temperatures (10, 15, 20, 25,
27.5, and 30 °C) on S. graminum cultured on wheat plants (var. Pishtaz). No development was observed at
30 °C. The parasitoid showed the highest value of mummified aphids per female at 20 °C (120.08). The
intrinsic rate of increase (r) was significantly higher (0.374 day-1) and lower (0.019 day-1) at 25 and 27.5 °C,
respectively. The shortest times for doubling and mean generation of parasitoid were resulted from 25 °C
(1.85 and 7.73 days, respectively). Based on the results, a range of 20 to 25 °C is the most suitable
temperatures for D. rapae population growth on S. graminum. These findings have potential implications for
integrated S. graminum management in wheat fields. In addition, using a temperature-controlled
environment is a vital component of mass rearing facilities for consistent rearing of natural enemies. Thus,
the current results can be used in mass rearing and mass release programs of D. rapae.
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