Effects of temperature and host plant on the biological parameters of Aphidius transcaspicus Telenga (Hymenoptera: Braconidae)

The performance of the parasitoid species Aphidius transcaspicus Telenga on Hyalopterus amygdali Blanchard as the aphid host has been evaluated through a no-choice test. The experiments were carried out by measuring the prepupal and preimaginal development times, parasitism rate, emergence rate and sex ratio under controlled conditions. The effects of three constant temperatures between 20 and 27 degrees C (+/- 1 degrees C) and two host plants (almond tree, Prunus dulcis-winter host and reed, Phragmites communis-summer host) have been assessed. The results indicated that the highest prepupal (16.85 +/- 0.293 days) and preimaginal (30.65 +/- 0.254 days) development times appeared at 20 degrees C on P. communis and the lowest ones were also shown on the same host plant at 27 degrees C. In addition, the highest parasitism rate was observed on almond (62.78 +/- 4.43% at 24 degrees C) while the lowest occurred on P. communis (30.38 +/- 4.86% at 24 degrees C). The highest emergence rate was observed at 20 degrees C on P. communis (73.66 +/- 5.03%) and on almond (61.64 +/- 5.58%) whereas the lowest appeared at 27 degrees C on P. communis (27.50 +/- 3.45%). Furthermore, the sex ratio was biased in favor of females on almond (0.360 +/- 0.036 at 24 degrees C). However, it was slightly biased in favor of males on P. communis (0.547 +/- 0.035 at 24 degrees C). Thus, the most favorable host plant and temperature for the development and multiplication of A. transcaspicus on H. amygdali was obviously almond tree and 24 degrees C (+/- 1 degrees C) respectively, among the tested plants and temperatures. Hence, these encouraging results could lead to carry on a release of this parasitoid in almond orchards.