On the bionomics of Aphidius matricariae Hal., a braconid parasite of Myzus persicae Sulz

Abstract

1. Aphidius matricariae Hal. is an internal parasite of Myzus persicae Sulz.; it was also found parasitizing M. circumflexus Buckt. and Aulacorthum solani Kalt. (Myzus pseudosolani Theob.).2. The percentage of aphides successfully parasitized increased with an increased number of strikes per host. A single female can lay up to 350 eggs, and one female successfully parasitized 309 M. persicae.3. The female parasite reaches its maximum activity during the 2nd or 3rd day of oviposition, and this activity has no correlation with light intensity.4. The disappearance of supernumerary larvae due to cannibalism has been observed.5. The species is arrhenotokous. Mating takes place from 2 hr. after emergence. In the progeny of early matings the females preponderated; in later matings the sex ratio was approximately 1:1.6. The parasite appears to fly under the same conditions as those generally favourable for aphides. It is generally disseminated by flight of the adult itself and through localized movements of parasitized apterous aphides.7. The host is unable to reproduce if ‘struck’ in the 3rd instar or earlier.