Aphidiine and aphelinid parasitoids of four principal pest aphids on greenhouse vegetable crops in Japan, Aphis gossypii, Myzus persicae, Macrosiphum euphorbiae and Aulacorthum solani, were surveyed to find native parasitoids that would be useful as biological control agents. A total of 19 species (Aphidiinae: 13 species in 7 genera, Aphelinidae: 6 Aphelinus species) were confirmed as parasitoids of the four pest aphids from field collection and breeding experiments. Of these, six species (Lysiphlebus fabarum and 5 Aphelinus species) were new to Japan. In total, 145 tritrophic (parasitoid-host aphid-plant) relationships are reported. The principal aphidiine parasitoids were Lysiphlebus japonicus and Binodoxys communis on A. gossypii, Aphidius gifuensis and Diaeretiella rapae on M. persicae, and A. gifuensis on A. solani. There were no predominant species among the parasitoid spectrum of M. euphorbiae in Japan. Aphelinus gossypii, A. varipes, A. albipodus and A. asychis showed a high degree of suitability for Aphis gossypii, Aphis gossypii and M. persicae, M. persicae and M. euphorbiae, and all four principal pest aphids, respectively. A key to the parasitoid species associated with the four pest aphids in Japan is provided. The potential using the native parasitoids as biological control agents against the four pest aphids is discussed.
A European strain of Aphidius ervi shall be introduced into Japan for the control of Macrosiphum euphorbiae on greenhouse tomatoes. We compared this strain, which is originating from The Netherlands (EVP), with a native strain from Hokkaido, Northern Japan (SPR) in several characteristics. The percentage of parasitism of SPR and EVP was significantly different, when attacking three aphid species: 13% and 30% on M. euphorbiae on tomato, 68% and 93% on Acyrthosiphon pisum on broad bean and 10% and 42% on Aulacorthum solani on sweet pepper, respectively. SPR and EVP differed morphologically (in the colouration of the petiole) and in the esterase banding patterns. Furthermore, cross mating experiments showed that SPR and EVP are partially reproductively isolated from each other. Complete reproductive isolation is evident in the one direction cross (EVP females and SPR males).
A total of 58 clones of Aphis gossypii, collected from 21 species within 14 families of plants at 13 localities in Japan, were examined to assess interclonal variation in the sexual morph‐producing ability. From the response to short photoperiod (10L: 14D, 18 °C) the clones examined were classified into 4 life‐cycle forms: holocyclic (24 clones), intermediate (4), androcyclic (9) and anholocyclic (21). Holocyclic clones were terminated within a few generations after transfer to the short‐day condition by producing oviparae and males exclusively, whereas clones of the other 3 forms continued parthenogenetic reproduction, but intermediate and androcyclic clones produced not only viviparous females but also respectively oviparae and males, and males. Some differences were found in the life‐cycle form composition even in small samples from different host plants. Zusammenfassung Über interklonale Unterschiede bei Aphis gossypii Glover (Hom., Aphididae) binsichtlich der Bedeutung der Phutoperiode für das Hervorbringen von Geschlechtstieren Die interklonale Variation in bezug auf die Erzeugung von Geschlechtstieren wurde anhand von 58 Aphis gossypii‐Klonen untersucht. Die Läuse stammten von 21 verschicdenen Pflanzenarten aus 14 Familien und wurden in 13 verschicdenen Gebieten Japans gesammelt. Autgrund ihrer Reaktion auf Kurztagbedingungen (10L:14D; 18°C) wurden die Klone in 4 Lebenszyklus‐Formen unterteilt: holozyklisch waren 24, intermediär 4, androzyklisch 9 und anholozyklisch 21 Klone. Die holozyklischen Klone brachten wenige Generationen nach Beginn der Kurztagbedingungen ausschließlich Oviparae und Männchen hervor. Dagegen blieb bei den anderen 3 Formen die parthenogenetische Fortpflanzung erhalten, aber die intermediären und androzyklischen Klone brachten nicht nur vivipare Weibchen hervor, sondern zusätzlich auch Oviparae und Männchen bzw. nur Männchen. Sogar bei kleinen Stichproben konnten bei den verschiedenen Wirtspflanzen einige Unterschiede in der Zusammensetzung verschiedener Lebenszyklus‐Formen festgestellt werden.
Aphids of the genus Stomaphis, which have a very long stylet, are parasitic on tree trunks and feed on phloem through thick xylem. Stomaphis japonica on Quercus acutissima, Q. serrata and Q. variabilis; S. yanonis on Celtis sinensis and Zelkova serrata; and S. malloti on Mallotus japonicus were surveyed every season from 1981 to 1998 at six sites situated in natural forests in Kyoto, Japan. From fragmentary observations, their life cycles were inferred and possible host alternation of S. japonica is discussed. Stomaphis yanonis and S. malloti are monoecious and holocyclic in Kyoto, as has also been observed near Tokyo and at Ise city, Mie Prefecture, respectively. Stomaphis japonica was found throughout the year on Q. serrata passing through a holocycle, but was found only from late May to mid-November on Q. acutissima and Q. variabilis, where neither oviparae nor males occurred. Alatae flew to Q. acutissima and Q. variabilis in late May to mid-June and settled there. However, all virginoparae emerged as alatae from October and left these trees in mid-October to early November. These observations suggest that Stomaphis japonica in this area comprise two sympatric populations: a monoecious population living on Q. serrata all year round and a heteroecious population alternating between Q. serrata as a primary host and Q. acutissima and Q. variabilis as secondary hosts.
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