Establishment and Phenology of the Parasitoid Microctonus hyperodae (Hymenoptera: Braconidae) in New Zealand

Multitrophic interaction between the ryegrassLolium perenne,its endophyteNeotyphodium lolii,the weevil pestListronotus bonariensis,and its parasitoidMicroctonus hyperodae

“…In the first and second experiments the ground densities in the nil endophyte treatments were 16 m~2 (n = 2) and 14 ± 6 m~2 (n = 8), respectively. These densities were far lower than the 131 nr 2 to 436 nr 2 recorded by Goldson et al (1998) in a nil endophyte Lolium multiflorumx perenne cv. Manawa release paddock during their 1990-96 study on the same farm.…”

“…3). Goldson et al (1998) have shown that the activity of the second summer generation of adult parasitoids peaked in nil endophyte pasture in early March and tailed off towards the end of the month. Consequently, should development have been retarded in the high peramine plots, it may be argued that fewer larvae would have exited from the population as prepupae by the time of sampling in this study.…”

“…On both occasions additional weevils were also collected from all plots using a vacuum leafcollection machine (Homelite® 180V) adapted to collect litter in a net fitted to its inlet nozzle. Using a combination of weevils from both the quadrat and Homelite® collections, samples of 30-50 weevils were dissected to determine parasitism levels as described by Goldson et al (1998).…”

“…Listronotus bonariensis is one of New Zealand's most severe pests of Gramineae and, because of this, its biology and ecology are now reasonably well understood (e.g., Pottinger 1961;Goldson 1981;Barker et al 1989;Goldson et al 1998;McNeill et al 1998). The mining habit of the weevil's larval stages kills both vegetative and flowering tillers (Pottinger 1961), while the adults chew off emerging cotyledons in newly-sown stands (Goldson & Penman 1979).…”

Biology of Microctonus sp. (Hymenoptera: Braconidae), a parasitoid of Cyrtomon luridus BOH. (Coleoptera: Ccurculionidae)

“…The lack of oviposition by the parasitoid during the winter (overwintering diapause) resulted in minimal parasitism in August and September. In addition, Goldson et al (1998) observed in New Zealand three generations per year of Microctonus hyperodae (Loan), which were produced in Listronotus bonariensis (Kuschel) after diapause in September. In this case, the maximum parasitism rate reached 90% in March, decreasing rapidly in April, with the appearance of new adults from neighboring fields free of parasitoids.…”