<i>Paropsis charybdis</i> defoliation of <i>Eucalyptus</i> stands in New Zealands central North Island

Abstract

Paropsis charybdis, the most serious pest of Eucalyptus in New Zealand, was controlled with the introduced Australian egg parasitoid Enoggera nassaui in the late 1980s. Using frass traps to monitor P. charybdis populations, we report that pest outbreaks still occur, resulting in heavy defoliation of susceptible Eucalyptus species. The results suggest that the presence of large larval populations and commensurate defoliation result from poor spring parasitism by the parasitoid. A second wave of P. charybdis oviposition is effectively attacked, preventing late season defoliation by larvae. A climatic mismatch of E. nassaui is suspected to be the cause of this poor performance.

Detection of a Tasmanian strain of the biological control agent <i>Enoggera nassaui</i> Girault (Hymenoptera Pteromalidae) using mitochondrial COI

“…The solitary egg parasitoid Enoggera nassaui Girault was obtained from Western Australia (= Perth strain) and released as a classical biological control agent in 1987 (Kay 1990). Bain & Kay (1989) were concerned that this population may not be climatically tolerant of inland New Zealand conditions, a theory supported by Murphy & Kay (2000), who found that low parasitism rates during spring were associated with high levels of P. charybdis defoliation in the central North Island region.…”

The seasonal abundance of the newly established parasitoid complex of the Eucalyptus tortoise beetle (<i>Paropsis charybdis</i>)

“…A second peak in eggs occurs in February following the emergence of second generation adults (Stevens 1973;Kay 1990;Murphy 1998). Murphy & Kay (2000) also found this same trend when they monitored P. charybdis populations from 1997-1998 using frass collection.…”

“…This was thought to be due to high overwintering mortality of E. nassaui. By March however, good control of the P. charybdis population was generally achieved with at least 80% egg parasitism (Murphy & Kay 2000). Although there is only one season of data with which to compare the present complex of parasitoids to the earlier situation, some significant changes are evident.…”

Incidence of and defoliation by a newly introduced pest, <i>Paropsisterna variicollis</i> (Coleoptera: Chrysomelidae), on eleven durable <i>Eucalyptus</i> species in Hawke’s Bay, New Zealand

“…This indicates the sampling period of 18 to 26 January used here may not have been well timed to capture these important early developmental stages. Both Murphy and Kay (2000) and Jones & Withers (2003) noted January as being between the first (spring) and second (summer) generations of P. charybdis and this may have also been the case for Pst. variicollis.…”

“…Amongst these is a suite of drought-and frost-tolerant eucalypts being assessed by the New Zealand Dryland Forests Initiative (NZDFI) to develop a naturally ground-durable eucalypt timber resource in dryland regions of New Zealand (Apiolaza et al 2011;Millen 2009), including the Hawke's Bay. Two other well-established Australian paropsines, Paropsis charybdis and Trachymela sloanei, already Refer to http://www.nzpps.org/terms_of_use.php cause significant defoliation in some New Zealand eucalypt plantations (Walsh 1998;Murphy & Kay 2000), and T. sloanei is a pest in California (Paine et al 2000). Like these species, Pst.…”