Wiseana Research Articles

Growth rate survival and preference of porina (<i>Wiseana</i> spp) to selected grasses

Porina (Wiseana spp) has become a major pasture pest in New Zealand over the past century in response to natural forest and grasslands being converted into pastures for livestock Limited information is available on the growth and survival of porina larvae on native host species Field collected porina larvae were fed on 5 selected native plants (Festuca actae Aciphylla squarrosa Poa cita Chionochloa rubra and Phormium tenax) one exotic (Lolium multiflorum cv Manawa) and mixed species over 5 months and the fitness response of porina to each of these grasses was measured The most rapid growth of larvae was observed on L multiflorum while the slowest was on P tenax A squarrosa and P cita The largest weight gain was on L multiflorum There was a significant difference in larval growth between L multiflorum and P tenax (P0019) Percentage mortality was lowest on L multiflorum (125) with the larvae surviving for 177 days The highest mortality of 75 was recorded on P cita which also had the lowest survival of 77 days This study provided useful information on the development of porina on native hosts which provide a habitat for its expansion on to pasture

Potential for biological control of porina (<i>Wiseana</i> spp) with a novel insecticidal bacterium <i>Yersinia</i> n sp (MH96) EN65 strain

Porina (Wiseana spp larvae) are endemic pests of pasture If detected early young larvae can be controlled with diflubenzuron but generally damage is not predicted and organophosphate insecticides (eg diazinon chlorpyrifos chlorfon) are required Yersinia n sp (MH96) cf entomophaga (EN65 strain) a novel bacterium with insecticidal properties is pathogenic to late instar Wiseana spp larvae in laboratory assays and has potential as a biopesticide This trial measured the effect of two formulations of EN65 and a commercial formulation of Bacillus thuringiensis var kurstaki (Btk) against late instar porina EN65 was formulated in a sprayable biopolymer and on to a kibbled wheat bait Both EN65 formulations caused significant mortality of porina larvae and reduced feeding damage on white clover; efficacy was superior to Btk Survival of the bacterium in the sprayable biopolymer formulation was enhanced compared to a nonformulated broth culture Bacterial survival on the kibbled wheat bait was better when stored at 4C compared to 20C over 3 months

Susceptibility of <i>Wiseana</i> species to diflubenzuron and implications for field applications

Porina control using diflubenzuron is popular due to its low cost and benign environmental effects The level of control in Otago and Southland however can be variable and may be associated with species diversity in the region In this investigation larvae of Wiseana cervinata W copularis W jocosa and W mimica were exposed to diflubenzuron in two laboratory bioassays All species were killed with small larvae killed more quickly than large There were only minor differences in susceptibility between species Adult flights at three sites showed variation in the main flight period suggesting that larvae in pasture in autumn would cover a wide size range This was confirmed by field sampling The timing and frequency of diflubenzuron applications should be considered in conjunction with the phenology of adult flight and subsequent larval development and climatic conditions affecting larval survival

Departmental results for control of Wiseana spp

Departmental results for control of <i>Wiseana</i> spp