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Bacterial canker of kiwifruit commonly referred to as Psa is caused by Pseudomonas syringae pv actinidiae and the biovar 3 strain has affected kiwifruit vines in New Zealand since 2010 Psa has had an impact on the management and production of kiwifruit in New Zealand This paper provides a review of the epidemiological risk factors that are associated with Psa disease within orchards The presence of the pathogen rain and a susceptible host are sufficient to cause disease in kiwifruit but there are other risk factors that can increase the amount of disease that develops and the spread of disease including other environmental factors (eg temperature) host factors (eg cultivar) and management factors (eg pruning practices) The aim of this literature review was to describe the current knowledge of a range of known and postulated risk factors for the development of bacterial canker in kiwifruit

Summary A laboratory study of isolines of Pseudococcus calceolariae (Maskell) and P. similans (Lidgett) collected from Hawke's Bay and Auckland, two widely separated regions in the North Island of New Zealand, threw doubt on the validity of the defining characters of these species. For P. similans, the number and position of oral rim tubular ducts varied widely and sometimes fell outside the defined limits for the species, and characteristic ‘stout abdominal setae’ were lost in the F1 generation. The morphological characters that separate one species from the other were manipulated by changing the temperature at which the mealybugs developed, such that cohorts of F1 sisters reared in the laboratory contained phenotypes of both P. calceolariae and P. similans. No impediments were found to breeding among populations of P. calceolariae and P. similans from Hawke's Bay and Auckland. All combinations of crosses between virgin females and males produced viable progeny. Those reared at 16°C laid more eggs than those reared at 23°C. The data did not suggest the existence of cryptic or sibling species, and contrasted with experiments elsewhere which quite clearly showed species incompatibility of closely related mealybugs. Examination of 160 ‘wild’ specimens of P. calceolariae from New Zealand, Australia and California (U.S.A.) and P. similans from New Zealand and Australia showed a morphological continuum from one species to the other. It is concluded that P. calceolariae and P. similans merely represent the phenotypic extremes of one widely polymorphic species, with the morphological characters of individual adults determined by the microenvironment in which they developed. Pseudococcus calceolariae is thus the senior synonym of P. similans.

Ctenopseustis obliquana (Walker) is one of the key pests of horticulture in New Zealand and there is interest in the provision of flowering plants within orchards to increase the effectiveness of biological control. A trial was carried out to evaluate the potential impact of providing nectar sources within orchards on the longevity and fecundity of this pest. Newly eclosed pairs of moths were set up in the laboratory and provided with a supply of either honey or water, or remained unfed. The age-specific reproduction of pairs was determined each day throughout their lives. Provision of both water and honey significantly increased longevity and numbers of eggs laid per female compared to moths that were not provided with a source of honey or water. Moths provided with honey had significantly greater longevity than moths provided water, but total egg production and number of days spent egg laying was not increased. Moths provided honey had a prolonged post-ovipositional period compared to moths only provided with water. It is concluded that the provision of nectar sources within orchards is not likely to increase the reproductive capacity of C. obliquana but the suitability of any new plants as hosts for larval C. obliquana needs to be evaluated.

Greenhouse thrips (Heliothrips haemorrhoidalis Bouché) (Thysanoptera: Thripidae) damage citrus, avocados and ornamental plants in New Zealand. A larval parasitoid, Thripobius semiluteus Boucek (Hymenoptera: Eulophidae) has been imported into quarantine from California. Preimaginal development times varied considerably between T. semiluteus and its host greenhouse thrips at 23°C, with times of 21.7 days and 37.7 days respectively. T. semiluteus adults survived an average of 2.9 days and laid an average of 20.3 eggs per female with most being laid on the second day. T. semiluteus has a lower net reproductive rate than greenhouse thrips (13.9 and 44.7 respectively) although the faster generation time of T. semiluteus results in a higher intrinsic rate of increase (0.1101 and 0.0526 respectively). These results suggest that T. semiluteus has the potential to reduce population levels of greenhouse thrips if released into New Zealand.