Factors influencing the honeydew production of Ultracoelostoma scale insects in New Zealand beech forests

Type of content
Theses / Dissertations
Publisher's DOI/URI
Thesis discipline
Ecology
Degree name
Master of Science
Publisher
University of Canterbury. Biological Sciences
Journal Title
Journal ISSN
Volume Title
Language
Date
2013
Authors
McBride, James Alexander
Abstract

In New Zealand Nothofagus forests Ultracoelostoma spp. scale insects produce abundant honeydew which is an important food for native birds, invertebrates, sooty mould, and invasive wasps. Previous models have underestimated honeydew production, potentially because they do not allow for the flow rate of honeydew to vary between insects based on characteristics such as insect size. This research focused on honeydew production rates at the level of the individual insect, how insect characteristics influence production, and whether the strongest predictor of production, ambient air temperature, acts directly on insects or indirectly via effects on trees. Finding out how temperature acts to increase honeydew production will better reveal the physiological processes involved. The study site was Mt. Richardson, Canterbury.

In the first part of this study, during March-April 2012, daily mean ambient temperature (range 7.2 – 15.1 °C) had a positive relationship with honeydew production. Insect size positively influenced production at high temperatures, with the largest insects producing 0.296 µg insect⁻¹ h⁻¹ and the smallest insects 0.115 µg insect⁻¹ h⁻¹ at the highest temperature, 15.1 °C.

In the second part of this study, during October 2012-January 2013, I manipulated temperature on areas of tree trunk using reflective or clear plastic covers, creating a mean temperature difference of 1.1 °C. However, the effects of tree and insect temperature could not be separated as there was no relationship between either manipulated or ambient temperature and honeydew production.

These results show that honeydew production is influenced by individual insect characteristics. This will be important for future models of production. The results also show contradictory effects of temperature on honeydew production, perhaps because of interactions with other unknown factors, which bears further investigation.

Description
Citation
Keywords
Honeydew, Scale insect, Ultracoelostoma, Nothofagus, Beech forest
Ngā upoko tukutuku/Māori subject headings
ANZSRC fields of research
Rights
Copyright James Alexander McBride