Ecology of Thaumastocoris peregrinus, a recently arrived Eucalyptus pest in New Zealand

Abstract

Thaumastocoris peregrinus Carpintero and Dellapé (Hemiptera: Thaumastocoridae) is a sap-feeding insect native to Australia and is a serious pest of Eucalyptus species. This pest has been detected in several countries worldwide and has recently invaded Auckland, New Zealand. This invasive insect can heavily impact eucalypt plantations and cause not only economic losses to the forestry industry but also negatively affect society by damaging urban trees in public spaces such as streets and parks. In order to undertake any pest control program, it is essential to understand the ecology and biology of the target species. This information will help inform decision making in order to minimise the impacts of the pest on the forestry industry. This research aims to: 1) determine the thermal tolerance of T. peregrinus at different temperatures 2) evaluate the suitability of four Eucalyptus host species for the development of T. peregrinus and 3) develop a climate model to predict the potential distribution of T. peregrinus in New Zealand and worldwide. The first goal was achieved by rearing a colony of T. peregrinus under laboratory conditions at three different constant temperatures and evaluating development during its complete life cycle. The second goal was approached with a laboratory experiment rearing T. peregrinus on Eucalyptus foliage of four different species, where three of them are economically important for the forestry industry and the other is a popular amenity tree. Using the climate modelling software, CLIMEX™ version 3.0, the potential geographic distribution of T. peregrinus was predicted. The thermal tolerance experiments allowed us to identify the thermal limits for T. peregrinus development being a lower temperature threshold of 4ºC and an upper temperature threshold of 35ºC. Additionally, development of eggs, nymphs and adults was evaluated and fecundity parameters were also calculated. In the second experiment, E. nitens was identified to be a viable host of T. peregrinus. On the other hand, the insect did not survive on Monocalyptus species E. fastigata and E. regnans. According to the predicted climate modelling, T. peregrinus has the potential to expand its current distribution westwards into Mediterranean and semi-arid climates and also northwards into tropical and subtropical zones around the world. This thesis contributes to the knowledge of the biology and ecology of T peregrinus. The three objectives mentioned above all provided valuable information that can be applied to develop risk minimisation strategies for the forest industry as well as assist with future T. peregrinus management and control programs. This will result in economic benefits to New Zealand by reducing the substantial costs associated with the negative effects that this pest may cause to eucalypt plantations and amenity trees.