The potential impact of climate change on 'Nezara viridula' (L.) (Hemiptera: Pentatomidae) and its parasitoid, 'Trichopoda giacomelii' Blanchard (Diptera: Tachinidae) in Cambodia and Australia: Ecological, behavioural and physiological assessments

Abstract

'Nezara viridula' (L.) (Hemiptera: Pentatomidae) is a cosmopolitan, polyphagous heteropteran insect that causes economic damage to many crop species worldwide. Despite several interventions attempts, 'N. viridula' has remained a significant pest in certain regions of Cambodia and eastern Australia, particularly those where soybean and nut crops are cultivated. Recently, 'Trichopoda giacomelii' Blanchard (Diptera: Tachinidae), a species native to Argentina was established in Australia as an effective biological control agent for 'N. viridula' in one instance. However, with predicted climate change, the range of the pest could expand or change and the relationship between the pest and the parasitoid could also change in response to altered temperature and precipitation regimes. Changed climatic conditions could affect the pest status and geographic range of 'N. viridula' as well as the efficacy of the parasitoid. Climate change will potentially affect the interactions between factors such as temperature, humidity, light, food, and the wellbeing of the pest and the parasitoid and the relationship between the two. The aims of this study were (i) to evaluate the sampling methods of arthropods on soybean crops in Cambodia, in terms of accuracy of the use of the two main sampling methods: sweep netting and beat sheeting; (ii) to measure the effect of changed temperature and moisture regimes on 'N. viridula' and 'T. giacomelii' life cycles in populations from contrasting climatic regimes (Breeza and Grafton); (iii) to measure the effect of changed temperature and moisture regimes on the ability of the parasitoids to parasitize 'N. viridula'; and (iv) to investigate the various physiological variables of 'N. viridula' under the stress of temperature.