About 110 introduced aphid species (Hemiptera: Aphididae) have been recorded in New Zealand. Only 12 indigenous species have been recorded. per year over the last 130 years although this rate has declined dramatically in recent years. The origins of introduced aphids appear to include most parts of the globe. Many introduced aphids damage economically important plants through their feeding and transmitting plant viruses. Less quantifiable environmental impacts include injury to native plants and the displacement of native aphids on their host plants. Aspects of aphid biology, such as small size, parthenogenetic reproduction, high reproductive rates, short generation time, rapid dispersal and eruptive population dynamics, pose particularly difficult challenges for aphid biosecurity in New Zealand.
Aphid vectors of barley yellow dwarf virus (BYDV) were sampled from three 7.5 m high suction traps in Canterbury from April to October 1998. Aphid numbers were very high (up to 193 aphids per trap per week) in April and May and medium to low (0 to 44 aphids per trap per week) from June to September. A BYDV forecast based solely on numbers of aphids caught in traps (aphid flights), or primary infestation, accurately predicted high virus incidence for wheat sown before mid-May. However, an exceptionally mild winter encouraging the secondary spread of aphids within crops was implicated in the high level of BYDV found in wheat crops sown after mid-May that was not predicted by aphid flights. A measure of secondary aphid infestation and virus infection may need to be included in future BYDV forecasts.
The lettuce aphid (Nasonovia ribisnigri) was first reported in New Zealand on lettuce (Lactuca sativa) in Canterbury in March 2002. During autumn 2002, the lettuce aphid was collected in three suction traps (7.5 m high) around Canterbury. Within one year it had spread to all of the main lettuce growing regions of the country, mostly as a result of transporting aphidinfested fresh lettuce or lettuce seedling transplants to these regions. It was found on its primary host, Ribes spp. (e.g. currants and gooseberries), and moved to its secondary hosts (e.g. lettuce and weeds) in late spring, having survived the winter in sexual and asexual forms. Up to 73 lettuce aphids per flower head were found on flower buds and flowers of some widely distributed weeds in New Zealand, including Crepis spp., Hieracium spp., Cichorium intybus and Lactuca virosa, during summer and autumn 2003. This infestation resulted in a number of crops being deemed unfit for marketing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.