Conference Agenda

The Australasian harrier Circus approximans is native to Australia, New Zealand and the South Pacific. Although an opportunistic predator, much of its diet consists of carrion, mainly roadkill. Besides a record of a single, unnamed capillariid nematode there have been no investigations into the parasites of harriers in New Zealand, and there are no parasite records for them elsewhere in their range. A helminthological survey of 65 deceased harriers from southern New Zealand uncovered a helminth fauna comprising six species. Porrocaecum circinum (Nematoda) was previously described only from poor material from Australia. Procyrnea fraseri (Nematoda) is new to science, and includes specimens previously reported from Australia under an erroneous name. Strigea falconis, a widespread trematode, is reported for the first time in New Zealand. Cladotaenia anomala (Cestoda), a species with unusual scolex spine distribution, and Polymorphus circi (Acanthocephala) were found to be new species, and both were the first of their genus from New Zealand. An unnamed species of capillariid is mainly confined to North Island and is rare in South Island. Phylogenies are presented for each species based on DNA sequence. Potential intermediate hosts are discussed, and the origins of the helminths and their potential for pathogenicity are considered.

Many parasites have the adaptive ability to modify the phenotype of their host to complete their life cycle, a trait known as host manipulation. Here, we expect to see differences in the responses of infected animals toward certain cues, especially if a cue ultimately favours parasite transmission. In freshwater hairworms (Nematomorpha: Gordiida), mature individuals somehow “drive” their terrestrial insect hosts into water, where the hairworm exits to mate. Infected insects appear more active at night and respond to environmental cues differently than uninfected ones, however, we do not know how these differences evolve throughout hairworm development. Using Acheta domesticus crickets experimentally infected with Paragordius varius hairworms in a time series of behavioural assays, we tested multiple stimuli to determine how hairworms modulate host behaviour, and whether these behaviours correlate with hairworm development. Humidity, horizontally polarised light, and direct contact with water were tested in isolated behavioural assays. We noticed a remarkable behaviour reminiscent of apple bobbing in the water assay. Also, hairworms apparently needed to contact water to egress, otherwise they would retreat back into the host. We discuss these behaviours along with the responses of infected crickets to humidity and light, and link these to the broader sensory landscape.

Alterations to natural landscapes by human activities can change patterns of parasite transmission. The type of landscape alteration and life histories of parasites and their hosts, influence parasite burden. To investigate whether parasite burden is associated with land use change, we conducted a country-wide survey of bat and rodent parasites across Cambodia. Our results show that, agricultural land use types and areas with a mosaic of different land cover types exhibit a greater parasite burden compared to other landscapes, such as forested areas. Bats showed a lower parasite burden in fragmented habitats and urban areas, whereas fragmentation had no discernible impact on parasite burden in rodents. However, rodents had a higher parasite burden in urban areas when compared to other land use types. In cities, lower parasite burden in bats may reflect changes in resource acquisition that remove parasites from their food webs. Conversely, urban rodents have higher parasite loads, likely from higher density and improved body condition enabled by human food subsidies. This dichotomy highlights the nuanced effects human-modified landscapes can have on host-parasite associations, offering insights into disease ecology in rapidly changing ecosystems.