Recently the War Memorial Centre hosted the annual New Zealand Entomological Society conference, and researchers from all over the country congregated to share their discoveries and find out what was happening in the world of bugs.
One of the talks was very relevant to Whanganui residents. In January, a Springvale couple discovered an odd-looking bee when it stung one of them. Realising it was unusual they forwarded the corpse to the Ministry for Primary Industries. James Haw of MPI explained it was identified as a species of Australian resin bee, Megachile ustulata, never before recorded in New Zealand. MPI searched the neighbourhood for more bees but came up empty-handed. In Australia Megachile ustulata is a solitary insect that makes its home in cracks and burrows. It especially likes the hollow ends of bamboo garden stakes. It is not clear if this was a one-off incursion, or if these bees have taken up residence in Whanganui. If you’re a keen amateur naturalist, keep your eyes open for resin bees when spring arrives. Feel free to bring possible specimens to the Museum (in sealed containers, please).
One of the more intriguing talks was by Adele Parli, a Masters student at the University of Otago, working on Wellington tree wētā (Hemideina crassidens). The Wellington species is the more aggressive of the two tree wētā we get in the Whanganui area. Adele was quantifying their aggressiveness with a measure known as the “poke test”; how many times do you need to poke the wētā before it flips its lid and begins to thrash and bite? The answer for the Wellington tree wētā was generally “once”. Adele was poking wētā to test whether their behaviour changes after feeding on the poison brodifacoum. Brodificoum is commonly used for rat and mouse control in the bush and around buildings, and is the rat poison anyone can buy at the supermarket without a permit. (It’s much less humane than 1080 and takes longer to break down in the environment, but you don’t see people protesting brodifacoum outside supermarkets.) Wētā love to eat brodifacoum bait pellets, and it doesn’t kill them, but Adele suspects it may be changing their behaviour, such as how often they emerge to feed, how far they travel, and how aggressive they are.
As well as talks on insects, there were presentations on spiders, which are more or less an honorary insect at these events. Anne Wignall at Massey University Albany had been studying a common house spider, the daddy-long-legs Pholcus phalangoides. These are territorial, staking out one corner of a ceiling and repelling intruders. Anne was curious about whether these spiders could recognize each other; something called the “dear enemy” effect in vertebrates, where animals are more aggressive to complete strangers than rivals they’ve already encountered. Sure enough, when spiders were allowed to become familiar with each other, their territorial battles, while no less frequent, became less violent. It’s remarkable to think that a creature with such a tiny brain can remember its opponents and assess the risk of fighting.
The conference finished with Bugs in the Pub in Frank eatery. Three entomologists gave short talks on beetles, insect weaponry, and whether we should eat more bugs, and invited questions from the audience. Afterwards, beers in hand, pubgoers chatted with the scientists and looked at a selection of live insects they’d brought along – a fitting end to a grand three-day conversation on the wonders of the insect world.
Dr Mike Dickison is Curator of Natural History at the Whanganui Regional Museum.