The Lesser of Two Weevils
There’s a surprising number of weevils in New Zealand horticulture news at the moment.
First we have the pea weevil, a small insect pest with a lifecycle entirely dependent on the pea, which has just been added to MPI’s radar as an invasive threat after recently being discovered in the Wairarapa. It is considered highly undesirable and, if not eradicated, could cause massive economic damage to New Zealand’s export pea seed market and the processed green pea industry.
Although there is only one generation per year, a heavy infestation can utterly devastate a crop. The Ministry for Primary Industries has recently released a factsheet detailing how to test seed for pea weevil infestations, available here.
But weevils aren’t all bad news, and some can do us a real favour. The Environmental Protection Agency has just approved the horsetail weevil as a biological control for the field horsetail weed.
Found in Whanganui, Rangitikei, Taranaki, parts of Greater Wellington and the west coast of the South Island, as well as the east coast in Havelock North, Marlborough, Canterbury and Otago, field horsetail is an invasive species that poisons livestock, endangers many of our native plants, and by extension threatens the horticulture industry.
The horsetail weevil is definitely the lesser of two evils, as is the case with many biological controls for invasive species. Horticulture New Zealand strongly supports the use of biological controls for invasive species, especially in areas where long term pesticide or herbicide control is nonviable.
- Mike Chapman, CEO