The rust Puccinia menthae on lesser calamint

Chrysolina suffriani on lesser calamint

Pupa of the gall midge Asphondylia nepetae in flower of lesser calamint

Lesser calamint

Damage of stem mining Lepidoptera lava on lesser calamint

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Project Overview

So, what’s the problem

Lesser calamint (Calamintha nepeta) is an aromatic perennial herb in the mint family, Lamiaceae. Originating from Europe, it has been introduced to New Zealand where it is a weed on the east coast of the North Island. It is not palatable to livestock and it is displacing desirable pasture species. Although not yet widespread, lesser calamint is already having negative economic impacts on infested properties.

Controlling lesser calamint is difficult. Due to its rhizomatous root system and small hairy leaf area, using chemicals is not feasible, and mechanical control is impractical. However, biological control, i.e. introducing natural enemies from the weed’s area of origin, could be a valid option.

One reason for the plant’s impact may be the absence of natural enemies that attack it in its area of origin. The challenge is to find natural enemies that attack lesser calamint but do not damage related popular herb or native species.

What is this project doing?

A preliminary literature survey revealed several herbivores and fungal pathogens that may have potential as biological control agents for lesser calamint.

In 2018, CABI was asked by Landcare Research, New Zealand to conduct surveys for potential agents in the native range of lesser calamint in Europe, and to collect plant material for DNA analysis to help determine this species’ area of origin in New Zealand.