New Zealand porina moth

Wiseana despecta is a moth species belonging to the family Hepialidae. Often referred to as a porina moth, it is a major pasture pest native to New Zealand. The economic impact of this species is primarily linked to the severe damage its larvae inflict on grasslands and various forage crops.

The pest primarily targets pasture grasses, such as ryegrass and clover, but it also causes significant damage to cereal crops and various vegetable plantings. The larvae are subterranean, feeding on the roots and crown of the plants, which severely compromises the crop's ability to regenerate and survive under stress.

Regarding its biology, the insect completes one generation per year. Female moths lay eggs directly onto the pasture surface. Once hatched, the larvae construct deep, vertical tunnels in the soil. They stay in these burrows during the day to avoid predators and desiccation, emerging at night to forage on the surrounding vegetation.

The damage is characterized by bare patches appearing in paddocks and stunted growth of plants. In high-density populations, the larvae can strip the surface area bare, leading to significant soil erosion and loss of livestock feed. The damage is most visible during late autumn and winter when the larvae are actively growing.

Management strategies for Wiseana despecta involve a combination of monitoring and integrated pest management (IPM). Farmers often utilize intensive grazing to expose larvae to birds and sunlight. Biological control options include applying Beauveria bassiana or specific nucleopolyhedroviruses (NPVs) which can drastically reduce larval populations without chemical residues.