Lesser budworm

Lesser budworm (Heliothis punctifera) larvae have been identified for agronomist, Matt Tubb (Landmark), from a wheat crop north of Deniliquin, in the Riverina district of New South Wales. Matt says the larvae had chewed holes into the second node of some plants and were observed feeding inside the stems. This appears to have restricted the transport the water and nutrients within plants, resulting in the appearance of white heads; damage that superficially resembled crown rot. Although the caterpillars were fairly widespread across the 200 ha cereal crop, Matt reports the overall number of affected plants was relatively low and unlikely to reduce yield. Since sending in the sample for identification, Matt has returned to the affected paddock. Matt says the damage had not worsened and numbers appeared to have dropped off considerably.

Lesser budworm is closely related and similar in appearance to the native budworm (Helicoverpa punctigera), although they are only occasionally observed in agricultural areas of south-eastern Australia. Early larval instars of these two species are very difficult to tell apart. Larvae of both species have a light coloured strip down each side of the body, which can vary in colour. For older larvae (> 20 mm in length), lesser budworm have white hairs on the collar (segment behind the head) and the body, while native budworm have black hairs on the collar and black to blackish-brown body hairs. A hand lens or microscope is required to observe this difference.

Outbreaks of lesser budworm are a rare event as a unique combination of biological and climatic conditions are required. The last outbreak occurred in spring 2005 where this species caused significant damage to a broad range of crops including lupins, lentils, medics, lucerne and vetch and, to a lesser extent, field peas, faba beans, canola and cereals. In other years, we have received only a handful of reports mostly from the Central West Slopes and Plains, South West Slopes and Riverina districts of New South Wales. The lesser budworm normally occurs in outback Australia where they feed on desert daisies. Conditions that may favour outbreaks are significant inland summer rains which trigger growth bursts of vegetation, enabling moth numbers to build up, followed by favourable winds that enable long distance flights into agricultural and pastoral districts.

Click here for images of the lesser budworm.