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What is it? Lacanobia subjuncta (Grote & Robinson) (Lepidoptera: Noctuidae) occurs throughout North America and feeds on a wide range of plants, including several crops. In recent years larvae of this insect have become more common in commercial orchards and have caused considerable fruit injury. Because this insect is relatively new as a problem in orchards, much still need to be defined in terms of its biology and phenology. There are two generations of L. subjuncta in WA. It overwinters as a pupa in the soil and damage adults emerge in May and June. Larvae are present in June feeding on foliage when young and on fruit and foliage when older. Larvae will remain in the tree unlike other cutworms, which return to the ground and only feed in trees at night. When larvae are young they are light green with a white stripe along the side. As larvae grow they transform into a light brown color with darker markings on the upper surface. Larvae are voracious feeders and can defoliate shoots in a few days. A second generation occurs in July and August with larvae feeding on foliage and fruit in August and September. Dr. Peter Landolt, USDA-ARS in Wapato, has identified a pheromone for Lacanobia subjuncta. This pheromone has been used to monitor seasonal activity of the adult moths, but is so attractive that it is not yet useful for determining population densities within orchards. Growers and crop consultants must use visual examination of shoots for feeding or beating trays to dislodge larvae in order to determine the need to apply controls. In preliminary chemical control tests conducted in 1998, Lorsban and Lannate provided the best control of Lacanobia subjuncta. Growers have also reported Thiodan as being effective. Lannate can result in suppression of predatory mites and disruption of integrated mite management so caution should be exercised when using this product. Additional insecticide screening tests are underway and will be reported when completed.
Phenology and reproductive status In Washington, adults of Lacanobia were collected using three trap methods: blacklight traps, female sex pheromone-baited traps, and traps baited with synthesized food bait attractant. Traps were checked twice per week for lacanobia moths. Female moths were retained in ETOH and later dissected to determine the number of times mated and the reproductive status. First generation adult males were attracted to pheromone traps beginning on April 30th. First generation females were collected on May 17th. Seasonal flight period was shorter for female than male in the first generation. Lacanobia fruitworm larvae were sampled from apple foliage using beating sheet and pole, the larvae were counted and head capsule measurements taken. First generation neonate larvae appeared on June 16th. |