Purple loosestrife, Lythrum salicaria L., an exotic, wetland perennial, forms large, monotypic stands throughout many temperate regions of the U.S. and Canada. This invasive plant replaces native vegetation, degrades wildlife habitats, and obstructs waterways. A two-year research project was initiated in 2000 to assess the impact of a North American flea beetle, Altica litigata, on leaf consumption and seed production of purple loosestrife in eastern Tennessee.
The sampling site was monitored two to three times weekly from mid April to early September. To assess impact of adult feeding on numbers of seed capsules and seeds/capsule, plants were placed into four damage rating categories: 1) none, 2) minor, 3) moderate, and 4) major. Ten additional plants, heavily damaged by larvae, also were evaluated. Plant height, number of seed capsules/lateral, number of laterals, and number of seeds/capsule were measured. In the laboratory, leaf consumption by adults was measured using a leaf area meter. Adults (0, 2, 4, or 6 male or female) were fed foliage, which was measured and replaced every 2 days.
Both adults and larvae feed on foliage. Larval feeding was extensive; skeletonized foliage appeared "burned" and reduced plant viability and flower maturity. Larval damage caused large reductions in seed production and seeds/capsule. Leaf consumption by adults will be presented and discussed.
A large population of a native, herbivorous insect, A. litigata, was found feeding on purple loosestrife; damage, especially by larvae, greatly impacted production of seed capsules and seeds. This incidence of A. litigata may represent a new state record. Further research is underway to better understand the biology, impact, and biological control potential of A. litigata on purple loosestrife.
Species 1: Coleoptera Chrysomelidae Altica litigata
Keywords: biological control, invasive species
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