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Purple Loosestrife Biological Control Insects All four of the insect species introduced for purple loosestrife biocontrol are beetles. Beetles are hard-bodied insects with tough exoskeletons. Adult beetles possess two pairs of wings: the front pair is thickened to form a hard covering, called the elytra, which meet in a straight line down the middle of the back and cover the larger, membranous hind wings, which are used for flight. Beetles that feed on plants, like those used for purple loosestrife biocontrol, have chewing mouth parts. The four species used for purple loosestrife biocontrol belong to three different families of beetles: one family of leaf beetles (two species) and two families of weevils (one species each). Leaf beetles are small, foliage-feeding beetles; both adult leaf beetles and their larvae feed externally on plant foliage. Larval feeding often is more damaging, and can result in complete defoliation of plants. Weevils are generally plant-feeding beetles with long snouts bearing chewing mouthparts at the tip. They use the snout to chew and feed inside plant tissues or to notch out holes in which to lay their eggs. Similar to leaf beetles, weevil larvae (which feed internally in the stems, roots or flowers) often cause more damage to plants than adults. However, some weevil adults do cause significant feeding damage to foliage. The leaf beetles are Galerucella calmariensis L. and Galerucella pusilla Duftschmidt; one weevil is a root-mining weevil, Hylobius transversovittatus Goeze and the other is a flower-feeding weevil, Nanophyes marmoratus Goeze (Table 3). Each species is described in the following sections.
Table 3. Purple loosestrife biological control insects. (Top and center: UGA1291044 and UGA1291045) |
Invasive and Exotic Species |
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