The Seasonal Abundance and Feeding Damage of Hypsipyla grandella (Lepidoptera: Pyralidae) in Seed Capsules of Swietenia Mahagoni in Florida

Abstract

Larvae of Hypsipyla grandella attacked the seed capsules of West Indies mahoganies, Swietenia mahagoni Jacquin, in spring (March - April) after the capsules dehisced and the seeds were exposed, which occurred prior to flushing. One to 5 larvae occurred per capsule. The seeds apparently were a preferred food source and 50-96% of the seeds in capsules examined in June were damaged by larvae. Seed capsules during their period of expansion from early summer to winter were virtually free of borer attack, and during this period neither hardened-off shoots nor persistent capsule cores from previous seasons served as food sources for more than a few larvae. The hardness of the capsule valves is apparently a factor in preventing penetration by the larvae. Although the persistence of seeds in the capsules is transitory, and the availability of capsules more limited and more variable than that of shoots, the seed capsule contents appeared to be preferred as a food source, as higher percentages of dehisced seed capsules than new shoots were attacked when both were simultaneously available. The damage by H. grandella to mahogany seeds impacts regeneration of this tree species.