Evaluation of Various Parts of the Paw Paw Tree, Asimina Triloba (Annonaceae), as Commercial Sources of the Pesticidal Annonaceous Acetogenins

Abstract

Various plant parts of the paw paw tree (Asimina trilaba Dunal, Annonaceae) were extracted and partitioned to concentrate the mixture of acetogenins into a standardized pesticidal extract (F005). A bioassay with brine shrimp larvae (Artemia salina Leach) was used to determine the relative potencies of the various extracts. The small twigs (0-0.5 em diameter) yielded the most potent extract (LC₅₀ = 0.04 ppm); the stem wood (LC₅₀ = 4.9 ppm) and leaves (LC₅₀ = 53.7 ppm) yielded the poorest activities. The unripe fruits, seeds, root wood, root bark, and stem bark were notably potent and, generally, yielded >2% of their dry weight as F005. The smaller diameter stems were more potent than the larger stems. We conclude that, by pollarding the trees, the entire twigs and small branches of paw paw could be processed to produce a potent acetogenin mixture; this biomass could be made available in quantities needed for commercialization of the pesticidal product and could be renewable through regrowth from the parent trunk and larger branches.