Submitted to: Pest Management Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/8/2002
Publication Date: 10/21/2002
Citation: MEEPAGALA, K.M., STURTZ, G., WISE, D., WEDGE, D.E. MOLLUSCICIDAL AND ANTIFUNGAL ACTIVITY OF ERIGERON SPECIOSUS STEAM DISTILLATE. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2002. v. 58. p. 1043-1047. Interpretive Summary: The ram's horn snail is an intermediate host for a parasitic trematode that has recently been discovered to be a significant problem in commercial channel catfish production ponds in the Mississippi Delta region. The life cycle of this parasitic trematode is believed to involve the ram's horn snail, channel catfish, and the white American pelican. The first intermediate host, the ram's horn snail, is infected by miracidia hatched from the eggs of an adult trematode. After the development of the miracidia into larval cercariae, the larvae of cercariae are released from the snail and then infest channel catfish through the skin, where they develop into metacercariae. Fish infested by the metacercariae subsequently develop cysts, experience impaired growth, and are prone to other secondary infections. The life cycle is completed when the infested fish is consumed by the final host, the white pelican, and metacercariae complete their development into adult trematodes. These adult trematodes lay eggs in the intestine of the bird and are then released with the bird feces into the pond, and thus the life cycle is repeated. One approach to disease control is to avoid infestation of catfish by breaking the life cycle of the parasitic trematodes through eradication of the ram's horn snail. In our search for natural product-based agrochemicals, we found that the steam- distilled oil of Erigeron speciosus is lethal for ram's horn snails and fungicidal against important plant pathogens that cause anthracnose diseases of strawberry.
Technical Abstract: The steam-distilled fraction of the aerial parts of Erigeron speciosus was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea, Colletotrichum acutatum, C. fragariae, C. gloeosporioides, and the intermediate host snails Planobdella trivolvis that harbor the trematodes (Bolbophorus confuses) that infest and cause severe infections in pond-raised catfish in the Mississippi Delta region of the USA. Bioautography on silica TLC plates demonstrated the presence of antifungal activity of the steam distillate. Preliminary bioassays of the steam distillate indicated the presence of phytochemicals with lethal toxicity to P. trivolvis. The bioactive compounds 2Z, 8Z-matricaria methyl ester and its 2E, 8E-geometrical isomer were isolated by bioassay-guided fractionation and chromatographic techniques and identified by 1H NMR spectroscopy.