Molluscicidal activity of vulgarone B against ram's horn snail (Planorbella trivolvis)

The ram's horn snail (Planorbella trivolvis (Say)) is an intermediate host for a digenetic trematode (Bolbophorus confusus (Krause) Dubois) that has recently been discovered to be a significant problem in commercial channel catfish (Ictalurus punctatus Raf) production ponds in the Mississippi Delta region in the USA. In these catfish ponds, the digenetic life cycle of this parasitic trematode involves two intermediate hosts, the ram's horn snail and the channel catfish, and the final host, the American white pelican (Pelecanus erythrorhynchos Gmelin). One approach to eradicate this problem is to disrupt the life cycle of the parasitic trematodes by eliminating the snails. During our search for natural-product-based molluscicides to control the snails in the catfish ponds, vulgarone B, isolated from the steam distillate of the aerial parts of the plant Artemisia douglasiana Besser (Asteraceae), was found to be active towards the snails with a LC50 of ca 24 microM. Channel catfish toxicity studies indicated a LC50 of ca 207 microM. Vulgarone B may be an environmentally acceptable alternative for snail control in aquaculture.     

中国松塔牛肝菌属,假黑伞属和黑伞属的新记录种

记述在海南岛发现的中国松塔牛肝菌属、假黑伞属和黑伞属的新记录种角鳞松塔牛肝菌(Strobilomyces foveatus Corner.)、黄褐球盖菇(Stropharia coronilla Bull.)和卷鳞灰黑菇(Agricus meleagris J.Schaeffer),以及我国未详细报道的疣鳞松塔牛肝菌(Strobilomyces nigricans Berk.)和刺疣松塔牛肝菌(S.confusus、Sing.)的形态。     

Encapsulation of Bolbophorus damnificus (Digenea: Bolbophoridae) Metacercariae in Juvenile Channel Catfish,Ictalurus punctatus,Is Linked to Delayed‐onset Mortality

Bolbophorus damnificus (Digenea: Bolbophoridae) causes significant economic losses in catfish aquaculture in the southeastern USA. To determine mortality trends associated with B. damnificus exposure, three separate disease challenges were conducted. The first challenge exposed channel catfish, Ictalurus punctatus, fingerlings (7–13 cm) to approximately 285 B. damnificus cercariae/L, while the second exposed fish to approximately 215 cercaria/L. Fish were monitored for morbidity and mortality for 28 d. In both studies, mortality first occurred 8 d postchallenge (PC) and peaked at 9 and 10 d PC, respectively. Mortality had subsided by 14 d PC, with only sporadic mortality occurring >15 d PC. Dead and moribund fish presented with lesions consistent with B. damnificus infection. A third challenge was performed to record histological changes associated with parasite development from initial exposure up to the cessation of mortality. Catfish (2–5 cm) were exposed as described above to a range covering 0, 35, 70, 100, 150, 175, and 215 cercariae/L. Each day, two fish were sampled from each treatment. Mortality trends were consistent with previous challenges. The mortality window coincided with parasite encapsulation, neovascularization, and development of the host‐derived cyst, suggesting that morbidity and mortality are linked to host pathophysiological changes in response to metacercariae encapsulation.     

Molluscicidal and antifungal activity of Erigeron speciosus steam distillate

The steam-distilled fraction of the aerial parts of Erigeron speciosus (Lindl) DC was tested for activity against strawberry plant pathogenic fungi Botrytis cinerea Pers ex Fr, Colletotrichum acutatum Simmonds, C fragariae Brooks, C gloeosporioides (Penz) Penz & Sacc, and the intermediate host snail Planobdella trivolvis that harbors the trematode, Bolbophorus confusus, that infests and causes severe infections in pond-raised catfish in the Mississippi Delta region of the USA. Bioautography on silica TLC plates demonstrated antifungal activity in the steam distillate. Preliminary bioassays of the steam distillate indicated the presence of phytochemicals toxic to P trivolvis. The bioactive compounds methyl 2Z, 8Z-deca-2,8-diene-4,6-diynoate and its 2E, 8E isomer were isolated by bioassay-guided fractionation and chromatographic techniques and identified by 1H NMR spectroscopy.