Effects of Cutrine-Plus® algaecide and predators on wood frog (Lithobates sylvaticus) tadpole survival and growth

Copper contamination is increasing in many aquatic ecosystems. One mode by which copper can be introduced into aquatic ecosystems is as an algaecide, such as Cutrine-Plus®. Using a mesocosm experiment, we examined the effects of Cutrine-Plus® on wood frog (Lithobates sylvaticus) tadpoles. In addition, we examined how the presence of a nonnative predator the Western mosquitofish (Gambusia affinis) may interact with exposure to Cutrine-Plus®. Exposure to our low and high Cutrine-Plus® treatments had a strong negative effect on the wood frog tadpoles, and survivorship was greatly decreased in the low treatment, and no tadpoles survived in the high treatment. Additionally, the tadpoles that survived the low treatment were significantly smaller than those in the control treatment. Mosquitofish had no effect on the survivorship or growth of wood frog tadpoles, and mosquitofish presence did not have a significant interaction with the Cutrine-Plus® treatments. Cutrine-Plus® clearly had a negative effect on wood frog tadpoles at the concentrations used in our experiment, which were at and below the label-recommended dosages, suggesting that the use of Cutrine-Plus® in natural ponds may have negative consequences for wood frog populations and possibly other amphibians.     

Terminal double bonds in the alkenes and acetates of defensive secretion from the thrips Suocerathrips linguis Mound & Marullo, 1994 (Thysanoptera: Phlaeothripidae)

Defensive secretions of adult males and females of the subsocial thrips Suocerathrips linguis were examined using gas chromatography–mass spectrometry (GC–MS). The samples contained six long-chain acetates and five aliphatic alkanes and alkenes. Whole-body extracts yielded six methyl esters of fatty acids as well as hexadecyl acetate. Structures of the two main components, (11Z)-icosa-11,19-dienyl acetate and octadecyl acetate, were confirmed. The third most abundant substance was identified as octadec-17-enyl acetate, which is a new natural product. In addition, (9Z)-octadec-9-enyl acetate was identified along with other acetates. Pure icosadienyl acetate was found to remain liquid down to −15°C, and is the solvent for the solid components of the secretion cocktail. A tentative biosynthetic pathway for all of the 12 acetates, alkanes and alkenes is discussed, considering especially the components with terminal double bonds that are uncommon in Thysanoptera and other insects.     

Consequences of Embryonic UV-B Exposure for Embryos and Tadpoles of the Plains Leopard Frog

Abstract: In organisms with complex life cycles, understanding the effects of environmental change requires investigating the possibility that the effect of such change on one stage will have consequences for other stages. We investigated the effects of embryonic exposure to UV-B radiation on embryo and tadpole development of the plains leopard frog (   Rana blairi ). Embryos were exposed to sunlight filtered to provide two levels of UV-B exposure (e.g., at 310 nm: high exposure is approximately 84% transmittance and low exposure is approximately 58% transmittance). Hatching success of embryos exposed to different UV-B levels did not differ. Tadpoles resulting from exposed embryos were raised at three densities. Growth and development were slower in tadpoles exposed to higher UV-B levels as embryos. Density negatively affected growth and development. Survivorship did not differ among UV-B or density treatments. Our results suggest that even if lethal effects are not exhibited at one stage, sublethal effects may manifest themselves at other stages, possibly affecting the long-term success of exposed individuals and populations.