The effects of diflubenzuron on a complex laboratory stream community

Abstract

Effects were assessed on the total biological community in complex laboratory streams caused by continuous exposure to diflubenzuron (1-(4-chlorophenyl)-3-(2,6-difluorobenzoyl) urea). The insect fauna suffered direct toxic effects at concentrations of 1.0 microgram/L and greater. The algal and fungal floras were mildly affected at the same concentrations; apparently indirect effects in response to the reduced herbivore and shredder components of the insect fauna. No effects were observed on the bacteria, oligochaetes or gastropods, at any of the test concentrations. Within the insect fauna, differences in sensitivities were observed: mayflies and stoneflies were affected at 1.0 microgram/L, dipterans were affected at 10.0 microgram/L, and coleopterans were apparently unaffected at any of the test concentrations. Effects on caddisflies could not be determined due to their failure to become established in the stream systems. These differences between insect orders in sensitivity, coupled with differences in generation time, may reduce the overall benefits of the insecticide. For example, if diflubenzuron is used for chironomid control, the result may be more severe and longer lasting effects on nontarget mayfly and stonefly populations.

Advances in Microbial Ecology

“…Quite commonly, 20-gallon aquaria have been used with considerable success (Giddings and Eddleman, 1978;Sikka and Rice, 1973). Long fiberglass troughs, approximately 30 cm square and 6 to 12 m long (S. R. Hansen and Garton, 1982;McIntire, 1965), have been used to model streams. Terrestrial systems also span a large size range from 40-cm 3 glass or plastic columns (Draggan, 1977;Jackson et al, 1977) to large glass boxes with volumes in excess of 800 cm 3 Gillett and Gile, 1976).…”

“…Similarly, the toxicity of a pollutant to grazers (snails, in this case) can be examined for "domino" effects on microbial mineralization rates and ultimately periphyton dynamics. Interpretation and field extrapolation of the results from stream microcosms exposed to a pesticide (S. R. Hansen and Garton, 1982) and to fuel oil (Bott and Rogenmuser, 1978) could probably be enhanced by applying the McIntire model.…”

“…These studies have provided ideal, but largely untested, laboratory systems for assessing the relationship between the fate and effects of pollutants and the activity of microbial communities. S. R. Hansen and Garton (1982) and Maki (1980) have shown their potential use in assessing the toxi-cological effects of the pesticides diflubenzuron (a chitin-synthesis inhibitor) and trifluoromethyl-p-nitrophenol (a lampricide), respectively. Giesy (1978) has demonstrated, using a microcosm, the toxicity of cadmium to leaf litter colonization of bacteria and fungi and to its eventual decomposition.…”

A simple stream‐side test system for determining acute lethal and behavioral effects of pesticides on aquatic insects

“…Researchers investigating the potential risks of pesticide contamination to stream invertebrates have employed various test systems designed to more closely reflect natural conditions than do conventional laboratory bioassays [ 11. Laboratory streams have been useful in studying pesticide effects on stream insects but are usually elaborate, costly, and, to some extent, artificial [2,3]. A number of field-testing systems have been devised in an effort to approach more natural conditions, including various multiple-trough systems with inflow from diverted stream water [4,51 and experimental stream channels [6,7].…”

O uso de praguicidas nas atividades aqüícolas: destino e efeitos após aplicações em tanques experimentais e avaliação nas pisciculturas e pesqueiros da bacia do rio Mogi-Guaçu

“…Entretanto, as respostas da comunidade fitoplanctônica frente a um evento de contaminação por inseticidas não parecem seguir um padrão, e os dados disponíveis na literatura exibem certa controvérsia. De maneira geral, os efeitos sobre a comunidade fitoplanctônica parecem estar mais relacionados às alterações nos níveis tróficos superiores que propriamente aos efeitos diretos (HULBERT et al, 1972;CROSSLAND et al, 1982;HANSEN e GARTON, 1982a, 1982bDAY et al, 1987;TIDOU et al, 1992;BOYLE et al, 1996). Certas técnicas de manejo na atividade aqüícola visam à manipulação da produção da comunidade zooplanctônica, promovendo a maximização de itens alimentares específicos (PIASECKI et al, 2004).…”