Reactions of the Larvae of Three Rheophilic Species of Trichoptera to Selected Insecticides

Abstract

Procedures are outlined for evaluating in aquaria the effects of insecticides against rheophilic species of Trichoptera larvae (Brachycentrus lateralis (Say), Hydropsyche morosa Hagen, and H. recurvata Banks). In general DDT, DDD, and methoxychlor were considerably more toxic than were malathion, Baytex®, or diazinon and their regression lines were steeper. Some of the methoxychlortreated larvae recovered within 18 hours after treatment but the reverse was true for DDT, DDD, and the organophosphates. DDT dissolved in ethanol was considerably more toxic than any of the three commercial formulations of DDT tested. Sensitivity to DDT declined (i.e.LC50 values were higher) with increasing size (age) of the larvae. LC50 values of DDT also varied directly with the densities of tested populations in tests containing more than 10 larvae per 250 ml of water. Toxicities of all chlorinated hydrocarbons varied indirectly with the temperature and those of the organophosphates directly. The significance of these findings to laboratory and field tests is discussed.

The feeding behaviour ofSimuliumlarvae, and the development, testing and monitoring of the use of larvicides, with special reference to the control ofSimulium damnosumTheobald s.l. (Diptera: Simuliidae): a review

“…The effects of temperature varied according to the class of compound. Thus, toxicity of all organochlorines to Trichoptera larvae varied inversely with temperature, while that of organophosphorus compounds varied directly (Fredeen, 1972). These temperature findings are supported by the work of Yasuno et al (1978) on Crustacea and to some extent by Sanders & Cope (1966) on Cladocera, and are paralleled by findings on the target simuliids previously discussed.…”

“…Such testing has been carried out most elegantly in a long series of studies by Muirhead-Thomson (1973, b, c, 1979, who also reviewed the subject in detail (1971). Other important works on this aspect are Fales et al, 1968;Fredeen, 1972;Jensen & Gaufin, 1964a, b;Sanders & Cope, 1966, 1968Rodrigues et al, 1983;Yasuno et al, 1978). All such studies are of limited applicability and, as Wallace & Hynes (1981) state, "approaches used in laboratory testing make predictions of community dynamics of benthos in running waters difficult, if not impossible".…”

Effect of particulate Abate insecticide on invertebrate stream drift communities in Newfoundland

“…30 Small larvae of Hydropsyche morosa were more susceptible than larger larvae of the same species. 0.02 ppm DDT killed 50 percent of small larvae (about 19.0 mg in weight) in six hours compared with 40 hours for larger specimens (32.5 mg).…”

EFFECT OF TEMPERATURE AND STAGE OF DEVELOPMENT ON SUSCEPTIBILITY OF AEDES EUEDES AND AEDES STIMULANS (DIPTERA: CULICIDAE) LARVAE TO TEMEPHOS

“…It is generally recognized that fourth-instar larvae of mosquitoes are more tolerant to organophosphorous larvicides than earlier instar larvae (Mulla 1961;Thomas 1965;Wilder and Schaefer 1972;Rettich 1976). It is also accepted that susceptibility to organophorous insecticides increases with increasing temperatures (Fredeen 1972;Back et al 1979;Yasuno et al 1978).…”