Methanolic extracts of aerial parts of the medicinal plant Argel (Solenostemma argel (Del.) Hayne), incorporated into rearing media of Culex pipiens L. showed effect on oviposition, egg hatchability and larval viability. Acute toxicity of S. argel extract was found to possess LC(50) of 0.037, 0.031, 0.009 and 0.007 ppm and the LC(95) was found 0.394, 0.293, 0.065 and 0.030 ppm, after 1, 2, 4 and 7 days against the larva of C. pipiens under laboratory conditions. The ovicidal effect of S. argel was relatively less pronounced, however, the 0.1% concentration reduced egg hatch by 33.7%. The mortality of the newly hatched larvae, reared from eggs in this media, reached 100% at concentrations as low as 0.025%, 2 days post hatching. Complete suppression of oviposition within the first 2 days was observed, however its action was gradually lost thereafter. Bioactive effects were mainly attributed to the presence of a variety of bioactive organic substances mainly terpenes, pergenine glucosides, alkaloids and sterols.

No abstract

Toxicity of the aqueous extracts of Rhazya stricta Decne, Calotropis procera (Ait.) Cass., and Francoeuria crispa (Forssk.) R.Br. leaves against larvae of Culex pipiens L. mosquitoes was investigated by incorporating the extracts into egg and larval rearing media. Acute LC 50 were 270 and 322 ppm for R. stricta and C. procera, respectively. The chronic toxicities for R. stricta at concentrations 0.02 and 0.04 percent, reached 70 and 100 percent larval mortality, respectively, and 91.1 and 100 percent at concentrations of 0.05 and 0.075 percent, respectively, for C. procera. Both materials conferred significantly reduced larval development and thus, consequently reducing pupation and adult emergence. Only 10 and 33.3 percent of the larvae reared in media containing 0.02 percent of R. stricta water extract and 0.025 percent of C. procera completed development to the pupa stage. None of the larvae in R. stricta extract reached adulthood and only 20 percent of the larvae did in the C. procera extract. The highest concentration of F. crispa tested (0.25%) caused only 55.3 percent mortality after 10 days, leading to 34.3 and 21.2 percent successful pupation and adult emergence, respectively. No mosquito eggs were laid in media containing at concentrations Ն 0.05 percent aqueous extract from any of the three plants. Application of R.

Trials were conducted on spring-transplanted (13 May) broccoli (cv. Green Comet) at the Horticulture Field Research Center in Ft. Collins, CO. Individual plots consisted 20 ft long single rows with 15-in in-row spacing, arranged in a randomized complete block design with four replications. Insecticide applications were made 3 Jun and 21 Jun using a CO2 compressed air sprayer delivering 15 gpa at 30 psi in two passes directed along the sides of the planting. An organosilicant spreader (Kinetic, 6 fl oz/A) was added to all treatments. Evaluations were made by visual observations of flea beetles on six plants/plot.

Trials were conducted at the Colorado State Horticulture Research Farm, Ft. Collins, CO on transplanted peppers. Emphasis of the trial was to evaluate treatments that were accessible to home gardeners or showed interesting “bio-rational” insecticide characteristics. Individual plots consisted of 8 plants, on single-row beds at approximately 15-in spacing. Plot design was a RCB with 4 replications. Applications of sprayed treatments were applied as a single pass on each side of the plants with CO2 compressed air sprayer directing spray to the leaf underside. Dust applications of sulfur (FloTox Garden Sulfur) were applied with a Dustin-Miser applicator. Evaluations of psyllid populations were made by counting all insects on the center four plants of each plot.