Laboratory experiments were done to determine the effect of geochemical composition of diatomaceous earth (DE) on insecticidal activity of DE against adults of the rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae). Samples of DE were mined from DE-deposits in Slovenia, Greece, and Serbia. In addition, a commercially available DE formulation (SilicoSec Ò ) was used in the tests and served as a positive control. The bioassays were carried out at temperatures 20, 25, and 30°C, relative humidity levels of 55 and 75%, and at application rates of 100, 300, 500, and 900 ppm. Adult mortality was recorded after 7, 14, and 21 days of exposure. Prior to bioassays with S. oryzae, the geochemical composition of all DEs that were used in the tests was determined by whole rock ICP geochemical analyses.Silica (in the form of SiO 2 or opal-A) was the DE ingredient that was significantly correlated with efficacy in most of the bioassays. Some weak positive correlation was observed between S. oryzae mortality and MnO or CaO content. All significant correlations between mortality
The nontarget effect of Steinernema feltiae, Steinernema carpocapsae, Heterorhabditis bacteriophora, and three mixed suspensions of two species of entomopathogenic nematodes on the larvae of the twospotted lady beetle, Adalia bipunctata (L.) (Coleoptera: Coccinellidae), and on the larvae of the lacewing Chrysoperla carnea (Stephens) (Neuroptera: Chrysopidae), were studied in a laboratory bioassay. The assay was performed at three temperature (15, 20, and 25 degrees C) and at three different concentrations of the suspension (500, 2,500, and 5,000 infective juveniles [IJs]/ml). The larvae of A. bipunctata were more susceptible to nematode attack than the larvae of C. carnea. Four days after treatment, significantly the lowest mortality of A. bipunctata and C. carnea larvae was recorded at 15 degrees C, whereas no significant differences were noted between 20 and 25 degrees C. At 500 IJs/ml, the nematodes had significantly the lowest nontarget effect on the larvae of both aphid predators, whereas no significant differences in this regard were established between 2,500 and 5,000 IJs/ml. We conclude that the entomopathogenic nematodes under investigation exhibit a pronounced nontarget effect on the larvae of both predators mentioned.
In a paper the results of insecticidal activity of two known insecticides (deltamethrin and imidacloprid), thujone and essential oil of rosemary against the larvae and adults of sycamore lace bug (Corythucha ciliata) are presented. The experiment was conducted in a laboratory, under room conditions. We tested the activity of each product in three different concentrations. The most desirable insecticidal activity had deltamethrin, which caused almost 100 % mortality of both developmental stages of the pest at all three concentrations. Succeeding products were imidacloprid, which caused 89.6 % larval mortality at recommended concentration, and essential oil of rosemary, which caused 81.7 % adult mortality at 1 % concentration. Larvae of sycamore lace bug were significantly more susceptible to tested products than adults. Significantly the lowest mortality was determined one day after treatment (41.7 %), while the highest mortality was stated three days after treatment (71.3 %). For future reduction of the damage caused by the studied pest on plane trees, we recommend the application of thujone and essential oil of rosemary, which appeared to be environmentally more acceptable substances. In our study both agents showed a middle satisfying activity in controlling larvae and adults, but they have also obvious repellent activity, which leads to their better efficacy in the open.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.