We evaluated larval and adult susceptibility to 5 insecticides commonly used for control of Aedes albopictus, by using 15 field-collected populations from northern and central Italy, and we compared these data, collected in 2002, with those from evaluations conducted in 1992-93, 1996, and 1998-99. Larvae were tested for susceptibility to temephos and to the conventional diagnostic dosages of ch...

BACKGROUND Transgenic corn hybrids that express toxins from Bacillus thuringiensis (Bt) have suppressed European corn borer populations and reduced the pest status of this insect throughout much of the US corn belt. A major assumption of the high-dose/refuge strategy proposed for insect resistance management and Bt corn is that the frequency of resistance alleles is low so that resistant pests ...

After controlling Triatoma infestans in Brazil, other species of triatomine that were considered minor in the transmission of Chagas disease became important. The persistence of Triatoma brasiliensis in Northeastern Brazil, associated with reinfection of domestic environments recently sprayed with pyrethroids, may be a signal of susceptibility alteration of this species to this insecticide. Spe...

The acute oral toxicity test seeks to estimate the dose at which 50% of the organisms in adefined population will die (LD50) after exposure to a test material. The statistical basis for the classicstudy design was first described in the 1920s and remained in use until current times. In this test,groups of animals were administered varying doses of test material, and a dosed animal either lived ...

Western corn rootworm, Diabrotica virgifera virgifera LeConte, neonate susceptibility to clothianidin, a contact and systemic neonicotinoid insecticide, was determined from both laboratory and field-collected populations. Neonates were exposed to filter paper treated with increasing clothianidin concentrations and mortality was evaluated after 24 h. Additionally, two populations were exposed to...

Public concern over the use of laboratory animals has increased in recent years. Laboratory animal procedures involving unrelieved pain and distress (e.g., the footpad injection of rodents with Freund's adjuvant), which were routine in the past, now require strong justification. Moral concern is reflected in the existing legislation on animal experimentation in the United States (CFR 1992) and ...

In this study, contact and fumigant toxicities of methanol extracts and essential oils of Salvia tchihatcheffii and S. cryptantha plants against two main storage pests Sitophilus granarius L. and S. oryzae L.were tested. Evaluation of the results showed that the highest activity was obtained from S. tchihatcheffii plant. Stem extract of this plant had an insecticidal activity of 87% on S. grana...

Efficacy of the methanol extracts from fruits without seeds, whole yellow ripe fruits and seeds of the plant Solanum xanthocarpum was evaluated against larvae of Anopheles culicifacies, Anopheles stephensi, Aedes aegypti and Culex quinquefasciatus, the important vector mosquitoes prevalent in the arid region. Experiments were carried out on late 3rd or early 4th instar larvae of these mosquitoe...

Every year thousands of new substances are synthetized and marketed. Either by regulatory demands or scientific purposes, these substances should all be tested. The determination of lethal concentration (LC) in a given population after toxicity testing in the laboratory is still the best way to establish and compare toxicity. In this technical note, we propose an R function to estimate LC with ...

We assessed the toxicity of ammonia ions to Stentor coeruleus and Coleps hirtus (Protozoa) isolated from activated sludge taken from two municipal wastewater treatment plants in southern Poland. Stentor coeruleus is a rarely occurring species in activated sludge, unlike the widespread Coleps hirtus. The mean LC50 values (concentration causing 50 % mortality) calculated for the 24 h tests differ...