Insecticidal Effect of Pătârlagele Diatomaceous Earth Against Acanthoscelides Obtectus Adults

Abstract

In the present study there are presented the results obtained in laboratory tests to evaluate the efficacy of the Romanian diatomaceous earth from Pătârlagele deposit in Buzău County (DE PatRom) against adults of three population of the bean weevil Acanthoscelides obtectus L. (one maintained in laboratory conditions at the Plant Protection Institute Bucharest and the others two came from fields bean from Buzău and Bacău) compared with two commercial formulations (SilicoSec® and PyriSec® ). The DE PatRom was applied at four doses 100, 300, 500 and 900 ppm while SilicoSec® and PyriSec® at the doses registered in common practice. Tests were carried out at 25±2°C and at 70± 5% relative humidity (RH). Adult mortality was assessed 3, 7 and 14 days after treatment. The PyriSec DE was the most effective reaching a total mortality of adults for all three insect populations tested even after 3 days, followed by SilicoSec DE which caused mortality between 74 and 99% after 3 days and 100% after 7 days. The mortality levels of A. obtectus adults reached by Romanian DE PatRom varied depending on dose, period after treatment and insect population. The mortality of bean weevil increased with increasing dose and period after treatment. The highest mortality (of 93, 96 and 98.5% to adults in Buzău, Bucharest and Bacău population, respectively) was recorded in bean treated with 900 ppm after 7 days. The results in experiments showed that the A. obtectus adults of Bacău population were more susceptible and those of Buzău population were more tolerant to all DEs tested.

Introgression and Stability of Common Bean Weevil (Acanthoscelides obtectus [Say]) Resistance in Diverse Market Classes From the Andean Gene Pool of Common Bean

“…Weevils can be managed by use of chemicals, non-chemical treatment of grain, biological control, and improved postharvest storage (Cardona 2004;Chireceanu et al 2022;Mutungi et al 2015); however, these methods are not always available and not sustainable (Blair et al 2010), as resource-poor smallscale farmers produce most of the beans in Africa. For instance, some farmers in Eastern and Southern Africa use strategies such as solarization, sieving, admixing grain with ash, fine soil, granary hygiene, use of different storage methods and botanical products that exert some fumigant activity, contact toxicity or repellency, and oviposition-deterring properties to manage and control bean weevils (Abate and Ampofo 1996;Paul et al 2009); however, the efficacies of these indigenous methods are low as there exists no standard application guidelines, and their use is only practical for preserving smaller quantities of seed (Stathers et al 2008).…”