DOI: 10.5061/dryad.g1jwstqn5
title: Comparative toxicity of larvicides and growth inhibitors on Aedes aegypti from select areas in Jamaica

description: Insecticide resistance has become problematic in tropical and subtropical
 regions, where Aedes mosquitoes and Aedes-borne arboviral diseases thrive.
 With the recent occurrence of Chikungunya and the Zika virus in Jamaica,
 the Ministry of Health and Wellness, Jamaica, partnered with the United
 States Agency for International Development to implement multiple
 intervention activities to reduce the Aedes aegypti populations in seven
 parishes across the island and to assess the susceptibility of collected
 samples to various concentrations of temephos, Bacillus thuringiensis
 subsp. israelensis, (Bti), diflubenzuron and methoprene. Of the
 insecticides tested, only temephos has been used in routine larviciding
 activities in the island. The results showed that only temephos at
 concentrations 0.625 ppm and Bti at concentrations 6 – 8 ppm were
 effective at causing 98 – 100% mortality of local Aedes aegypti at 24
 hours exposure. Surprisingly, the growth inhibitors diflubenzuron and
 methoprene had minimal effect at preventing adult emergence in Ae. aegypti
 larvae in the populations tested. The results demonstrate the need for
 insecticide resistance testing as a routine part of vector control
 monitoring activies in order to determine useful tools that may be
 incorporated to reduce the abundance of Ae. aegypti.
description: The larvicide susceptibility of wild <i>Ae. aegypti</i> populations was analysed from seven of the eastern parishes in Jamaica, namely, St. Catherine, Kingston and St Andrew (KSA), St Thomas, St Mary, and St Ann. Ovitraps were established around 100 homes in each of the parishes through the period of September 17<sup>th</sup>, 2018 to December 7<sup>th</sup>, 2018 (permission to establish ovitraps around homes were aquired prior to initiation of work). Egg papers from ovitraps were taken to the Mosquito Control Research Unit, Jamaica, where they were periodically set to hatch per parish for bioassays under insectary conditions. Six wild populations of <i>Ae. aegypti</i> were established under insectary conditions, with one population per parish, with Kingston and St Andrew represented as one single population of <i>Ae. aegytpi</i>, given their spatial proximity. The larvae were reared to their larval 3rd instar stage and used for Bioassays. WHO larvae test kits obtained from Universiti Sains Malaysia (USM), Vector Control Research Unit, Infotech (Pinang, Malaysia), the only agency approved by the World Health Organization (WHO) to supply insecticide kits and materials for regular surveillance in public health. These kits were used as directed for Temephos, Methoprene and Diflubenzuron larvicide bioassays. 20 - 34 larvae were used per replicate per established population.  Mortality was observed and recorded at 1 hour and again at 24 hour. Each test was conducted with a control, which had 0.4% ethanol (supplied with the kits) Bioassays using the biolarvicide <i>Bacillus thuringiensis </i>subsp.<i> israelensis</i> (Bti) (VectoBac WDG) was was also conducted. A 10,000 ppm (mg/litre) stock solution of Bti was prepared by vigorously stirring using a magnetic stirrer (C MAG HS 7; IKA) and aliquoted to give concentrations of 0, 2ppm, 4ppm, 6ppm and 8 ppm of Bti in 2,000 ml of distilled water. 250 ml of each concentration was poured into disposable paper cups containing 20 – 34 larvae; care was taken to agitate the mixture prior to each pour to ensure particulates remained in suspension. Mortality was observed at 1 hour and again at 24 hour. The laboratory Aedes aegypti strain, Rockefeller was used as a reference strain for the all assays. Rockefeller were originally donated from the CDC, Atlanta.
description: Samples from Portland were donated by the ministry of health and
 wellness, Jamaica. larvae were then treated similarly
 to those reared in the insectary and also tested at their 3rd instar
 stage. File format Excel spreadsheet