Bioassays for Monitoring Insecticide Resistance

The overall goal of the following experiment is to determine if the insect has developed resistance to the insecticide. This is achieved by making concentrations to be tested by dissolving technical grade insecticide into acetone for contact insecticides as described by plaid AL in 1987. Or honey water solution for systemic insecticides as described by snores Etol in 2008.

As a second step, Eloqua 0.5 milliliters of the acetone insecticide solution into a 20 milliliter glass insulation vial, and rotate vials on a commercial hotdog roller with the heating element turned off or Eloqua 0.5 milliliters of the honey water insecticide solution onto a piece of floral foam placed inside a vial. Next, collect the desired insect for the adult vial test in order to conduct the bioassay, which monitors for insecticide resistance results are obtained that show whether or not the insect has developed resistance to the insecticide based on comparing the lc 50 achieved via probate analysis to pre-existing lc fifties. Hello, my name is Audra Miller.

I'm from the University of Missouri College of Agriculture, food and Natural Resources Delta Research Center in Portageville, Missouri. I'll be conducting an experiment out of Dr.Kelly Kindle's entomology lab. I'll be showing the procedure to detect whether or not insecticide resistance is occurring.

Now let's get started. It is imperative to use proper safety precautions like safety goggles, masks and gloves, et cetera. When handling insecticides, consult the material safety data sheet for the recommended personal protective equipment of the specific pesticide being tested.

In order to make a stock solution, adjust for purity and measure technical grade insecticide in a way. Boat in the hood partially fill a volumetric flask with acetone. Add the insecticide, rinse the whey boat with acetone into the flask.

Fill the volumetric flask to the graduation line with acetone mixed by inverting several times. Make serial dilution as required color code the vials for the concentrations using paint or markers. Pour approximately half the volume as the number of vials to be made in a small beaker when the solution is not in use, cover it to minimize evaporation.

Use a repeater pipetter to deliver 0.5 milliliters to the vials. Work from low to high concentration, starting with the control of acetone only in order to coat the inside of the vial with the technical grade insecticide. Place vials on a commercial hotdog roller with the heat turned off.

Allow the vials to rotate until all the acetone has evaporated. Examine each vial individually to ensure dryness. Gather the insects to be tested using pheromone traps, sweep nets, or any other means of mass capture.

Provide insects with food and moisture for eight to 24 hours. Select healthy active specimens for the bioassay with 10 to 25 insects per test.Concentration. Place insects in the vials such that they're exposed to the full range of the concentrations, not just one concentration at a time.

After appropriate incubation time, assess mortality based on criteria of coordinated movement, such as the ability to write itself if placed on its s dorsal surface or coordinated movement when gently prodded. If the insect can write itself but falls over, there is no coordinated movement, so the insect should be assessed as dead. Record the number of live and dead individuals and calculate the percent survival for all concentrations.

Prepare vials with the technical grade insecticide dissolved in 10%Honey water solution weigh honey to make a 10%by volume honey water solution transfer to a volumetric flask and add technical grade insecticide to the honey water solution and rinse the way boat. Repeat the process of making cereal dilution, but use honey water instead of acetone. Cut a piece of floral foam and place inside the vial Eloqua.

Point five milliliters of solution onto the floral foam enclos insects with a cotton ball instead of a lid. Conduct the bioassay in the same manner as you would with the contact insecticides correct for mortality in the control. According to Abbott, determine the lethal concentration required to kill 50%of a population and 95%confidence intervals.

This can be performed using a software program like SAS Proc probate or Polo Plus, for example, in this sample program for SAS dose represents the concentration used in the bioassay. N is the number of individuals tested at a given concentration and response is the number of dead individuals find the probability of 0.5 and this is the lc 50 with confidence limits of 0.1891 to 0.3273 micrograms per vile. If baseline data exists for the insect tested or an lc 50 obtained from a known susceptible population, the new lc 50 can be compared to the lc 50 of baseline data or susceptible populations.

If the baseline lc 50 was 0.1487 micrograms per vile with confidence limits of 0.1167 to 0.1793 micrograms per vile, one could conclude there was a significant change in resistance because the confidence limits do not overlap. However, if the baseline lc 50 was 0.1487 micrograms per vile, but the confidence limits were 0.0958 to 0.1983 micrograms per vile, there would not be a significant increase in resistance because the confidence limits overlapped. This experiment can be used to help tell if insecticide resistance is a cause for the insecticide failure or not, but remember when working with insecticide, you should always use the proper protective equipment.Now.

Thanks for watching and good luck with your experiments.