Most thrips can only colonize and breed on plant leaf substrate. Get young seedlings or plant branches to observe. To carry out a bioassay you need to select at least 4 leaves of the plant take initial count of their numbers and apply the toxicant on the 4 leaves then count mortality after 12, 24 or 48 hours exposure. Remember to have a control of similar replicates.

Dear Emmanouil

Hi,

IRAC website has introduced the different bioassay methods based on the various insect pest. Follow below link to see one of these guidlines.

http://www.irac-online.org/methods/frankliniella-occidentalis-adults/

Best regards

To some extent it all depends on your goal and target audience.

  For example: My goal is to monitor insecticide resistance. The target audience will most be other research scientists. Thus I will use methods like leaf dip assays to keep the variability due to application method to a minimum. This will greatly improve my ability to detect differences.

  For example: My goal is to see if Thripsaway brand is better than Bug-B-Gone in controlling thrips. In this case I want to suggest to growers that one of these products is better than the other. A leaf dip assay in this case is inappropriate because the grower will never dip his crop. The crop will be sprayed, or the product applied as a soil drench, or some such method. So here I need to make sure that the way that I apply the insecticide is relevant to how the grower will apply the insecticide.

If you have never done this type of assay before, I suggest that you plan on at least one trial run. Given that formulation and formulation adjuvants will influence product efficacy, it is very difficult to sit at a desk and choose the dosages that will make the best dose-response experiment. If this is a field trial, then use the lowest recommended label rate. You want some of the products to fail. If all treatments have 100% mortality then there are no treatment differences to discuss.

If the goal is to use insecticide treatments to manage a disease vectored by thrips, then you need more detailed methods. The problem is field applications are never 100% effective, and they are not permanent. However, with a good choice of insecticide and good planning (suitable application method, and area wide coordination) the tactic can be effective. A key piece in this effort will be to understand how the thrips feed, and how the insecticide affects thrips feeding. Issues like repellency and how feeding patterns change as the applied lethal dose degrades over time in the field to produce sublethal doses.

@ Daniel Mutisya, is it possible to take the reading at 12, 24 or 48 hours. Because many were recommended to take reading within 24 hours.