- We are trying to understand how insects are thinking, and it’s not the easiest task.  I mean sometimes we humans have a hard time understanding what we’re thinking ourselves, says Peter Hambäck professor at Department of Ecology, Environment and Plant Sciences, with a laugh.

A fruit fly.

In this new study the researchers wanted to find out how the insects reasoned when it came to different odors. Some odorants pull the insects towards objects, for example plants and some smells push them away. We humans want to be able to manipulate insects with odors for our own benefit, to mask human odors from insects that carry disease, such as malaria mosquitoes, or lower insect attraction to economically important crops.

 – A mixture of attractive and repellent odorants can have effects on the success of finding food, mates or were insects lay their eggs, says Peter Hambäck.

Researchers want to know where they reproduce and get their offspring (the source population) and what kind of habitats are well suited for them. There are other techniques for protecting plants that are used today- for example is that you plant a neighboring crop that pulls away the insects from a sensitive crop.

- In this study, we used fruit flies as a model organism, but the general mechanisms are likely the same also for other groups of insects. However, it would be interesting to compare responses on a larger range of insects, including those that are harmful to us, says Peter Hambäck.

The study revealed that the 25 flies, 3 days old of age (they die after little over a month) pushed into a wind funnel reacted by assessing the proportion of how much repellent there was compared to attractant. This was true for three of the four repellents tested. This means that the concentrations applied to crops is important but only in relation to the attractive odors. An interesting aspect seem to be that different repellents have a different neurological mechanism (in the neural system) causing different quantitative responses.

Imagine yourself being in the same situation as the insects, standing outside a bakery and smelling newly made buns and in the same time smelling garbage from a truck close by. What would you do? Would you still get that bun?

Read the open access paper “Scaling the interactive effects of attractive and repellent odors for insect search behavior” published in Scientific Reports here.