Phytoecdysteroids and Ostrinia nubilalis

Why !?

European corn borer  adult female.		 In the past years, we focused our research on European corn borer (ECB). This insect is considered as polyphagous (recorded on over 200 plant sp.) and can be found all over the world, in Europe as well as in North America. It is considered as a major pest of corn. A wealth of data is available on this insect, from ecological to physiological observations. In addition, it is easily bread in the laboratory on an artificial diet.

We discovered that ECB larvae actively avoid food to which ecdysteroids are added. They detect them with their  taste receptors. This is interesting because if this effect is confirmed, we could use ecdysteroids to enhance the resistance of their host plants.

 

 Larval behavior

Larvae were offered a 
choice between a control 
(blue) and a treated substrate (red)

 

Legend:
blue = nb eating control
red = nb larvae eating treated food
pink = nb larvae eating both control and treated
white = nb larvae not eating at all

Larvae avoid food treated with 20-hydroxyecdysone (20E), in direct relation to the dose of 20E  (Marion-Poll et Descoins, 2002). L1 larvae are repelled by 20E which is toxic to them [work of Cécile Faucher & Adil Yattaf].

 

 Electrophysiology

Each galea
bears 2 taste
pegs

Legend:
 number of action potential per second (ordinates) recorded with an electrode slipped over the lateral peg, containing 20E at different concentrations (abcissa, log10 molar units).
Larvae are equipped with taste receptors detecting 20E at a low concentration (< 10-6 M) [Marion-Poll and Descoins, 2002]. Adult females also detect 20E with taste sensilla on their tarsi [work of Delphine Calas].

 

19/01/2014