An important aspect in mass rearing biocontrol agents is providing them with a suitable food source. Optimization of a very commonly used food source, the Mediterranean flour moth Ephestia kuehniella, has been done extensively over the years but one problem has not been tackled thus far, allergies. People working intensively and for long periods of time with E. kuehniella are at risk of developing allergies or even forms of asthma. One of the biggest problems are the scales that cover the entire body of the moth. They are very small and can easily be lost, thereby becoming airborne and entering the airways.
In my project I am looking at a particular mutant strain of E. kuehniella, scaleless (scl), in which the females have scaleless wings whilst males have normal scale-covered wings. The main task is to figure out why only females have scaleless wings. To see how scalelessness is inherited I have done many crosses between the scl strain and other strains and I am currently setting up many more. E. kuehniella has a WZ/ZZ sex determining system, in which females have a W- and a Z chromosome and males have two Z chromosomes but no W chromosome. Because the W chromosome can only be found in females the easiest explanation for female-specific scaleless wings is that the scaleless mutation is linked to the W chromosome. However, my first rounds of crosses indicated that scalelessness is not connected to the W chromosome as fathers from the scl strain can produce scaleless daughters with females from other strains. The regulatory mechanism behind the female-specific expression of the scaleless mutation thus seems to be more complicated.
The crosses are also used to quantify the effects of scalelessness on life history traits like fecundity and larval survival. These traits are important to measure because a scaleless strain would only be useful in biocontrol rearing facilities if the production of eggs is efficient and of high quality. In addition to the inheritance and life history traits I am also exploring environmental effects, for example temperature and humidity, on the scaleless phenotype. This part of the project thus involves a lot of counting. “Luckily” the development time of Ephestia is quite long which gives me some time between generations to work in the lab to isolate candidate genes involved in wing-scale development.
Of course I am not alone in the lab and I would like to thank my supervisor František Marec for teaching me everything I know about Ephestia culturing and my colleagues here in the institute for their help in the lab and brightening the days when the experiments are troublesome.