I am interested in questions concerning cheating and how mutualistic
interactions are maintained, especially plant-pollinator interactions.
During my PhD thesis I studied the behavior of nocturnal hawkmoths
confronted with rewarding and non-rewarding Petunia flowers, both
under controlled and field conditions. For this purpose I bred Petunia
lines with low nectar volume but otherwise resembling the rewarding
phenotype (P. axillaris). The goal was to obtain lines with less nectar
(low nectar line) than P. axillaris suitable for behavioral assays and
fitness analyses. 

Before low nectar lines were usable, I conducted behavioral assays
in the lab and in the field with Petunias where nectar was manually
extracted. I could observe that before probing, hawkmoths did not
preferentially select the rewarding type, independent on their state
of experience. The number of flowers visited by moths was only
occasionally reduced on non-rewarding plants. This behavioral
response seems to be dependant on the population density of native
P. axillaris (Brandenburg and Bshary 2011). The drinking duration of
moths per flower was the only behavioral response that was consistently
reduced on plants that contained no nectar. I could observe the same
behavioral alterations of hawkmoths using the low nectar lines
(no difference in first choice and N flowers visited; significant reduction
of drinking time) and assessed one parameter of plant fitness: seed set.
Low nectar lines pollinated by hand produced significantly more seeds
han hand-pollinated P. axillaris. However this effect was neutralized when
pollination was executed by hawkmoths.

In collaboration with Giorgina Bernasconi and Sara Carlson, I recently
started a project comprising behavioral observations and paternity
analysis of P. axillaris and low nectar lines in the field.