In experiments at the Co Do rice±fish research
station, the maximum weed biomass obtained was
just 5.31 g dry weight m±2 (Rothuis, Duong, Richter
& Ollevier 1998), leaving little for T. pectoralis to eat.
The little there is has to be shared with B. gonionotus,
a macrophyte feeder. It is therefore striking that
B. gonionotus has a much higher SGR than
T. pectoralis. In rice fields, B. gonionotus mainly
feeds on plant material (Rothuis et al. 1998). As the
weed biomass is low, this implies that B. gonionotus is
feeding on rice. Indeed, at the Co Do rice±fish
research station, we found a lower number of rice
panicles when B. gonionotus was stocked in rice fields
(N. Vromant, unpublished data).