Normoxia – space bag with mesh Hypoxic – space bag UNKNOWNS How much O 2 does the cowpea bruchid consume? Do O 2 and CO 2 affect feeding? Developmental stage differences in susceptibility ? Where do bruchids get their water?
Normoxia – space bag with mesh Hypoxic – space bag
Conclusions - Callosobruchus maculatus The insect uses ~ 8-9 ml O 2 during development Drop in O 2, not rise in CO 2, affects the feeding behavior The bruchid larvae are burning carbohydrates Role of water in combination with O 2
What happens in a PICS bag? Insects infesting the grain draw down the oxygen and raise the carbon dioxide level. The drop in oxygen cause the insects to cease feeding and go into a state of suspended animation. Not feeding means not growing and developing and most important of all, not reproducing. Not reproducing means the population doesn’t expand, which means a serious problem never develops.
Bruchid Population Expansion – Why PICS bags work 1 pair of adults at start of storage 30 days later – 50 pairs 60 days later – 2500 pairs 90 days later – 6,250,000 pairs If you arrest feeding, growth and development and reproduction in the first 60 days or so, a serious problem never develops. PICS bags do that – at low cost, simply, using bags that are durable and manufactured in Africa, without insecticides Bottom line – you don’t have to kill insects to control them!
Thanks especially to Venu Margam Dick Shade Ibrahim Baoua Susan Balfe