2. How PICS Bags work …

3. Key facts about insect respiration - Insects require oxygen - Have high metabolic rates

5. 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?

6. Normoxia – space bag with mesh Hypoxic – space bag

7. Healthy 3 rd instar bruchid larvaDesiccated 2 nd instar larva

8. Methods - Callosobruchus maculatus 2. Feeding behavior – Purdue Insect Feeding Biomonitor 3. Sealed containers – septum bottles 1. O 2 /CO 2 concentrations – Mocon head-space analyzer

11. Hypoxia or Hypercarbia - Feeding CO 2 alone

12. Hypoxia or Hypercarbia - Feeding O 2 alone

13. O 2 consumption and CO 2 production O 2 consumption and CO 2 production per bruchid (first instar larva till adult emergence)

15. 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

16. C 6 H 12 O 6 + 6O 2  6CO 2 + 6H 2 O

18. 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.

19. 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!

20. Thanks especially to Venu Margam Dick Shade Ibrahim Baoua Susan Balfe