Table 2 Most frequent pollinator species of cotton in Burkina Faso and their effectiveness in terms of fruit set and quality parameters (n = 300 flowers; N = number of pollinator visits). Apis mellifera is a semi-wild honeybee species (i.e. some colonies are managed, while others are feral), all other species are wild bees. 4 species of wasps (Scoliidae) were observed as effective pollinators, the species were pooled due to very low number of visits. Wild bees with less than ten flower visits were pooled and analysed as remaining wild bees. Bold values refer to significant effects. Effect of field (random factor) was calculated using Chi square statistics.

From: Bee pollination increases yield quantity and quality of cash crops in Burkina Faso, West Africa

Fixed effects Fruit set Non-intact seeds Seed weight Fibre weight N
z P t P t P t P
    Apis mellifera 2.48 0.013 7.94 0.013 13.70 0.004 13.57 0.005 150
    Ceratina spec.1 −0.23 0.820 −0.13 0.900 −1.01 0.312 −1.70 0.091 15
    Hypotrigona gribodoi 0.07 0.948 −0.34 0.736 0.10 0.919 0.17 0.862 11
    Tetralonia fraterna −0.55 0.582 −3.43 0.002 2.67 0.008 2.83 0.005 59
    23 remaining wild bees (pooled) 0.28 0.781 −1.57 0.133 0.02 0.984 −0.77 0.443 49
    4 Scoliidae wasp species 1.80 0.073 −0.42 0.676 −0.80 0.423 −0.43 0.671 16
Random effect   χ 2 P χ 2 P χ 2 P  
    Field   0.577 0.4 11.5 <0.001 12.4 <0.001
  1. The level of significance is P < 0.05.