Effects on plant fitness Nectar robbing

pollination systems mutualistic, meaning plant benefits pollinator s transport of male gametes , pollinator benefits reward, such pollen or nectar. nectar robbers receive rewards without direct contact reproductive parts of flower, behaviour assumed cheating. however, effect of robbery on plant neutral or positive. example, proboscis of e. elvina not come in contact reproductive parts of flower in c. ovandensis, not lead significant reduction in fruit-set of plant. in example, when 80 percent of flowers in study site robbed , robbers did not pollinate, neither seed nor fruit set negatively affected.

the effect of floral-nectar robbing on plant fitness depends on several issues. firstly, nectar robbers such carpenter bees, bumble bees , birds can pollinate flowers. pollination may take place when body of robber contacts reproductive parts of plant while robs, or during pollen collection bees practice in concert nectar robbing. impact of trigona bees (e.g. trigona ferricauda) on plant negative, because aggressive territorial behaviour evicts legitimate pollinators. nectar robbers may change behaviour of legitimate pollinators in other ways, such reducing amount of nectar available. may force pollinators visit more flowers in nectar foraging. increased number of flowers visited , longer flight distances increase pollen flow , outcrossing, beneficial plant because lessens inbreeding depression. requires robber s not consuming of flower s nectar. when robber consumes of flower s nectar, legitimate pollinators may avoid flower, resulting in negative effect on plant fitness.

the response of different species of legitimate pollinators varies. species, bumble bees bombus appositus or b. occidentalis , many species of nectar-feeding birds can distinguish between robbed , unrobbed plants , minimize energy cost of foraging avoiding heavily robbed flowers. pollinating birds may better @ insects, because of higher sensory capability. ways bees distinguish between robbed , unrobbed flowers have not been studied, have been thought related damage on petal tissue after robbery or changes in nectar quality. xylocopa varipuncta steals nectar through slit make in base of petals. if nectar robbing severely reduces success of legitimate pollinators may able switch other nectar sources.

nectar robbing, birds, can damage reproductive parts of flower , diminish fitness of plant. in case, effect of robbery on plant direct. example of indirect effect change in behaviour of legitimate pollinator, either increases or decreases fitness of plant. there both primary , secondary nectar robbers. secondary robbers (e.g. flies , bees) take advantage of holes made primary robbers.

the effect of robbing positive if robber pollinates or increases pollination legitimate pollinator, , negative if robber damages reproductive parts of plant or reduces pollination success, either competing legitimate pollinator or lessening attractiveness of flower. distinguishing between legitimate pollinator , nectar robber can difficult.