Pollinator exclusion experiments are experiments used by ecologists

Ecology

Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...

 to determine the effectiveness of putative plant pollination

Pollination

Pollination is the process by which pollen is transferred in plants, thereby enabling fertilisation and sexual reproduction. Pollen grains transport the male gametes to where the female gamete are contained within the carpel; in gymnosperms the pollen is directly applied to the ovule itself...

 vectors. Essentially, certain pollinators are prevented from visiting certain flowers, and observations are then made on the which flowers develop seeds. If the exclusion of a certain class of visitor prevents or greatly reduces flower fertilisation rates, then it can be concluded that that class of visitor plays an important role in pollination.

There are various methods for excluding pollinators. A cage may exclude nectarivorous birds and mammals but allow access by insects. A net may exclude all but the smallest animals, yet permit wind-pollination. Insect repellent

Insect repellent

An insect repellent is a substance applied to skin, clothing, or other surfaces which discourages insects from landing or climbing on that surface. There are also insect repellent products available based on sound production, particularly ultrasound...

 may prevent visits by insects whilst allowing access by birds and mammals. Bags may be used to prevent all but autogamous pollination. Bagging flowers only during the day or night makes it possible to exclude diurnal or nocturnal visitors respectively.