Many commercially important legume, fruit, vegetable, and nut crops require crosspollination to set seed. Such plants utilize the services of various agents, among them insects, to transfer pollen from anthers to stigmas. The 'reward' that insect pollinators receive for this service is food, particularly nectar and pollen. This reward is often 'advertised' through floral markers (or cues) such as colour, odour, and form. Despite such markers and rewards, the food crop that requires pollination (i.e. target crop) is often less attractive, or rewarding, than other plants flowering in the same area. For this reason, insect pollinators frequently desert the target crop when pollination is urgently required, and there is a consequent loss in yield.