The Biotic Environment

FIGURE 23.3. (Continued)

nectar to make an insect's visit energetically worthwhile, yet stimulate visits to other plants, and second, plants of the same species must be easily recognized by an insect. If too much energy is made available by each plant, then insects need visit fewer plants and the extent of cross-pollination is reduced. If a plant produces too little food (to ensure that an insect will visit many plants), there is a risk that the insect will seek more accessible sources of food, Natural selection determines the precise amount of energy that each plant must offer to an insect, and this amount depends on a number of factors. The amount of energy gained by an insect during each visit to a flower is related to both quantity and quality of available food. Thus, until recently, it was considered that many adult insects obtained their carbohydrate requirements from nectar and their protein requirements from other sources such as pollen, vegetative parts of the plant (as a result of larval feeding), or other animals. Baker and Baker (1973) showed, however, that the nectar of many plants contains significant amounts of amino acids, so that insects can concentrate their efforts on nectar collection. This not only increases the extent of cross-pollination by inducing more visits to flowers, but may also lead to economy in pollen production, as pollen becomes less important as food for the insects. The amount of nectar produced is a function of the number of flowers per plant. Hence, for plants with a number of flowers blooming synchronously, it is important that each flower produces only a small amount of nectar and pollen, so that an insect must visit other plants to satisfy its requirements.

More nectar is produced by plant species whose members typically grow some distance apart, so that it is still energetically worthwhile for an insect species to concentrate on these plants. Related to this, insects that forage over greater distances are larger species such as bees, moths, and butterflies whose energy requirements are high. When nectar is produced in large amounts, it is typically accessible only to larger insects that are strong enough to gain entry into the nectar-producing area or have sufficiently elongate mouthparts. This ensures that nectar is not wasted on smaller insects lacking the ability to carry pollen to other members of the plant species.

Temperature also affects the amount of nectar produced, as it is related to the energy expended by insects in flight and to the time of day and/or season. For example, in temperate regions and/or at high altitudes, flowers that bloom early in the day or at night, or early

Beekeeping for Beginners

Beekeeping for Beginners

The information in this book is useful to anyone wanting to start beekeeping as a hobby or a business. It was written for beginners. Those who have never looked into beekeeping, may not understand the meaning of the terminology used by people in the industry. We have tried to overcome the problem by giving explanations. We want you to be able to use this book as a guide in to beekeeping.

Get My Free Ebook


Post a comment