Insect Plant Mutualism

Not all insect-plant relationships are of the "constant warfare" type just discussed. For a large number of insect and plant species, an interaction of mutual benefit has evolved. Thus, some insects live in close association with plants, protecting them in return for food. For example, the bull's-horn acacias (Acacia spp.) are host to colonies of ants (Pseudomyrmex spp.) that live within the swollen, hollow stipular thorns and feed on nectar (produced in petioles) and protein (in Beltian bodies at the tips of new leaves) (Figure 23.3). In return, the aggressive ants guard the plants against herbivores and suppress the growth of nearby, potentially competitive plants by chewing their growing tips (Holldobler and Wilson, 1990).

A mutualistic relationship of a very different kind is that in which the host supplies food to insects, in return for which the insects provide the transport system for dispersal of pollen, seeds, and spores. Though their importance as pollinators for higher plants has been extensively studied (Kevan and Baker, 1983, 1999; Schoonhoven et al., 1998), it must be emphasized that some insects are essential for spore dispersal in some mosses and many fungi (see Chapter 16, Section 4.2.4), as well as transporting seeds of angiosperms. The success (importance) of insects as pollinators compared with pollinators from other groups such as birds and bats is presumably a result of their much longer evolutionary association

FIGURE 23.3. Mutualism between bull's-horn acacia and ants. (A) Acacia leaf and twig showing extrafloral nectary, hollow thorns, and leaflets with Beltian bodies at tips; (B) enlarged view of hollow thorn with entrance hole of ant nest; and (C) close-up view of Beltian bodies and ant visitor. [A, redrawn from W. M. Wheeler, 1910, Ants. Their Structure, Development and Behaviour. Columbia University Press. B, C, photographs courtesy of Dan L. Perlman.]

FIGURE 23.3. Mutualism between bull's-horn acacia and ants. (A) Acacia leaf and twig showing extrafloral nectary, hollow thorns, and leaflets with Beltian bodies at tips; (B) enlarged view of hollow thorn with entrance hole of ant nest; and (C) close-up view of Beltian bodies and ant visitor. [A, redrawn from W. M. Wheeler, 1910, Ants. Their Structure, Development and Behaviour. Columbia University Press. B, C, photographs courtesy of Dan L. Perlman.]

with plants. Most of the modern insect orders were well established by the time the earliest flowering plants appeared about 225 million years ago. Thus, insects were able to gain a considerable head start as pollinators over birds and bats, the earliest fossil records for which date back about 150 and 60 million years, respectively (Price, 1997).

To achieve effective cross-pollination, two important factors must be taken into consideration in an evolutionary sense. First, plants must produce precisely the right amount of

FIGURE 23.3. (Continued)

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.

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