Feeding Strategies

Many different plant parts serve as sites of insect feeding activity. In general terms, borers can be distinguished from miners. Typically, larvae of miners feed within plant foliage, whereas larval borers may feed within other plant tissues, including roots, stems and twigs, meristems, fruit, conductive tissues, galls, and bark. The variety of plant tissues that are used by borers also spans an array of plant groups that range from the ferns and gymnosperms to the grasses and dicotyledonous angiosperms.

All plant tissues may be subject to borer colonization. Larvae of a number of families (e.g., Cerambycidae and Hepialidae) may construct feeding tunnels, or galleries, within the large roots of broadleaf trees and conifers, which may weaken the trees directly or provide entry points for invasion by pathogenic fungi. At the other extreme, there are many species of insects that colonize the meristematic tissues at branch terminals, tips, twigs, and canes. Some of these insects feed in the phloem tissues girdling the twigs, whereas

FIGURE 1 Adult pairs of the European elm bark beetle S. multistriatus excavate parental galleries in the cambium and phloem of host elm trees. Larvae eclose from eggs laid in niches cut into the margins of the parental galleries and construct feeding galleries that extend laterally into the same host tissues.

FIGURE 1 Adult pairs of the European elm bark beetle S. multistriatus excavate parental galleries in the cambium and phloem of host elm trees. Larvae eclose from eggs laid in niches cut into the margins of the parental galleries and construct feeding galleries that extend laterally into the same host tissues.

larvae of other species burrow through the growing tips and into the elongating stems. These types of larval feeding can reduce plant growth, apical dominance, and plant form.

Between the twigs or apical tips and the roots is the main stem or trunk of the tree. The woody xylem tissues, cambial layers, phloem tissues, and bark may all have different groups of specialist borers. For example, larvae of a few species of clearwing moths feed within the bark of their host plant. Scribble-barked gums are species of Eucalyptus in Australia that derive their common name from the twisting galleries constructed in the outer bark by lepidopteran larvae. In different feeding strategies, bark beetle larvae feed within the cambial and phloem tissues of their hosts (Fig. 1), whereas larvae of many species of longhorned and flatheaded borers feed in the outer layers of phloem and cambium but then bore deep into the wood to pupate. Alternatively, many other cerambycid and buprestid species feed almost entirely within the wood of their host trees. Larvae of cossid moths also feed entirely within woody tissues and may take several years to complete their larval development. Woody plant tissues are not as rich in nutrients as the cambial tissues and the quality deteriorates as the tissues age. Consequently, many wood borers may have prolonged larval development and long generation times.

Not only the larvae bore into woody tissues but also the adults in a number of species within a variety of families (e.g., some species of Scolytidae and Platypodidae) bore into the plant. The larvae of ambrosia beetles are found in galleries excavated within the wood, but they feed on a fungus inoc ulated into the tissue by the parental adults rather than on the plant itself. The fungi acquire nutrients from a large volume of plant tissue as the hyphae ramify throughout the wood.

Bee Keeping

Bee Keeping

Make money with honey How to be a Beekeeper. Beekeeping can be a fascinating hobby or you can turn it into a lucrative business. The choice is yours. You need to know some basics to help you get started. The equipment needed to be a beekeeper. Where can you find the equipment you need? The best location for the hives. You can't just put bees in any spot. What needs to be considered when picking the location for your bees?

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