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Competency Area 4: Management of Arthropods

Introduction

Basic information about arthropods: 
Insects, mites and spiders are members of the group (Phylum) of organisms known as Arthropods (Jointed Legs). The other members of the Plylum (group) are listed in the table above. The Class of Insecta is separated from the Class of Arachnida (mites, spiders) by the number of body parts, number of legs and the presence/lack of antenna. Examples are shown below of the different orders of Arachnida. Agricultural important groups of Arachnida are the mites (plant feeding and beneficial) and spiders (beneficial).
In contrast, members of Class Insecta all have one pair of antennae, three body parts (head, thorax, abdomen), three pair of legs, adults usually have wings and breathing takes place using trachea.

Insect development:
is divided into two life cycle groups. In the Incomplete lifecycle group, the stages are egg, nymph and adult. In this group, the nymph looks very similar to the adult, however smaller and without wings. In addition, the feeding methods are often identical to the adults. In the complete life cycle group, the stages are egg, larvae, pupa and adult. In this group, the larva appears distinctly different than the adult life stage

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Insect Feeding is also divided into two distinct types and entire groups of related insects (Orders) have similar mouth parts. The two feeding types are 1) Chewing mouth parts and 2) Piercing and sucking mouth parts.
Chewing mouth parts remove solid tissue from the host and the tissue is ingested and utilized. A series of examples are shown below.
Piercing and sucking mouth parts remove fluid from the host in modified mouth parts which operate like a hollow needle. Often saliva is injected prior to feeding to breakdown cell walls and to start the digestion process before the fluid is ingested by the insect. The saliva left behind is frequently the cause of the feeding symptoms from the insect.