CLASS INSECTA

· Found in terrestrial and aquatic habitats

· Three patterns of development:

o Ametabolous – direct development

o Hemimetabous – nymphal stages

o Holometabolous – larval stages, followed by a pupal stage where there is complete rearrangement of tissues from imaginal disks

· Hormonal control of animal development
http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=dbio&part=A4302

· Exoskeleton provides framework for muscles, water conservation, armor, wings for flight.

· Dioecous

· Some species are social, with elaborate colonies

o Hymenoptera (bees and ants)

o Isoptera (Termites)

Types of Biological Transmission found in insects

1. Propagative biological transmission, in which the disease-causing organism reproduces in the arthropod, but undergoes no further developmental changes.

a. Plague bacillus in flea

b. yellow fever virus

2. Cyclopropagative biological transmission, in which the disease-producing organism undergoes cylical changes and reproduces in the arthropod.

a. Plasmodium in mosquitos

b. Trypanosoma in tsetse flies

3. Cyclodevelopmental biological transmission, in which the disease-producing organism must undergo development in the arthropod but does not multiply there.

a. Microfilarie in mosquitos

4. Transovarian transmission, in which disease-causing organisms are transmitted from the infected parent arthropod to their offspring.