Insects and Diseases

 Insects & relatives have a lightweight, but strong exoskeleton – chitin, like fingernails ◦ Allows burrowing, tunneling ◦ Protection from predation ◦ Reduces water loss ◦ Greater muscle force ◦ Cannot grow – must be shed: MOLTED

 During molting process, insect is vulnerable ◦ Often white – highly visible ◦ Soft, easily crushed ◦ Often hide, or molt at night ◦ Usually stop feeding  After molt, exoskeleton is flexible  Inhales to increase size, allow growth

 Insects can sense: ◦ Light ◦ Pressure ◦ Sound ◦ Temp ◦ Wind ◦ Odors

 Head ◦ Food and sensory intake  One pair of antennae  One pair of compound eyes  1 to 3 simple eyes ◦ Information processing  Brain ◦ Mouthparts – Key to ID of Damage; Control  Chewing  Sucking  Piercing

 Thorax (divided into 3 segments) ◦ Structural support for 6 legs (one pair of legs on each thoracic segment)  Running  Grasping  Digging  Swimming ◦ Structural support for wings  1 or 2 pairs  Wings may be absent  Abdomen (divided into 11 segments) ◦ Reproduction ◦ Digestion ◦ Circulation ◦ Respiration

 Internal systems are simple, yet functional  Circulatory ◦ Simple heart and aorta ◦ Blood flows freely within body cavity ◦ Not oxygen carrying, green blood  Respiratory ◦ Air enters through spiracles ◦ Branching tubes distribute oxygen ◦ Horticultural oils

 Digestive ◦ Long, tubelike gut ◦ divided into sections each with a different function ◦ BT bacteria damages the gut

 Nervous ◦ Transports and process info from sensory organs ◦ Brain in head; other nerve centers ◦ Phermone compounds confuse ◦ Nerve toxins

 Reproductive ◦ Most reproduction is sexual ◦ Males may be rare or seasonal ◦ Males may be absent (aphids) ◦ Some wasp species  males from unfert. eggs  females from fert. eggs  Ovipary(eggs), vivipary (live birth) both common