A study of the insect’s environment Ecology A study of the insect’s environment

Organization of an Ecosystem Individual Population = all of one species in a study area Community = all of the populations in a study area Ecosystem = inclusion of the influence of both biotic and abiotic factors in a study area Biosphere = inclusion of all the ecosystems on the earth

The Aquatic Environment Properties of water as an influence Usually found in liquid state Gets heavier as it cools until maximum density at 4 deg C., result is that water freezes from the top down allowing depth and length of freezing weather to determine how much of the water solidifies. Water is capable of absorbing large amounts of heat (500 X that of air) but diffusion of heat is several thousand times slower than air.

This capacity creates a relatively stable and uniform situation compared to air Relationship to gases, the temperature of water determines the amount of oxygen that can remain dissolved, the warmer the water the less oxygen remain dissolved. Molecular cohesion of surface water when in contact with the atmosphere known as surface tension can be used by insects Uneven distribution of charges along the molecule give it a distinct polar characteristic which cause an arrangement that neutralizes electrical charges allowing water to act as a (universal solvent)

Water is dense and viscous

How do the characteristics affect Oxygen content Cold water < oxygen Oxygen level in day higher but drops at night when plants stop photosynthesis Greater the depth the more difficult to get oxygen to the bottom because of the slow diffusion Turbulent water adds atmospheric oxygen easier than still water

Salinity reduces the solubility of oxygen Effects Dead and decaying materials lowers oxygen levels because of bacterial respiration Salinity reduces the solubility of oxygen Effects Insects without low oxygen tolerance are restricted to cool turbulent waters and need adaptations such as gills to increase surface area for oxygen absorption. Most immatures have closed tracheal systems that won’t function in this environment

Gills allow the insect to be larger and survive in lower oxygen environments Some insects larvae breath atmospheric oxygen through a tube protruding through the surface tension of water (mosquito). Some insects carry oxygen in a bubble Few insects can survive salt water environments

Salts The more dissolved materials in the water the more difficult it is to maintain a balanced osmotic pressure. Hyperosmotic insects must extrude oxygen and ammonia. Hyposmotic insects must guard against water loss and extrude uric acid and/or use a dessication resistant coating/cuticle

Alkalinity and Acidity Acidity/Alkalinity is a description of the relationship of H+ ions vs OH- ions pH represents parts hydrogen pH of 7 represents little difference in the concentrations and as you lose a number the H+ ions increase 10 fold, conversely as you increase a number the OH- ions increase 10 fold so that a pH of 3 is very acidic and a pH of 13 is alkaline. The pH range is from 0 to 14

Sea water has a fairly stable pH of slightly more than 8 Fresh water generally varies from around a pH of 3.5 to 10.5 Affect: Some insects can have a wide range of tolerance such as the whirligig beetle that can tolerate acidity to as high as 3.5, but most often need specific a fairly specific pH to survive, example mayfly nymphs will be gone long before you reach a pH of 5.