Insects rely heavily on semiochemicals to get information from the environment.
Insects use pheromones for intraspecific communication. There are many types of pheromones: sex pheromones, aggregation pheromones, alarm pheromones, trail-following pheromones, etc.
Synthetic pheromones extensively in insect pest control for monitoring, population reduction (attracticides), and mating disruption.
Insects use kairomones for finding food: host plants, nectar, prey and host insects.
Mimicry and Camouflage
Batesian mimicry: a non-harmful species (mimic) has evolved to look like a harmful species (model)
Mullerian mimicry: two or more unrelated noxious, or dangerous, organisms exhibit closely similar warning coloration (usually patterns often yellow, red and black stripes)
Camouflage
Population dynamics
Exponential model
Logistic model
Carrying capacity (k): maximum population size that can be sustained by the environment
r-selected and k-selected species
Lotka-Voltera model for population dynamics of interacting species
Invasive species
An invasive species is alien and causes harm.
Invasive species readily establish on tropical islands because they have "escaped from natural enemies", weather is benign (no winter, high humidity), and there is usually plenty of food and water.
Fifty percent of Guam's invasive insects belong to Order Hemiptera.
Applied entomology
Pest control based solely on pesticide application is limited because of pesticide resistance and nontarget effects.
Integrated pest management (IPM): one or more pest control tactics are selected based on knowledge of the current situation gained from pest monitoring.
IPM tactics include pesticide application, sanitation, biological control, physical control, cultural control, and "do nothing".
Economic threshold level (EIL): the population density at which pest control should be initiated to prevent economic damage.
If possible, broad spectrum pesticides should be avoided because they may kill beneficial insects which will lead to an uncontrolled resurgence of pests.