Subphylum Hexapoda Part 2: Life Cycle and Behavior

This tutorial details the life cycle and behavior of insects, including reproduction, metamorphosis, defense mechanisms, communication, and social behavior. It highlights the diverse relationships insects have with humans, ranging from harmful pests to beneficial pollinators and biocontrol agents, emphasizing the significant ecological and economic impact of insects on human society.

Insect Reproduction

• 00:00:18 While parthenogenesis exists in some species, internal sexual reproduction is more common. Insects utilize various methods to attract mates, including pheromones, light, and sound. Most insects are oviparous, laying eggs, but some are viviparous, giving birth to live young. Eggs are often laid near substrates that support developing young, sometimes even within other organisms, including other parasitic wasps.

Insect Metamorphosis

• 00:02:23 Insects undergo one of three types of metamorphosis: ametabolous, hemimetabolous, or holometabolous. Ametabolous, or direct development, features young similar to adults, while hemimetabolous, or incomplete metamorphosis, involves nymphs developing into adults. The most common type, holometabolous, or complete metamorphosis, involves distinct larval and pupal stages before adult emergence, with the insect's body often liquifying within the pupa.

Insect Defense and Communication

• 00:03:57 Insects employ various defense mechanisms, such as exoskeletons, repulsive odors and sprays, and stingers. They communicate using chemical, visual, auditory, and tactile cues, with pheromones as a common chemical signal. Some insects produce sounds for courtship and defense, while others use flight patterns, colors, or bioluminescence for visual communication. Tactile communication, like antennae touching, plays a role in behaviors such as locust swarming.

Insect Sociality

• 00:05:38 Insect sociality ranges from solitary to eusocial. Some insects form temporary or loosely connected groups, while others, like honeybees, ants, and termites, exhibit eusociality with complex social structures. Eusocial colonies rely on chemical and tactile communication and demonstrate polymorphism, with different castes like queens, workers, and drones. Some eusocial colonies are remarkably large, such as the Argentine Ant Supercolony or the Ishikari Supercolony.

Insect-Human Relationships

• 00:08:21 Insects have diverse relationships with humans, ranging from harmful pests that damage crops and carry diseases to beneficial pollinators, silk producers, and biocontrol agents. Human efforts to control pest insects with poisons and insecticides often have unintended consequences, like harming beneficial insects or leading to pest resistance. The loss of pollinating insects, like bees, due to pesticides and other factors would have significant ecological and economic impacts.