Arguably the most pivotal trait of living organisms is their capacity to react to stimuli. This capability enables them to make responses that promote their survival and reproductive success in an ever-changing environment. The behaviour of animals like insects in evidently dependent on a highly intricate coordination of bodily functions, with the most crucial components being the nervous system, including sensory functions, and chemical control systems.
Communication
Insect communication relies on the transmission and reception to induce behavioural changes in one or more individuals. There are three fundamental methods of communication in insects:
Visual communication. Colour patterns and other makings on the wings of Lepidopterans (butterflies and moths) may function as visual signals during mating rituals. Some insects use bright colours, eyespots, and other distinctive patterns to scare away predators or to mimic the appearance of other unappetizing species. Glowworm beetles possess the ability to transform stored chemical energy into light, employing it as a means to convey mating information. Additionally, the sophisticated camouflage exhibited by certain insects can be interpreted as a form of communication.
Auditory communication. Numerous insects utilise sound as a means of communication, which is so high that the human ear cannot detect them. Insect sounds can either be naturally generated or produced intentionally. Specific methods include vibrating organs, as seen in male cicadas attracting mates, body part friction or stridulation, such as the advertisement songs made by male field crickets and grasshoppers, and substrate knocking with their heads, as observed in disturbed termites. The sound produced through these methods, when detected by the sensory nervous system of other insects, can covey information related to sexual attraction, alarm, or aggression.
Chemical communication. A commonly utilized form of communication among individual insects of the same species involved the release of pheromones and allomones. Insects use pheromones to communicate with other members of the species, signal alarms, mark trails, regulate castes, and attract potential mates.
Aggregation pheromones are used to communicate with members of the same species. Alarm pheromones are emitted by insects when they feel disturbed or threatened, prompting ants, for instance, to evacuate their nests and scatter across the ground. Trail pheromones are used by insects like maps, guiding them to food sources.
Allomones, alternatively known as warning signals, are emitted by insects to caution other species. Some allomones can have strong odours and, in some cases, may even case blindness in the targeted animal.
Behaviour
The behaviour of insects may be a combination of innate or intrinsic and learned behaviour patterns.
Innate Behaviour
Innate behaviour is a genetically hardwired or inherited response or set of responses for a given stimulus that’s exhibited by insects. Examples of this behaviour include flight and mating.
Reflexes – are common automatic or involuntary responses to stimuli. One example involves flies extending their mouthparts in response to their leg tarsi making contact with a sugar solution. Sensory receptors on the leg tarsi transmit a signal through nerves to the central nervous system, promoting a message that directs the extension of the mouthparts. This kind of reflex is common in insects.
Kineses – are also common, random or non-directional movements initiated by the stimulus. There are two types of kineses, orthokinesis and klinokinesis.
- Orthokinesis – the intensity of stimulus determines the rate of movement. For example, many insects move much faster (in a random direction) when placed under direct sunlight and slower in the dark.
- Klinokinesis – the intensity of stimulus determines the rate of turning. For example, lice will turn more frequently in warmer conditions, which prevents them from getting too far from their host.
Taxis – directed movement towards or away from the stimulus (e.g. light, gravity, temperature). There are many types of taxis, a few examples are:
- Phototaxis – a reaction to light that may be positive or negative, e.g. houseflies and moths show a positive response to light while mosquitoes exhibit a negative response.
- Thigmotaxis – response to contact of touch. Cockroaches and earwigs are thigmotactic insects that maintain tactile contact with a surface as they move along it – this brings about a tendency to squeeze in cracks and crevices,
Learned Behaviour
Learned behaviour involves adaptive and persistent changes in behaviour that occur as a result of experience. Since insects have a relatively simple nervous system, they have demonstrated their ability to “learn” in each of the following ways:
Habituation – is the act of learning to “ignore” stimuli that are unnecessary, irrelevant, or repetitive. Some adult flies are repelled by the smell of peppermint oil, however, if maggots were cultured in the presence of the oil, the adult flies would be attracted to it rather than repulsed.
Whether insects are capable of reasoning is arguable, and it always will be. Reasoning involves solving problems through deduction based on information gathered from various experiences. Many contend that the capability to utilise tools is indicative of reasoning ability. For instance, in certain ant species that live in tropical trees, the larvae exhibit the capacity to generate silk. While grasping leaves, adult ants engage in a unique process where they use the silk produced by the larvae to literally sew the leaves together, each adult holding the larva in the process. The topic of whether insects are intelligent and capable of reasoning will always be up for debate.