Acquired resources are allocated to various pathways. First, they either are assimilated or egested. Assimilated resources either are allocated to production or are expended (i.e., through respiration). Consumption and allocation of resources are influenced by insect size, maturity, food quality, and parasitism. Fitness accrues to the extent that assimilated resources are used for growth and reproduction. However, insect allocation patterns represent tradeoffs among competing requirements of growth, reproduction, and activities necessary for food acquisition, mating, reproduction, and interactions with other organisms.
Species persist to the extent that the benefits of these behaviors outweigh the costs (i.e., survival and reproduction are increased by the investment of energy in particular behavior and associated biochemicals). Foraging and reproductive behaviors should provide the best return for the time and effort spent searching. Reproductive behavior should maximize survival of offspring. Among insects, selection of appropriate oviposition sites determines egg development and survival. Brood care is well-represented among insects, with examples ranging from protection of young, to provision of food resources, to development of complex social systems for brood care and colony maintenance. However, efficiency of adult behaviors may be in conflict with efficiency of juvenile behaviors. For example, adults may oviposit on the most easily found hosts, whereas survival of immatures may depend on discovery of more suitable food hosts.
Competition and defense against predators often involve considerable expenditure of resources. In many species, males engage in various forms of combat to decide which males mate successfully. Territorial behavior is characterized by both the marking of territorial boundaries and the defense of the territory against intruders. Defense of territories may maximize access to food or mates at low population densities but becomes less advantageous and may be abandoned at high population densities. Insects defend themselves against predators physically and chemically. Behavior often enhances the effectiveness of protective coloration or toxins. For example, cryptically colored insects usually avoid movement during times when predators are active, whereas other insects may suddenly expose eyespots or brightly colored body parts to startle an attacker. Some insects imitate snakes or other predators through color patterns or movements. Such strategies minimize the energetic cost of physical defense but require greater efficiency in foraging or reproductive movements to avoid detection.
The efficiency of foraging, reproductive, competitive, and defensive behavior may be increased by use of visual, chemical, or acoustic signals that communicate information to recipients. Insects can improve foraging and mating efficiency by orienting toward chemical cues produced by suitable resources or potential mates. Discovery of a potential mate initiates a courtship ritual that improves fitness by ensuring species recognition and receptivity. Competition for food or mates can be minimized by signals that deter other individuals.
Environmental changes will affect the efficiency of resource acquisition and allocation strategies. For example, global warming will improve energy balance for some species (e.g., early season or high latitude pollinators) but increase respiration costs beyond ability to acquire energy and nutrients for others. Ultimately, insect strategies for acquiring and allocating energy and nutrient resources affect community interactions, energy flow, and nutrient cycling processes.
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