The chemical cues used by Coccinella septempunctata are fairly well documented. There are several compounds that are used throughout its life and for a variety of behaviors. This species overwinters in aggregations within dense foliage, and implements chemical cues to attract other individuals. This specific pheromone for Coccinella septempunctata was isolated and identified to be 2-isopropyl-3-methoxy-pyrazine. This cue not only attracts individuals to a relatively safe overwintering aggregation, but also ensures that the group will exit diapause with a local population to mate with. Several chemical cues are also used in finding prey, particularly aphids. For instance, the alarm pheromone that aphids release from their cornicles when a predator is sensed (used as a warning between aphids) is an attractant to C. septempunctata. Cues released by plants in response to aphid herbivory are also utilized by coccinellids to locate aphid infested plants.
Intraguild predation during the larval stage is high in this family of predaceous insects as an adaptation due to the short-lived nature of aphid colonies and the limited distances that larvae can travel to locate food. Due to this high evolutionary pressure, Coccinella septempunctata is deterred by the compounds associated with hetero- and conspecific eggs, which decreases the likelihood of offspring mortality due to cannibalism and predation.
Communication Channels: visual ; chemical
Other Communication Modes: pheromones
Perception Channels: visual ; chemical
Coccinella septempunctata is considered an invasive species and is not on any conservation lists, globally, nationally, or within any state.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
After emergence from the egg, a larva will remain with its egg casing, eat it, and eat any infertile eggs in the vicinity. As the instars develop, they shift from sucking aphid liquids as meals to eating the entire insect. Coccinella septempunctata has four instars, the lengths of which are largely influenced by the abundance of aphids and temperature. Before pupation, the fourth instar will stop foraging for 24 hours and attach itself to a substrate with the tip of its abdomen. After emergence from the pupal casing, Coccinella septempunctata has very soft elytra that lack pigmentation. The characteristic coloration develops with time. The red and black pigments of the elytra are derived from melanins, while the lighter areas develop from carotenes.
Development - Life Cycle: metamorphosis ; diapause
Many native coccinellid species are being driven away by Coccinella septempunctata; unrealized human benefits from these native species could therefore be lost as Coccinella septempunctata continues to dominate more and more ecosystems. Emerging dominance of this species outside of agricultural landscapes could detriment overall ecosystem health. Any retrospective restoration efforts could be costly to humans. Coccinella septempunctata is also a nuisance to the wine industry, as it is sometimes accidentally caught on crops and incorporated during the wine making process. Chemicals produced by C. septempunctata taint the taste and quality of wine.
Coccinella septempunctata is a common species used for biological control in agriculture settings, as its main prey is the aphid, a major agricultural pest. Aphids are small Hemipterans that eat the phloem from a diverse set of plants and can have devastating effects on crop yields. Aphids also harm plants by indirectly transferring diseases and fungi. C. septempunctata is one of the most successful aphidophagous insects and has been employed across the U.S. to control aphid populations. The ability of C. septempunctata to be so successful in a large range of habitats makes it especially beneficial to humans who need crop security from aphid infestations.
Positive Impacts: controls pest population
Coccinella septempunctata are voracious predators of plant harming aphids and scale insects. The ability of this species to depress the populations of these insects is valuable in an ecosystem and helps control the destruction of plants that are important for other organisms. C. septempunctata is prey to many bird, small mammal, and spider species, as well as other Coccinellidae.
Coccinella septempunctata serves as host to a large variety of parasites and parasitoids. Parasitic wasps of the families Eulophidae and Braconidae, and flies of the family Phoridae parasitize the larvae of C. septempunctata. The braconid wasps Perilitus coccinellae and Dinocampus coccinellae are the most well known species that are parasitoids of Coccinella septempunctata. P. coccinellae develops in sync with the larvae and/or adult of the ladybird beetle and will even remain at the diapause induced state until the host comes out of diapause. D. coccinellae eggs are typically deposited within the body cavity of a female of Coccinella septempunctata and proceed to hatch and eat the eggs of the female. The host is unaffected by the further progress of this wasp larva until it pupates within a leg of the host and emerges as an adult up to 9 days later; some adults are apparently able to revive from this emergence event and continue their life cycle.
Commensal/Parasitic Species:
Coccinella septempunctata is a polyphagous species; it mainly preys on aphids and other similar scale insects, but when such resources are low, adults will eat pollen. Some adults will even eat conspecific eggs or larvae if the situation calls for it. Larvae are predators of aphids generally, but will eat other Coccinellidae larvae if aphids are absent. Intraguild predation and cannibalism are major pressures in this species and family.
Animal Foods: insects
Plant Foods: pollen
Primary Diet: carnivore (Insectivore )
Coccinella septempunctata originated in Europe and Asia, but is now found throughout the Middle East, India and North America (U.S. and Canada). Several intentional introductions of C. septempunctata occurred between 1951 to 1971 in the U.S. for biological control of crop threatening aphids. None of these releases were thought to be successful in creating a natural population until 1973 when an established population was found in Hackensack Meadowland, New Jersey. However, this population was thought to have arisen from an accidental release. Populations continued to arise in the eastern U.S. and Canada, either purposefully or unintentionally in the following years. Since then, this species has become one of the most common and widespread coccinellid species in the Nearctic range.
Biogeographic Regions: nearctic (Introduced ); palearctic (Native ); oriental (Native )
Coccinella septempunctata can be found wherever significant numbers of prey, particularly aphids, are present. This normally includes small herbaceous plants, shrubs and trees in open fields, grasslands, marshes, agricultural fields, suburban gardens and parks. The preferred overwintering habitat for Coccinella septempunctata is an open area with sheltering boulders, small tussocks, or hedgerows of densely packaged grasses that are south-facing, maximizing sunlight hours.
Range elevation: sea level to 1500 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; forest ; scrub forest ; mountains
Wetlands: marsh
Other Habitat Features: suburban ; agricultural
An adult Coccinella septempunctata lifespan is generally between 1 to 2 years, depending on its survival through the winter.
Typical lifespan
Status: wild: 1 to 2 years.
Coccinella septempunctata looks like the quintessential ladybug: it is medium sized, has orangish-red elytra and black spots. It can be identified however, by several distinct characteristics. This species typically has seven black spots on its elytra (although it can range from 0 to 9). There is one spot next to the scutellum that bridges the junction between the two elytra; there are two white patches on either side of the scutellum, just above this black scutellar spot. The three spots on each elytra are variable in placement, but are generally rather bold. This species also has two characteristic pale white spots along the anterior side of the pronotum. The ventral side of the abdomen is convex and is almost exclusively black; males have slight hairs on the last abdominal segment.
The eggs of Coccinella septempunctata are small (1mm long) and oval-shaped.
The larval instars of C. septempunctata can be variable in color depending on temperature but are generally dark and highly segmented. Size increases with each consecutive molting.
The pupa is slate grey to black, sometimes having white or orange markings on the outside. It has a hardened exoskeleton which develops from the fourth instar. Its size is approximately the size of the adult Coccinella septempunctata.
Range length: 6.50 to 7.8 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous
Sexual Dimorphism: sexes alike
Coccinella septempunctata and other coccinellids have very few natural enemies in their adult stages. The typical bright colors of coccinellids, with high contrasting orange and black spots, functions as aposematic warning coloration. The visual cue of toxicity seen in coccinellids is successful in deterring most predators, but chemical signals are also a major defense component. Coccinella septempunctata has several toxic N-oxides and alkaloids that exude from the gland between the femora and tibia. These chemicals can be released due to threats or attacks from predators and can account for up to 20% of the body weight of the beetle. These compounds are highly toxic to many common beetle predators like birds and small mammals. Spiders are also known to prey on Coccinella septempunctata larvae. Intraguild predation and cannibalism on eggs and larvae are also significant threats. The fourth larval instar is the most vulnerable instar to predation, with a significant number of individuals perishing during this stage, though the explanation for this trend has yet to be explained in a controlled study.
Known Predators:
Anti-predator Adaptations: aposematic
Coccinella septempunctata reproduces sexually, with each male and female copulating with multiple partners in a breeding season. Males court females with a five step display: approach, watch, examine, mount and copulatory attempt. During the approach stage, a male will come within 1 cm of a desired female and watch her without making contact. The male will then examine the female by feeling her antennae and mouth with his own (examine). If suitable and accepting, the male will mount the female by climbing onto the elytra from behind and attempt copulation.
A sexually immature female will resist courtship from a male, along with females that have recently mated or are about to lay eggs. In one day, an individual might mate 4 to 6 times. Each female will mate with many males over the course of her lifespan. The multiple matings of females greatly increases fecundity, viability of eggs, and percent of successful hatchings. Females of Coccinella septempunctata are known to eject spermatophores, but do not eat them. There are no data suggesting the reason for spermatophore ejection in this species.
Unmated males and virgin females show the longest and most vigorous copulation, both of which decrease as an individual continues to accrue mating partners. Less vigorous mating is also prominent in males that copulate multiple times during one day, apparently due to exhaustion from exertion during previous copulations.
Mating System: polygynandrous (promiscuous)
Once a female has fertilized eggs she will begin to disperse them around her environment. A female might lay anywhere from 250 to 500 eggs in her lifespan. Coccinella septempunctata females are deterred by some olfactory cues of conspecific eggs in an area, and will lay eggs in areas without other eggs of the same species. Each suitable substrate will receive a maximum of 15 eggs. It is hypothesized that this trait allows females to have higher egg dispersal rates and also decreases intraspecific competition of larvae. There is a tendency in this species to produce more eggs than the carrying capacity of the environment, which places many offspring at high risk of mortality; however, occasional high abundances of aphids might make this reproductive strategy beneficial. Some males will fertilize females shortly before diapause, which causes some females to overwinter with sperm stored in their spermathecae.
Breeding interval: Coccinella septempunctata will breed from the point of sexual maturation (10 to 14 day after emergence) until dormancy.
Breeding season: The main breeding season of this species is spring and early summer, though a portion of the population continues into autumn.
Range eggs per season: 200 to 1000.
Average eggs per season: 440.
Range age at sexual or reproductive maturity (female): 10.8 to 11.6 days.
Average age at sexual or reproductive maturity (female): 11.4 days.
Range age at sexual or reproductive maturity (male): 8.5 to 9.3 days.
Average age at sexual or reproductive maturity (male): 8.8 days.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous ; sperm-storing ; delayed fertilization
Like all coccinellids, Coccinella septempunctata lacks any parental care. Males merely copulate with a female, while females do not influence development of offspring beyond providing nutrients in the eggs and depositing eggs on safe and resource rich substrates.
Parental Investment: pre-hatching/birth (Provisioning: Female)
