No additional comments.
To locate prey, H. convergens uses primarily visual, olfactory, and chemical cues. Closely related species of coccinellids have been found to respond to aphid pheromones and other chemical cues. Honeydew secreted by aphid prey is also thought to be a significant chemical cue to coccinellids predators, and has even been shown to increase oviposition in H. convergens and other Coccinellidae. Larvae are also thought to respond to aphid chemical cues while searching for prey, though it is likely that prey search by larvae is more random than adults. Larvae rely heavily on tactile cues, and have been shown to follow along leaf veins until they either detect olfaction-based cues or just bump into aphid prey.
Communication Channels: visual ; tactile ; chemical
Perception Channels: visual ; tactile ; chemical
Hippodamia convergens has no special conservation status.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Hippodamia convergens goes through the same life cycle as other Coccinellids, progressing from the egg stage to the larval stage, then to pupation and finally adulthood. Eggs hatch after approximately a week, and then larvae develop through four instars over the course of two to three weeks. Convergent lady beetles are unique in that during food scarcity, they are able to alter their development in response. Individuals wait until they are between 5 to 35 mg (optimal weight being greater than 15 mg) to go through the process of pupation. It is common for a final instar larva to attach itself to the surface of leaves right before molting and forming a pupa. H. convergens generally has two generations a year, one in the spring and the other in the fall. During times of food scarcity or extreme temperatures, adults of H. convergens can enter diapause. The first generation of the year will often diapause at some point during the summer, while the second generation will diapause over winter.
Development - Life Cycle: metamorphosis ; diapause
Although Hippodamia convergens is helpful and often transported for agricultural purposes, this species can act as a transmitter for diseases and parasites. The trade and transportation of this lady beetle has increased the risk of introducing new pathogens into the United States.
Hippodamia convergens is of great economic benefit to humans. Convergent lady beetles are reared and sold as pest control agents for farms and gardens, since they are the natural predators of agricultural pests, particularly many species of aphids and scale insects.
Positive Impacts: controls pest population
Hippodamia convergens is a significant predator of many agricultural pests, particularly aphids. They also feed on a variety of other insects. Birds and generalist predatory insects such as Geocoris bullatus and Nabis alternatus feed on H. convergens. Pathogens such as Microsporidia use convergent lady beetles as hosts, which causes delayed larval development. These pathogens are often horizontally transmitted among this species, as H. convergens will cannibalize its eggs and larvae in times of low prey density. The braconid wasp Perilitus coccinellae is known to use H. convergens as a host. Parasitoid hymenopterans such as Dinocampus coccinellae have been found to also use convergent lady beetles as hosts, with females being infected at a higher rate than males. Parasites travel with their host lady beetles that are shipped for agricultural control purposes, which has likely caused an increase of parasites in the regions to which they are shipped.
Hippodamia convergens is predacious. It feeds on other insects and sometimes on small arthropods. Convergent lady beetles typically eat aphids, scale insects, and plant mites. Cotton, pea, melon, cabbage, potato, green peach, and corn leaf aphids are all prey that convergent lady beetles have been reported to eat. This makes this species a useful tool in controlling aphid populations on farms. Hippodamia convergens also eat the eggs and larvae of other insects, such as stinkbugs, asparagus beetles, and potato psyllids. Although both immature beetles and adults eat mostly aphids, during the fall when they are getting ready for hibernation, adults will feed on pollen to gain extra fat for hibernation. When there is food scarcity, it is not uncommon for coccinellids to become cannibalistic and eat their own larvae and eggs.
These beetles have a large appetite and may consume between 40 to 75 aphids per day. It has been shown that temperatures around 23 degrees Celsius cause these lady beetles to eat the most aphids. This indicates that the species is better at controlling aphid populations at this higher temperature.
Animal Foods: insects; terrestrial non-insect arthropods
Plant Foods: pollen
Primary Diet: carnivore (Insectivore )
Hippodamia convergens can be found in most of the Nearctic and Neotropical regions. It is a common species throughout the United States, ranging from New Jersey to Texas to California. It also common in Canada and South America.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Hippodamia convergens, the convergent lady beetle, is found in a diverse array of habitats including forests, grasslands, agricultural fields, and suburban gardens. Convergent lady beetles are found on crops in gardens and farms where there are plenty of aphids and other prey to eat. Typical crops on which they live are wheat, sorghum, and alfalfa. During the winter, H. convergens can be found under logs, ground-covering vegetation, and even in buildings.
Habitat Regions: terrestrial
Terrestrial Biomes: savanna or grassland ; forest
Other Habitat Features: suburban ; agricultural
It takes about 4 to 7 weeks for H. convergens to develop from egg to an adult. Adults live for an extended period after that, with the second generation overwintering.
Hippodamia convergens is semi-hemispherically shaped and has elytra that are yellow/red or tannish red with 12 black spots. The beetle does not have the typical oval shape of most lady beetles and the elytra are not as curvaceous. Hippodamia convergens has three separate spots on the posterior of the elytra, while their legs and underside are all black. These beetles have short legs with 3 segmented tarsi and short antennae as well. The prothorax is black with a white border and white lines that are directed inward towards one another and the abdomen; they are converging, thus giving this beetle its name. The prothorax does not align perfectly with the front edge of the elytra.
Eggs are typically 1 to 1.5 mm, elongated, and pointed at one end. Larvae look like alligators and are distinct because of the orange spots that they have on their prothorax. Pupae are orange and black and have a hemispherical shape.
Range length: 4 to 5 mm.
Range wingspan: 2.7 to 4.4 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry ; poisonous
Sexual Dimorphism: sexes alike
Generalist insect predators such as Geocoris bullatus and Nabis alternatus are known to eat eggs of H. convergens. Birds are often predators of H. convergens as well. In defense, the red and black coloration of the elytra of convergent lady beetles serves as warning coloration. Avian predators have been shown to recognize lady beetles with red color and black spots and eat them less frequently than lady beetles with no spots or different coloration. Additionally, like most coccinellids, H. convergens can likely bleed toxins from the joints in its exoskeleton.
Anti-predator Adaptations: aposematic
No information was found about the mating systems of these lady beetles specifically, but it is likely that they mate multiple times with multiple mates, as do other Coccinellidae.
Mating System: polygynandrous (promiscuous)
Hippodamia convergens is a bivoltine species, with two generations a year, one in the spring and the other in the fall. Females of H. convergens are able to enter into reproductive diapause during dry seasons or times of extreme temperature, when food resources are not plentiful enough for it to reproduce successfully. Egg laying generally coincides with aphid population cycles, with the most egg laying taking place when aphid populations are at their peak. Females have been shown to increase oviposition in the presence of aphids. A female can produce 200 to 500 eggs in her lifetime.
Breeding interval: H. convergens breeds continuously after reaching sexual maturity, while aphid numbers are high.
Breeding season: One generation mates in early spring, while the other generation mates in early fall.
Range eggs per season: 200 to 500.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); oviparous
No information was found about parental investment in this species, but it is likely that, as with other coccinellids, it provides only nutrients in the egg as parental investment.
Parental Investment: pre-hatching/birth (Provisioning: Female)