Harmonia axyridis is oval shaped. It has three main color forms: red or orange with zero to many black spots (form succinea), or black with either four orange spots (form spectabilis) or two (form conspicua). Several less common forms exist as well. Darker forms are more common in its native range, with red or orange morphs more common in Europe and North America. The area behind the head is usually white with four black spots that form an "M" shape. The last segment on the body is different between males and females.
The eggs of H. axyridis are approximately 1.2 mm in length and yellow in color. Just before hatching, eggs darken to a gray or black color.
The larvae of H. axyridis have long bodies and are black with orange coloration (including two long orange lines on the middle of their backs, which start to develop after the first larval stage, and are complete by the last larval stage). They have spines along the length of the body. Larvae are longer in length than adults, growing as long as 7.5 to 10.7 mm in the later larval stages. Larvae look like tiny black and orange alligators.
Pupae are exposed and generally shaped like a long dome, often attached to leaves. They are usually orange, with the exoskeleton from the fourth larval stage still attached at the point of attachment. (Arnett, 1993; Banks, 1957; Gordon, 1985; Hagan, 1962; Hodek, 1996; Sasaji, 1971)
Harmonia axyridis, the Asian lady beetle, is originally from the Oriental region, found in China, ranging to the far south (Yunnan and Guangxi Provinces), Japan, Korea, Mongolia, and parts of the Palearctic region, from northern Kazakhstan, and eastern Russia west to the Altai Mountains and north to Siberia. It has been introduced to at least four other continents. Its range covers most of North America; it is found in Mexico, across the United States (excluding Alaska and Wyoming) and much of southern Canada. This species has been found across South America, excluding areas near the Amazon river. Its habitat ranges across southern and western Europe into Bosnia and Herzegovina and Romania, and recently was found in Tunisia, Egypt, and South Africa. (Brown, et al., 2011; Osawa, 2000)
Harmonia axyridis can be found on many crop species on farm lands where it has been introduced. It is often found on deciduous trees, flowering plants, and other plant species found in open areas. This species tends to live in open fields, agricultural fields, and meadows. (Borror and White, 1970; Brown, et al., 2011; Hagan, 1962; Hodek, 1996; Koch, 2003)
Harmonia axyridis is holometabolous, meaning it goes through complete metamorphosis. It develops from an egg through four larval stages (instars), to pupa and then adult. The diet of the beetle is known to have an effect on larval development and adult weight, as is temperature. Harmonia axyridis usually has two generations per season in much of the world, although up to four or five generations per year have been observed. Adults go into hiding over winter and start laying eggs in early spring, whenever average temperatures begin to reach 12°C. (El-Sebaey and El-Gantiry, 1999; Kindlmann, et al., 2000; Koch, 2003; LaMana and Miller, 1998; Osawa, 2000)
Harmonia axyridis produces pheromones to attract mates, and at close distances may use sight to identify mates. Reproduction is sexual, with internal fertilization. Many females are picky when choosing male mates. Some decide on their mates based on the color of the male elytra (which cover the wings). This may have to do with the fact that certain colors provide better camouflage from predators. By choosing males of certain colors to mate with, offspring will have better camouflage and will be more likely to survive. H. axyridis is usually polygynandrous, meaning that these beetles mate many times with many different beetles. After mating, males do not do anything to defend the female from other males. (Hodek and Ceryngier, 2000; Koch, 2003; Stathas, et al., 2001)
Females of Harmonia axyridis will produce many eggs per season, laying about of 25 eggs per day. Females tend to lay egg clusters, with numbers ranging between 20 and 30 eggs per group. This species will breed many times during its lifetime. Females may lay unfertilized eggs that will not hatch along with the fertilized eggs. When larvae hatch, they eat the unfertilized eggs, which is useful in case other food is not available. (El-Sebaey and El-Gantiry, 1999; Hodek, 1996; Koch, 2003; LaMana and Miller, 1998; Perry and Roitberg, 2005)
Females provide nutrients in the eggs for the offspring to use to grow and develop. Also, females may lay unfertilized eggs that will never hatch along with the fertilized eggs. Larvae can eat the unfertilized eggs after they hatch. Otherwise, H. axyridis does not provide any parental care. (Koch, 2003; Osawa, 1993; Stathas, et al., 2001)
In its native range, Harmonia axyridis has two generations per year, but it has five generations in some places. Adults usually live 30 to 90 days, although some have lived over 3 years. (El-Sebaey and El-Gantiry, 1999; Koch, 2003; LaMana and Miller, 1998)
Harmonia axyridis lives alone, but it will gather in large groups to hibernate over winter. Studies show that for many lady beetle species, they will go into hibernation once daylight hours decrease to between 10 and 13 hours a day, since days get shorter as winter approaches. H. axyridis is an active predator, often flying from plant to plant to find prey species. It moves around mostly during the day. (Banks, 1957; Biddinger, et al., 2009; Colunga-Garcia, et al., 1997; Hagan, 1962; Osawa, 2000)
Harmonia axyridis does not generally do anything to defend its home from other lady beetles. Instead, it moves freely through its habitat. (Banks, 1957; Colunga-Garcia, et al., 1997; Hagan, 1962; Osawa, 2000; Banks, 1957; Colunga-Garcia, et al., 1997; Hagan, 1962; Osawa, 2000)
Like many insects, Harmonia axyridis communicates with chemicals and pheromones. Many pheromones are used to find and communicate with mates. They also use these pheromones to find other lady beetles to spend the winter together. One pheromone that Harmonia axyridis uses is called harmonine. It is used for protection against predators. When H. axyridis is in danger, it produces harmonine and releases it from the joints in its legs, an act called reflex bleeding. H. axyridis finds prey by using sight or smell. (Colunga-Garcia, et al., 1997; Evans, 2003)
Harmonia axyridis is an insectivore. It mainly eats aphids and scale insects. It sometimes also eats other insects in the order Thysanura, as well as the eggs of butterflies and moths. It will also eat mites. When these prey are not around, H. axyridis will eat other lady beetle species. It will also feed on grapes and other fruits, and very rarely eats pollen. Cannibalism also occurs in this species. Both adults and larvae of Harmonia axyridis will eat eggs and smaller larvae of its own species. (Adriano, et al., 2009; Alhmedi, et al., 2010; Berkvens, et al., 2010; Burgio, et al., 2002; Campbell and Cone, 1999; Davidson and Evans, 2010; Dixon, 2005; Evans, 2003; Naoya, 2011; Osawa, 2000; Pervez, 2006; Sloggett, 2008)
Many species of bird prey on Harmonia axyridis. Many other insect species also feed on H. axyridis. The pentatomid bug, Podisus maculiventris is known to prey on H. axyridis, as well as many species of ants, including the red imported fire ant, Solanopsis invicta. Other lady beetle species will prey on H. axyridis, although only when the other lady beetles are larger. Cannibalism on eggs and larvae is also very common in this species.
To defend itself, Harmonia axyridis produces isopropyl methoxy pyrazine (IPMP), which it secretes from its leg joints when threatened. This is a chemical defense, making it poisonous to predators. This species also has antimicrobial agents in its body that protect against bacteria and yeast. The red and black coloring of H. axyridis is called aposematic coloration. Predators know that insects with bright colors like these are usually poisonous, and do not attack them as often. The colors act as a warning signal to predators. (Firlej, et al., 2005; Gross, et al., 2010; Katsoyannos and Aliniazee, 1998; Koch, 2003; Nalepa and Weir, 2007; Nalepa, et al., 1996; Riddick, et al., 2009; Roy, et al., 2008; Saito and Bjørnson, 2008; Sloggett, et al., 2011)
Many parasites and parasitoids use the body of Harmonia axyridis to grow and develop in. These species include flies (Strongygaster triangulifer) and wasps (Dinocampus coccinellae, Oomyzus scaposus, Homalotylus terminalis, Pachyneuron altiscuta). Mites of the genus Coccipolipus, protozoans (such as Microsporidia), nematodes, and fungal species (Hesperomyces virescens, Beauveria bassiana) may also use the body of H. axyridis as a host.
In areas where it is not originally from, Harmonia axyridis competes with native lady beetle species for resources. H. axyridis usually out-competes these other species by using resources more efficiently, causing decreases in the population sizes of these other lady beetles. Some of the lady beetle species most affected are Coccinella transversoguttata, Adalia bipunctata, and Coccinella novemnotata. H. axyridis also preys on insects that eat crops and other plants, which helps prevent plant damage. (Banks, 1957; Gordon, 1985; Kindlmann, et al., 2011; Lombaert, et al., 2010; Sloggett, 2008)
Since Harmonia axyridis will sometimes eat grapes and other fruits, it can cause significant economic damage on these crops. These lady beetles will crawl inside the grapes to feed, and when threatened by farmers or machinery collecting the grapes, they bleed toxic chemicals from the joints in their legs. These chemicals that are normally meant for predators cause a bad taste in the fruit. These chemicals can also be tasted in wine if H. axyridis has fed in the grapes used during the wine-making process. H. axyridis is also known to bite humans if handled. (Botezatu, et al., 2013; Galvan, et al., 2009)
Since Harmonia axyridis mainly eats aphids and other pest insects that can do serious damage to crops, it can control the populations of these pest insects. This prevents damage to crops. Since they are also intense predators, they are able to survive in many habitats, making them a very useful population control species. (Alhmedi, et al., 2010; Campbell and Cone, 1999; Davidson and Evans, 2010; Dixon, 2005; Gardiner and Landis, 2007; Sloggett, 2008)
Harmonia axyridis is not an endangered species.
Dylan Graves (author), University of Michigan Biological Station, Angela Miner (editor), Animal Diversity Web Staff, Brian Scholtens (editor), University of Michigan Biological Station.
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