Coccinella septempunctata, the seven-spot ladybird, is a widespread species originally native from Europe, Asia and Northern Africa. Because of its potential as a biological control agent of crop insect pests,...
Coccinella septempunctata (seven-spot ladybird); aggregation of adults in a conifer (Pinus spp.). Saltoun Forest, East Lothian, Scotlan, UK. October 2010.
Coccinella septempunctata (seven-spot ladybird); aggregation of adults in a conifer (Pinus spp.). Saltoun Forest, East Lothian, Scotlan, UK. October 2010.
Coccinella septempunctata, the seven-spot ladybird, is a widespread species originally native from Europe, Asia and Northern Africa. Because of its potential as a biological control agent of crop insect pests, several intentional introductions have occurred in the USA. As a result, the species is now widely distributed and established in North America. The broad geographic success of the species, predominant in most habitats of the Palaearctic and a successful invader of the Nearctic Region, may be due to its ecological plasticity, based on genetic and phenotypic polymorphisms. In the USA, C. septempunctata has been reported to compete with and displace several native Coccinellidae species, causing a decrease in their survivorship and abundance.
There are two subspecies within the species C. septempunctata: Coccinella septempunctata brucki Mulsant, 1866 and Coccinella septempunctata septempunctata Linnaeus, 1758, as recognized by the Integrated Taxonomic Information System (ITIS, 2009).
Rathour and Singh (1991) suggested that ovariole number can be used as a taxonomic character in Coccinellidae and that multiplication, reduction, and stabilization of ovariole number have occurred in the evolution of coccinellids. C. septempunctata has 62 ovarioles per ovary.
C. septempunctata passes through three stages: egg, larva and pupa, to develop into an adult. The eggs are elongate, oval and laid on plants, often near to prey. C. septempunctata, like most ladybird species, fix their eggs at one end so they are in an upright position. Eggs take approximately 4 days to hatch, although increasing ambient temperature reduces the length of the egg stage; at 15°C eggs take 10.3 days to hatch, compared to 1.8 days at 35°C (Majerus and Kearns, 1989).
The number of eggs laid per C. septempunctata pair was 284 and 524, respectively, feeding on Hyalopterus pruni and Schizaphis graminum under laboratory conditions, compared with 213 eggs/pair on H. pruni in the field (Varvara et al., 1982).
Larva
The larvae remain on the eggs for approximately 1 day post egg hatch. They eat the egg shells, those of neighbouring larvae and any infertile eggs. The larvae suck body fluid from aphids and as they grow, they will also eat legs and antennae. The fluid from their gut is regurgitated into the aphid allowing some pre-digestion before the body fluid of the aphid is sucked in. There are three moults and four larval instars. Prey density, temperature (Majerus and Kearns, 1989) and prey species (Obrycki and Orr, 1990) can affect the length of the larval stage. Larvae reared at 23±2°C and LD 16:8 on Acyrthosiphon pisum required an average of 13.1 days to complete development, compared to 16 days on Rhopalosiphum maidis (Obrycki and Orr, 1990). One hundred and thirty-four to two hundred and fifty individuals of S. graminum were consumed per larva of C. septempunctata (Varvara et al., 1982).
Rhoades (1996) published a key to the first and second instars that does not rely on colour patterns of live larvae, rather the relative placement and characteristics of the prominent setae on the tergum of the abdomen.
Pre-pupa
The fourth instar larva does not feed for at least 24 hours pre pupation. The tip of the abdomen is attached to the plant substrate; it is immobile and hunched. This is the pre-pupa stage.
Pupa
The final larval skin of the pre-pupa sheds right back to the point of attachment. At 20°C, the pupal stage lasts for 8.4 days. This stage is not completely immobile because it is able to raise and lower the fore region in response to perceived danger (Majerus and Kearns, 1989). The colour of the pupa is variable in some species and C. septempunctata develop into light orange pupae at high temperatures and dark-brown or blackish ones at low temperatures (Majerus and Kearns, 1989).
Prey type affects development time of C. septempunctata. Sattar et al. (2008) reported total larval and pupal duration as 18.3±0.53 and 4.9±0.58 days, respectively, when C. septempunctata were fed Aphis gossypii. Mean percent emergence of males and females was reported as 36.6±2.98 and 56.6±4.21, respectively. The male to female sex ratio was recorded as 1:1.5. When this coccinellid was fed five different aphid species, Arshad and Rizvi (2007) found that overall development time was significantly longer on Lipaphis erysimi.
Adult
The front of the pupal case splits to allow the adult to emerge. When first emerged, the wings and elytra are very soft and barely pigmented. The colouration develops over time and the red colour of the background deepens over the next weeks and months. The dark colours are derived from melanins and the lighter ones from carotenes (Majerus and Kearns, 1989). Although some adults vary considerably in colour pattern, C. septempunctata show little variation, although spot number ranges between 0 and 9, and variation in spot strength is said to be “considerable” (Majerus and Kearns, 1989). Typically, adults are red with seven black spots.
Average longevity was recorded by Kontodimas et al. (2007) as 94.9 days at a constant temperature of 25±1°C, 65±2% RH and 16L:8D. Average total fecundity, net reproductive rate and intrinsic rate of increase were found to be 1996.8 eggs/female, 1004.1 females/female and 0.118 females/female/day, respectively.
For detailed information on all coccinellid life stages, including mating, comparison of sexes and a key to British ladybirds, refer to Majerus and Kearns (1989). Also refer to Marzo (1982), who presented morphological observations of Rhynchota and Coleoptera spermatheca, including C. septempunctata, and Thornham et al. (2007) who studied sexual dimorphism in the distribution and biometrics of the palpal sensilla of C. septempunctata and a description of a new sensillum.
C. septempunctata is native to temperate Europe, North Africa and Asia, but has become established in North America, where it has been found hundreds and thousands of kilometres away from its original release site (Krafsur et al., 2005). Montana and Washington are thought to be the most westerly records in the USA (Rice, 1992).
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Native to temperate Europe and Asia, C. septempunctata is a voracious predator of aphids and as such has been employed in biological control programmes. Between 1956 and 1971 numerous attempts were made to introduce C. septempunctata (originating from France, India, Norway and Sweden) into North America, and although a subsequent generation of the ladybird was recovered later in the year in some areas of New Jersey, Ohio and California, no permanent establishment was found until 1973 (Angalet and Jacques, 1975). In June 1973, several individuals were found in Hackensack Meadowlands, Bergen County, New Jersey; this was thought to be due to accidental introduction (Angalet and Jacques, 1975). Later intentional introductions resulted in establishment in Connecticut, Delaware, Maine, New York, Oklahoma and Pennsylvania, USA (Majerus, 1994). The intentional release of this species into New Brunswick, Canada in 1959 failed to establish, but its occurrence now in Quebec is thought to be the result of accidental introduction or spread from Maine (Larochelle, 1979).
In a 1990 survey, C. septempunctata was found at high altitudes in the Rocky Mountains; records of this species in Montana and Washington are said to be the most westerly records in the USA (Rice, 1992).
Since becoming established in North America, C. septempunctata has been found hundreds and thousands of kilometres from its original release site (Krafsur et al., 2005).
The European ladybird, C. septempunctata has been intentionally introduced into North America for the biological control of aphid pests and is now established in various areas of the USA and Canada. Climate is described by Hoddle (2004) as a fundamental requirement for the establishment of a species outside its area of origin; the recipient location must be similar in climate to the area of origin. Due to the fact that C. septempunctata is a habitat generalist and can develop on various aphid species, further spread into neighbouring areas with suitable climatic and habitat conditions is probable.
Hodek and Michaud (2008) examined factors that could be responsible for the broad geographic success of C. septempunctata. The species is highly mobile and eurytopic, shows an inhibition in ovipositing in the presence of conspecific larval trails, which represents an adaptive advantage favouring increased egg dispersal and serves to lower the risk of offspring mortality due to cannibalism. C. septempunctata is able to suspend oviposition, and displays heterogenous voltinism and diapause tendencies, therefore some populations feed and reproduce on randomly occurring aphid populations. Other adaptations include pre-hibernating mating, the fact that there is no reproductive diapause in males and the tendency to produce offspring in excess of the carrying capacity of local food resources.
C. septempunctata is a generalist ladybird and as such develops on a wide range of aphids, and thus on a wide range of plants. It is described by Majerus (1994) as “found in most habitats [in Britain]”. Majerus and Kearns (1989) describe the habitat preference of this ladybird as “diverse” and Majerus (1994) stated that early stages have been found on over 250 species of plant native to Britain, and numerous imported and cultivated varieties. The plants listed are: stinging nettles, thistles, bedstraws, umbellifers, knapweeds, vetches, willowherbs, tansy, ragworts, fat hen, goose-foots, chamomiles, bramble, Scots pine, wheat, barley, Brassica spp., beans, peas, sugar beet and rape. In a study to establish the status of exotic and previously common ladybirds in South Dakota, Hesler and Kieckhefer (2008) reported that C. septempunctata was present in a wide range of habitats surveyed. It was the most abundant larval coccinellid in intercropped wheat-alfalfa, where it preyed on Hyalopterus pruni. This species has also been found under rocks in alpine tundra, and on a snow field in the Rocky Mountains, at elevations of 3475 m (Rice, 1992).
Majerus and Kearns (1989) also stated that a regular cycle of movement from one host plant to another throughout the year is displayed by some generalist coccinellids.
Rozek and Holecová (2002) studied C-banded karyotypes in the males of seven ladybird species, including C. septempunctata and reported that they possess 2n=20, n (males) = 9+Xyp.
Krafsur et al. (1992) used polyacrylamide gel electrophoresis to reveal the genetic diversity in exotic North American populations of C. septempunctata, recently spread across the northern Nearctic. Sixteen of the 28 putative loci were polymorphic; the average gene diversity for all loci was reported to be 0.1589±0.041. Gene frequencies were estimated at eight polymorphic loci in naturally occurring North American beetles from Arkansas, Delaware, Iowa, Kansas, New York, Oregon and Michigan. F2 beetles from colonies that originated in Eurasia were also studied, along with field-collected beetles from France, Greece and Sicily. Gene diversity among the Nearctic beetles was as great as that among those from the Palaearctic. Only 29% of the variance in gene frequencies was between USDA cultures, Palaearctic and Nearctic beetles; and 71% of the genetic variation was shared by beetles within the 21 subpopulations. There was no evidence of bottlenecks or drift among the Nearctic subpopulations, and gene flow was essentially unrestricted.
In a later study to identify the origins of C. septempunctata and thus help to explain movement and dispersal, and efficacy of the predator as an aphid control agent over large areas, Haubruge et al. (2002) employed random amplified polymorphic DNA (RAPD) analysis. Populations were sampled from Belgium and analysed for RAPD DNA variation; to quantify the genetic diversity within the species and to monitor the spatial foraging. They concluded that RAPD analysis can be a valuable technique for studies of intraspecific genetic variation in C. septempunctata.
Majerus et al. (1998) reported the occurrence of a melanic C. septempunctata (C. septempunctata f. purpuralis) male, collected from the field in the UK. It was mated with F1 females and the conclusion was that C. septempunctata f. purpuralis is controlled by a single recessive allele, with reduced viability.
Reproductive Biology
In general, female ladybirds have the capacity to lay over 1000 eggs each; however, this number is rarely reached (Majerus and Kearns, 1989). Reports for C. septempunctata vary from those such as Sattar et al. (2008) stating that a single female laid 177.0 ± 23.03 eggs during her entire life period, to an average total fecundity of 1996.8 eggs/female in life table studies by Kontodimas et al. (2007). In addition, the latter authors reported average longevity of 94.9 days, a net reproductive rate (Ro) of 1004.1 females/female, and intrinsic rate of increase (rm) as 0.118 females/female/day.
Environmental factors, ease with which a mate is found and the condition of the female affect the number of eggs laid (Majerus and Kearns, 1989). For example, Arshad and Rizvi (2008) observed the survival and fecundity of C. septempunctata at varying temperatures (18±1, 24±1°C and 28±1°C), 65±5% RH and 12 h L:12 h D photoperiod under laboratory conditions for two successive generations. They reported that the highest potential fecundity and net reproductive rate of C. septempunctata were obtained at 24±1°C (165.67 eggs/female and 41.09 females/female/generation, respectively) and the lowest at 28±1°C (146.63 eggs/female and 29.70 females/female/generation, respectively). A temperature of 28±1°C resulted in the maximum finite, intrinsic and annual rate of increase (1.0876, 0.0840 females/female/day and 2.04×1013/annum, respectively) and at 18±1°C the minimum values of these factors were observed (1.0794, 0.0764 females/female/day and 1.281×1012/annum, respectively). The minimum mean length of generation and doubling time were 40.77 and 8.26 days, respectively at 28±1°C and the maximum values were 48.27 and 9.08 days, respectively at 18±1°C.
Other factors affecting egg hatch include infertility; the condition and age of the parents, and time since the female last mated affect the fertility of the eggs (Majerus and Kearns, 1989). Sattar et al. (2008) reported 98.3±2.79% egg hatch and 82.2±6.20% survival of larvae to the pupal stage in biology experiments of C. septempunctata. Eggs are also vulnerable to predation by other predators (e.g. lacewings) (Majerus and Kearns, 1989).
Phoofolo and Obrycki (2000), studying phenotypic variation in reproductive traits of C. septempunctata and Propylea quatuordecimpunctata, found that 47 to 61% of C. septempunctata females laid their first batch of eggs within the first two weeks of their adult life. Repeatability estimates of daily parity for C. septempunctata populations were reported to be 0.32 for Iowa (USA), 0.35 for Delaware (USA), 0.28 for France, and 0.33 for Ukraine.
When aphid prey (Acyrthosiphon pisum) were removed, Kajita and Evans (2009) showed that C. septempunctata reduces oviposition. This is resumed when prey are again offered. The rapid responses to changes in prey availability shown by C. septempunctata is suggested by the authors as a contributing factor to the greater abundance and reproductive success of this introduced species relative to the native Coccinella transversoguttata in western North American alfalfa fields that exhibit widely varying pea aphid densities.
C. septempunctata undergoes oosorption as a means of reserving resources under poor prey conditions and enhancing future reproductive effort when prey conditions improve (Kajita and Evans, 2009).
C. septempunctata requires diapause prior to the onset of reproduction.
Physiology and Phenology
Hodek et al. (1989) studied the physiological state of C. septempunctata collected in mid-hibernation in Greece following exposure to 23.5±2°C and LD 18:16 (long-day conditions) or LD 12:12 (short-day conditions). It was reported that the delay in oviposition was similar under both short-day and long-day conditions. Oviposition rate and fecundity were higher under short-day conditions. Generally it was found that, the metabolic rate of females increased from an average of about 30 mm³ O2/h per individual at the onset of exposure to a maximum of about 120 mm³ O2/h per specimen. It was concluded that in warm greenhouses where the natural photoperiod is not modified, most adults collected in overwintering sites can be induced to reproduce prematurely in early winter.
Studying the phenology of this coccinellid in Greece, Katsoyannos et al. (1997) found that field-collected specimens underwent four complete and a fifth partial generation per year. Only adults of the first generation reproduced within the year they emerged. Adults of the first and fifth generations died before winter; those of the second to fourth generations overwintered successfully. The greatest numbers of eggs were laid by females of the first and second generations. Visual counts made in the open field at Kopais Plain in central Greece and on the summit of the adjacent Mount Kitheron indicated that all C. septempunctata instars were abundant in the plain between April and June, becoming scarce from July until the end of the warm period of the year following spring. C. septempunctata were not found in the plain in winter. C. septempunctata adults were present all year round on the mountain summit, singly and in aggregations, except in May. The most numerous arrivals of adults were noticed on the mountain in June and emigrations of adults from there were noticed from March until the end of April.
Nutrition
C. septempunctata is able to develop on a wide range of aphids (Majerus and Kearns, 1989) and Hodek and Honek (1996) state that over 20 aphid species are essential prey for this ladybird. Under laboratory conditions, the mean daily consumption of aphids by a pair of C. septempunctata was recorded as 32 individuals of Hyalopterus pruni and 41 of Schizaphis graminum, and 134-250 individuals of S. graminum were consumed per larva (Varvara et al., 1982). Sattar et al. (2008) reported that mean consumption of Aphis gossypii per C. septempunctata adult was 77.8±5.15, and 21.9, 55.9, 107.4 and 227.3 aphids were consumed by a single larva during 1st, 2nd, 3rd and 4th instars, respectively.
However, aphidophagous coccinellids such as C. septempunctata will feed on other food types. Triltsch (1999) found fungal spores (mainly conidia of Alternaria), pollen and thrips, together with other non-aphid arthropods, in the guts of field-collected adults and larvae. There are reports of it feeding on the greenhouse whitefly, Trialeurodes vaporariorum (Ravinder Kumar and Gupta, 2006), nymphs of the citrus psylla, Diaphorina citri (Gupta and Bhatia, 2000), hawthorn mealybug nymphs, Phenacoccus dearnessi (Cranshaw et al., 2000), the Colorado potato beetle (Leptinotarsa decemlineata) (Gusev et al., 1983) and Bemisia tabaci (Zhang et al., 2007). It is also cannibalistic (Varvara et al., 1982; Omkar and Maurice, 2009).
Dixon and Guo (1993) determined the direct and indirect effects of aphid abundance on egg and cluster size in C. septempunctata. It was found that when food supply varied, there was a tendency for cluster size and number of eggs produced per day to vary, but not egg size. Host density has also been shown to significantly affect aphid consumption by all larval instars. Solangi et al. (2007) found that consumption by C. septempunctata larvae significantly increased with increasing density of the mustard aphid, Lipaphis erysimi.
Giles et al. (2002) studied the influence of alfalfa cultivar (Medicago sativa) on suitability of Acyrthosiphon kondoi for the survival and development of Hippodamia convergens and C. septempunctata. It was found that the resistant lucerne cultivar (54H55) would have little to no effect on the nutritional value of A. kondoi for both ladybird species.
Associations
Majerus and Kearns (1989) stated that this species has been found overwintering with Adalia 2-punctata (2 spot), Coccinella 11-punctata (11 spot), Propylea 14-punctata (14 spot), Micraspis 16-punctata (16 spot), Psyllobora 22-punctata (22 spot), Aphidecta obliterate (larch), Calvia 14-guttata (cream-spot) and Exochomus 4-pustulatus (pine) ladybirds.
Environmental Requirements
When conditions such as temperature and food availability are unsuitable for development, the adults overwinter in almost any slightly sheltered position close to the ground (Majerus and Kearns, 1989), in aggregations (Honek et al., 2007). For a general overview of overwintering in ladybirds refer to Majerus and Kearns (1989), for example.
Under laboratory conditions, Hodek (1970) observed the termination of diapause in C. septempunctata, collected at the end of August from overwintering sites in southern Moravia. It was found that the termination of diapause in females exposed to constant temperatures of 0, 5 or 12°C or to fluctuating temperatures (range 5-12°C), for 3, 6 or 9 weeks and then kept with 18 h light at 23°C during the light period and 18°C during the dark one, was more effective at 5 and 12°C compared with 0°C. Moreover at all temperatures, the termination of diapause was greater in the 6-week than in the 3-week samples.
C. septempunctata are only active in daylight. Zotov (2009) showed that sensitivity to light, photopreferendum and locomotory activity are managed by endogenous circadian oscillators. Results indicated that sensitivity to light (100, 1000 or 7000 lux) was maximum in the daytime (periods of activity) and minimum at night (rest period) irrespective of temperature (17 or 26°C).
When studying altitudinal distribution of coccinellids in mountain spruce forests of Pol’ana Mountains, west Carpathians, in Slovakia at altitudes ranging from 600-1300 m.a.s.l., Selyemová et al. (2007) found that C. septempunctata was most abundant at the middle altitudes studied (900-925 m). This beetle has been found at elevations of 3475 m in the Rocky Mountains (Rice, 1992).
Various predators and parasitoids have been recorded attacking C. septempunctata; refer to Majerus (1994) for a detailed overview. Due to the relatively large size of a C. septempunctata larva, it may contain up to six Homalotylus eytelweini (Majerus and Kearns, 1989). Another gregarious parasite found in this species is Tetrastichus coccinellae; up to 25 have recorded from a single larva (Majerus and Kearns, 1989). A list of arthropod parasites and hyperparasites was published by Schaefer and Semyanov (1992), which included 14 Hymenoptera from six families, two Diptera from two families, and two ectoparasitic mites.
Rubtsov (1971) described and illustrated the mermithid Hexamermis coccinellae coccinellae n. subsp. found in C. septempunctata. Even though Matchanov et al. (1984) reported the presence of mermithids Hexamermis sp., Hexamermis albicans, Mermis sp. and Gastromermis sp. in C. septempunctata, they were only found in 0.4% of 10,350 insects examined, which included Hypera nigrirostris, Pentatomidae, two species of Tettigonidae and one locust. It was suggested that the climatic conditions of the areas studied (Bukhara and Navoi regions of Uzbekistan, USSR) were contributory to the low prevalence of infection.
Koyama and Majerus (2008) studied interactions between the parasitoid Dinocampus coccinellae and Harmonia axyridis and C. septempunctata. They stated that in Japan, both coccinellids are hosts to the wasp, but a higher proportion of C. septempunctata are successfully parasitized and reported that this was also the case in Britain, to a greater extent.
The eggs of C. septempunctata may come under attack from lacewings and coccinellids, both this and other species (Majerus and Kearns, 1989).
The larval and adult stages are mobile and thus able to disperse locally. It has been reported that since its establishment in North America, C. septempunctata has been found hundreds and thousands of kilometres from its original release sites (Krafsur et al., 2005).
Accidental Introduction and Intentional Introduction
C. septempunctata has been widely introduced as a biological control agent for the control of Aphis gossypii. Attempts to introduce it into North America between 1956 and 1971 failed, but it was subsequently found in New Jersey, USA where it is thought to have been accidentally introduced (Angalet and Jacques, 1975; Majerus, 1994).
Hoddle (2004) states that C. septempunctata has influenced the distribution and abundance of native coccinellid competitors by reducing their survivorship in local habitats, influencing dispersal dynamics and habitat use. For example, Elliott et al. (1996) documented the effect invasion by C. septempunctata had on native coccinellids in South Dakota, USA on lucerne, maize and small grains. Coccinellids were observed 13 years post invasion and 5 years after. It was found that the structure of native coccinellid communities differed significantly for years before compared to years after invasion.
Turnock et al. (2003) studied the abundance of some coccinellids before and after the introduction of C. septempunctata to Manitoba, USA in 1988. The relative abundance of the more common native coccinellids was determined from D-Vac Insect Net® and sweepnet samples in lucerne in 1983-2001, by sweepnet and visual sampling in field crops and other vegetation in 1989-2001, and by transect sampling of aggregations of coccinellines in spring and autumn on the shore of Lake Manitoba from 1989 to 2001. It was found that the relative abundance of Coccinella transverso guttata, Hippodamia convergens, Hippodamia parenthesis, and Coccinella trifasciata has decreased since the establishment of C. septempunctata. It was thought that the decline in abundance of these species was caused by their competitive displacement by C. septempunctata.
Similarly, a study by Brown and Miller (1998) reported that C. septempunctata was dominant in the fauna of the tribe Coccinellini from 1989 to 1994 in eastern West Virginia on apple. However, Harmonia axyridis dominated in 1995 and continued to do so in the guild coccinelline on apple. Furthermore, Brown and Miller (1998) reported a displacement of C. septempunctata with H. axyridis, which provided better control of Aphis spiraecola on apple in the study area.
More recently, in South Dakota, Hesler and Kieckhefer (2008) reported the decline of three previously common ladybirds (Adalia bipunctata, Coccinella transversoguttata richardsoni and Coccinella novemnotata), while the invasives, C. septempunctata and H. axyridis had established there.
Gardiner et al. (2009) carried out a four-USA-state wide survey of native and exotic coccinellids, including C. septempunctata and concluded that grassland dominated landscapes with low structural diversity and low amounts of forested habitat may be resistant to exotic coccinellid build-up, particularly H. axyridis and therefore represent landscape-scale refuges for native coccinellid biodiversity.
Snyder et al. (2004) discuss intraguild predation (IGP) and successful invasion by exotic ladybirds. Their results suggested that larvae of native species face increased IGP following invasion by C. septempunctata and H. axyridis, which may contribute to the speed with which the exotics displace the natives after invasion.
Furthermore, in a study to determine under what conditions an invasion results in displacement or co-existence, and to determine rules that underlay combinations of IGP and intraspecific predation (ISP), Rijn et al. (2005) stated that ISP and IGP seemed to be related to larval size differences, where overall the larger species had a greater overall advantage. However, the authors also surmise that larger larvae require more food thus having a disadvantage in terms of resource competition. It was concluded that the estimated levels of ISP and IGP and competitive ability of interacting species could not fully explain invasion by H. axyridis and C. septempunctata.
During mass occurrences of C. septempunctata, people have been reportedly bitten by this species (Eichler, 1971). The population explosion of ladybirds, mostly C. septempunctata, in Britain in 1976 is frequently recounted. During this time there were numerous reports of people being attacked by them. The ladybirds were in search of food and biting into anything they landed on to test suitability as a food source. On biting, they inject a small amount of digestive enzymes, which on reacting with the chemical defences of the body produce a stinging sensation (Majerus and Kearns, 1989). Other reports of this species being a nuisance are from the German Baltic Sea coast (Dambeck, 2009) and Albena, Bulgarian Black Sea coast (Krell and Britton, 2009).
C. septempunctata has been widely introduced as a biological control agent for the control of aphid pests under glasshouse conditions (e.g. Yarkulov, 1978; Valério et al., 2007). The ability of C. septempunctata to regulate and control aphid pests in the field has been well documented, often as part of a natural enemy complex (e.g. Shanthi et al., 2009). It is often listed as a natural enemy occurring under field conditions in a wide variety of crops, such as pomegranate orchards (Öztürk et al., 2005), sour cherry orchards (Prunus cerasus) (Özkan et al., 2005), mustard fields (Vekaria and Patel, 2005), and ground nut (Sahayaraj and Martin, 2003) and horse bean (Vicia faba minor) (Sadej, 2000) crops, to name but a few.
After studying field and computer generated data, Gosselke et al. (2001) concluded that without antagonists, including C. septempunctata, winter wheat-cereal aphids (Sitobion avenae, Rhopalosiphum padi and Metopolophium dirhodum) would cause economically important yield losses in two out of three cases. As part of a predator complex, C. septempunctata prevented Aphis fabae from exceeding economic damage thresholds in sunflower in Romania (Voicu et al., 1987).
In contrast, Immik et al. (2004) studying the biological control of woolly aphid, Eriosoma lanigerum, stated that the release of C. septempunctata, Chrysoperla carnea and Adalia bipunctata larvae had little effect on the aphid population and could not be economically justified.
The value of C. septempunctata as a pollinator of the endemic and endangered plant, Disanthus cercidifolius, in China (Xiao et al., 2009), and in mango (Singh, 1989) has also been documented.
Marzo (1982) studied the spermatheca of Rhynchota and Coleoptera, including C. septempunctata and reported that even among species not systematically related, similarities were observed in the shape of the spermathecae; seven main forms were found.
In a study of reflex bleeding in ladybirds, Jong et al. (1991) discussed the phenomenon in relation to the possibility that Adalia bipunctata is a Batesian mimic of C. septempunctata.
Roy et al. (2008) studied the effect of Beauveria bassiana on Harmonia axyridis, C. septempunctata and Adalia bipunctata. Results showed that 80% mortality of C. septempunctata was achieved with a dosage of 109 conidia ml-1.
Chemical control
The ability of C. septempunctata to reduce pest aphid populations under natural conditions in the field and in protected environments is widely recognised and this species has been extensively introduced as a biological control agent for the control of aphid pests. Therefore the effects of chemicals on this coccinellid are in the context of non-target effects under laboratory conditions (e.g. Ullah, 1977 in part; Ahmad and Ahmad, 2009) and in the field (e.g. Alexandrakis et al., 2005). For example, Ullah (1977) studied the effects of pesticides to control A. gossypii on C. septempunctata and found monocrotophos to be highly toxic to the predator. Similarly, Ahmad and Ahmad (2009) reported that fenazaquin and quinalphos were highly toxic to adults of C. septempunctata.
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