|Coccinella septempunctata |
common name Seven-spot Ladybug (or Seven-spotted Ladybug)
Diverse. It is a habitat generalist and is found throughout most habitats (Acorn, 2007; Kearns & Majerus, 1989) where significant prey, especially aphids is available (Majerus, 1989).
According to studies done in Europe, adults emerge in late March or early April. The adults were observed mating a week or two after their emergence. The second generation adults emerged in June. While the young (second generation) females rarely mate until they have over-wintered, young males will mate with older (first generation) females. This creates a partial second generation (Majerus, 1994). In Alberta, it is common for this specie to produce three generations in one year (Acorn, 2007).
5.5-7.8 mm long. A red or orange-red ladybug with seven black spots (Acorn, 2007; Belicek, 1976). Although it commonly has seven spots the number of spots can range from 0-9 (Majerus & Kearns, 1989). This makes it easily confused with nine-spotted ladybug, but nine-spotted ladybugs have a pale orange colour and a dark line where the wing covers meet (Acorn, 2007). In Europe, it can be confused with scarce seven-spot ladybug (Coccinella magnifica). Coccinella septempunctata have one small white triangular mark on the underside of the thorax under the middle pair of legs on each side. Whereas, C. magnifica have two small triangular marks on the underside of thorax, one under each the middle and hind pair of legs on each side (Majerus & Kearns, 1989).
In a healthy larva, the first instar takes 22.4%, the second takes 18.4%, the third takes 17.2% and the fourth takes 41.9% of the total development time (Hodek & Honek, 1996). The larva will stop feeding 24 hours before pupating. When the pupa first emerges its elytra is soft and lacks pigment (ADW, 2012). The colouration happens over time and depends on the environment e.g. light orange under 35°C and 55% relative humidity, but dark brown under 15°C and 95% relative humidity. An increase in temperature above 200C for larval rearing has a negative effect on the weight of adult beetles e.g. increasing the temperature form 20°C to 25°C decreases the weight from 39 mg to 35.5 mg (Hodek & Honek, 1996). Sexually mature males will copulate by mouthing a female. Immature and females that are ready to lay eggs will resist this behavior. Individuals may mate multiple times to increase fecundity. Females eject spermatophore, for reason unknown. A female can lay anywhere from 200 to 1000 eggs. When eggs are being ova posited, females will avoid areas with the eggs of same species and will only deposit around 15 eggs at a spot. Breeding starts during spring/early summer and continues into fall (ADW, 2012).
They are an invasive species that are not on any conservation list, nationally or internationally due to their relative abundance (ADW, 2012).
It is polyphagus, primarily feeding on aphids. Various different aphids are essential for development. Adults dislike artificial food (Hodek, 1973). If food is low adults and larvae will eat their relatives and pollen (ADW, 2012).
Before it was introduced to North America between 1951 and 1970, its range extended throughout Europe and Asia. Now it is commonly found throughout most of North America (Acorn, 2007; ADW, 2012).
Bright colour in adults deters most predators away but some of the known predators are spiders, birds, small mammals and other ladybugs that will prey on larvae and eggs (ADW, 2012).
|species page author||Saran, C.||2013 |