30. Observations on the Life‐History, Biology, and Genetics of the Lady‐bird Beetle, Adalia bipunctata (Mulsant)

Abstract

Summary. Adalia bipunctata has so many varieties that it is highly suitable for the needed study of inheritance of normally occurring variations. Adalia can be mated in captivity with ease, but their cannibalistic habit makes it very difficult to rear them satisfactorily in large numbers. The time passed in the various stages is variable, depending not only on the food, hut also on the temperature, to which all stages, but especially the pupal, make a rapid response. Little is known of either hibernation or migration, but apparently both septempunctata and bipunctata tend to collect in numbers in the spring and autumn, and may at times be found hibernating, piled upon one another, similar to the “masses” of Hippodamia found in the western U.S.A. There is no evidence of dominance in crosses between the two main forms–the Red “type” and the Black (var. 4‐maculata and var. 6‐pustulata). Eleven ma tings of Red produced only the Red type. Black and Red forms also occur in G. variabilis, and, as in bipunctata, neither is dominant. The pronotum of the Black form is darker than that of the Red, but there is no progressive blackening of the pronotum of the Red coincidentally with the increase in the size of the black spots of the elytra. Although it is possible to make a series from pure red elytra on the one hand through various patterns to pure black on the other, this cannot be regarded as proof that the variations are merely fluctuating. The percentages of the variations is, as far as is known, approximately stable, and certain types are far more common than others. These facts, combined with the observation that the children tend to show the variations of the parents, strongly suggest that there are probably certain points of genetic stability, and that only analysis is needed to show that there is some regular method of inheritance.

Food Relationships

“…This defence seems successful only at low temperatures; at higher temperatures the coccinellids can ingest the glue. A similar defence mechanism was reported in Hyalopterus pruni against A. bipunctata (Hawkes 1920 ). The monophagous aphid, Aulacorthum nipponicum , feeding exclusively on Paederia foetida , is seldom attacked by coccinellids.…”

“…This allelochemical may be the reason why coccinellids reject this prey, although Hawkes (1920) suspected that the intense colour of the aphid was probably a warning. In other examples, unpalatability is connected with a waxy surface , as in Brevicoryne Adult weight (mg) glucosinolate degradation, was detected in B. brassicae but not in M. persicae (Francis et al 2000 ).…”

“…Hyalopterus pruni was described as unsuitable for A. bipunctata by Hawkes (1920) . It was rejected by larvae of A. decempunctata immediately on piercing the body wall.…”

Diapause/Dormancy

“…Migration is initiated by take -off during the calm of morning: the in walls, in lofts, or behind windows and even in rooms (e.g. Hawkes 1920, Semyanov 1970. However, recently it has been replaced by Har.…”

Observations on the Behaviour and Mortality in Coccinellidae Before Dispersal From the Egg Shells.

“…Even when coccinellid populations are low there is a certain degree of mortality during the egg stage, for some eggs are apparently infertile and some unhatched larvae may be destroyed by larvae already hatched from the same batch. Hawkes (1920) observed that some eggs of Adalia 2-pnctata hatched earlier than others and that approximately a quarter of the larvae were eaten before dispersal. Smee (1922) also noted that newly-emerged larvae attacked unhatched eggs and that some eggs were infertile.…”