Non-random mating in Adalia bipunctata (the two-spot ladybird). II. Further tests for female mating preference

Abstract

Tests for non-random mating in laboratory stocks of Adalia bipunctata showed that female twospot ladybirds from 'isofemale lines', which had formerly mated preferentially with melanic males, now mated at random. In an attempt to obtain new stocks in which females mated preferentially, we isolated 'isofemale lines' from a natural population at Keele, but we found no evidence of females mating preferentially within these stocks. We did, however, observe two interesting phenomena, not previously reported from Keele populations of Adalia bipunctata, or from laboratory stocks derived from the Keele population. Firstly, much of the variation in male mating success, which we observed, could be explained by the date on which the mating tests were carried out. Secondly, there was significant heterogeneity in sex ratios among some of the stocks. We discuss the potential importance of both these phenomena when designing experiments and interpreting data regarding non-random mating in Adalia bipunctata.

Sexual activity in Coccinellidae (Coleoptera): a review

“…Negative frequency dependence of the advantage will thus help maintain the polymorphism (O'Donald & Majerus, 1984, 1985. Sev eral years later the preferential mating was not found (Kearns et al, 1990(Kearns et al, , 1992 in the populations studied by Majerus, O'Donald and co-workers.…”

Sperm competition and melanic polymorphism in the 2-spot ladybird, Adalia bipunctata (Coleoptera, Coccinellidae)

“…Field data have provided evidence for different forms of sexual selection as sociated with the different colour morphs: (i) a female preference for melanic males has been described in some British populations (Majerus et at., 1982;O'Donald & Majerus, 1988; but see Kearns et al, 1990Kearns et al, , 1992; (ii) a frequency-dependent mating advantage for melanics has been recorded (Muggleton, 1979;Kearns et at., 1990); (iii) a general mating advantage to melanics over non-melanics was found in The Netherlands (Brakefield,1 984c). An understanding of the extent of sperm competition in this species is necessary to interpret the consequences of any deviation from random mating.…”

Temporal effects of multiple mating on components of fitness in the two-spot ladybird, Adalia bipunctata (Coleoptera: Coccinellidae)

“…Thus far, no evidence for direct nutritional benefits from multiple mating has been found in the twospot ladybird (Ransford, 1997), although females who mate only once may eventually suffer from depleted sperm supplies (Majerus, 1994). Pre-copulatory female mate choice associated with colour pattern has been observed in some populations (Majerus et al, 1982(Majerus et al, , 1986; but see Kearns et al, 1990Kearns et al, , 1992 but so far there is no evidence for post-copulatory female choice, with sperm competition patterns suggesting random mixing of ejaculates within a female (Ransford, 1997).…”