Insects have provided much of the best evidence to date concerning possible costs and benefits of multiple mating, and here we investigate the benefits of polyandry in the two-spot ladybird, Adalia bipunctata, by attempting to replicate the highly promiscuous mating system in this species. We compared the temporal pattern of reproductive success of females mated multiple times to one male with that of females mated an equal number of times to multiple males, and found transient differences in offspring production and hatch rate over time. Our data suggest that polyandrous females benefit from multiple mating in some circumstances, but the patterns are complex. Following how both the costs and benefits to mating accrue over time will be necessary if we are to fully understand why polyandry evolves.
In central Europe Adalia bipunctata (L.) occurs in two main colour morphs (typical, melanic), and A. decempunctata (L.) occurs in 3 morphs (spotted, chequered, dark). Temporal variation in the relative frequency of morphs was recorded in populations of the Czech Republic where geographic variation in morph frequency is low. Seasonal trends were investigated in samples collected by a light-trap run daily from March to November for 14 years. In A. bipunctata the melanic form was more abundant in autumn than in spring but the difference was not significant. In A. decempunctata morph proportions did not change seasonally. Samples were also collected by sweepnet from stands of many plant species. In both Adalia species the morph proportions did not differ significantly among collections made on different plants. Long-term changes in morph proportions were analysed by pooling annual samples over all host plants. In A. bipunctata, sampled in 15 years between 1971-2004, there was no significant change in proportion of typical (90.1%) and melanic (9.9%) forms. In A. decempunctata, sampled in 12 years between 1976-2004, the proportions of "spotted" (mean over the years 29.4%), "chequered" (42.2%) and "dark" (21.3%) morphs varied between years. There was a trend toward an increasing proportion of the spotted form in the 2000s compared to the 1970s and 1980s.
Lady beetles (Coleoptera: Coccinellidae) are a classical group for studying the mechanisms that determine local and temporal trends in colour polymorphism. Here we report long term trends in variation in the percentage of different morphs in a population of Hippodamia variegata (Goeze) at Štúrovo, Slovakia (47°48´N, 18°43´E). The morphs differ in the number and location of the spots on their elytra. Beetles were sampled from stands of herbaceous plants using a standard method each year in August over a period of 74 years from 1937 to 2011. Twenty two morphs (out of 74 possible) were recorded in a total sample of 6,984 individuals. Four dominant morphs made up 90% of the total sample and varied in their annual frequency independently of one another. Frequency of "pale" morphs (0–3 spots per elytra), supposedly favoured by a warm climate, increased from 1981 to 2000s’ during a period of climate warming, but only after a decrease that took place between 1937 and 1981, which did not parallel a change in climate. Moreover, the differences in the extent of the melanization of the elytral surface are too small to significantly affect thermoregulation in the different morphs. Therefore, the results presented do not provide unequivocal support for climate change determining the long term trends in the variation in the proportions of the different morphs., Alois Honek ... [et al.]., and Obsahuje seznam literatury
Ten aphid species wcre used as prey for Adalia bipunctata and six of them (Euceraphis betulae, Cavariella konoi, Liosomaphis berberidis, Acyrthosiphon ignotum, Aphis farinosa and Macrosiphoniella artemisiae) are new essential preys for this coccinellid. Eucallipterus tiliae and E. betulae were the most suitable prey according to the rate of larval development, larval mortality, adult fresh weight and coccinellid abundance in the field. They are followed by L. berberidis, C. konoi and Tuberculatus annulatus. M. artemisiae and A. ignotum are also very profitable food in the laboratory, but they do not occur in the field together with A. bipunctata. A. farinosa from Salix caprea and Aphis fabae from Philadelphus coronarius were not very suitable as food due to the larval mortality (27% and 23%, respectively). A. fabae from Atriplex sagittata was an unsuitable prey: larval mortality was 67% and the adults that emerged as the survivors had the lowest weight recorded in this series of experiments. Aphis spiraephaga was also unsuitable prey: all 1st instar larvae of A. bipunctata died, even though slowly.
The ladybird beetle Harmonia axyridis Pallas was investigated under laboratory conditions to clarify the relationship between food abundance or scarcity and ovarian development or oosorption. Four conditions were used: (1) fully fed for 24 h, (2) 24-h starvation, (3) 48-h starvation, and (4) 24-h starvation followed by 24-h re-feeding. Body length and initial body weight were not significantly related to the number of ovarioles per female. Both starvation conditions significantly increased the percentage of oosorptive individuals and ovarioles per female, and significantly decreased the percentage of mature ovarioles per female. Re-feeding for 24 h after a 24-h starvation resulted in a significantly higher percentage of mature ovarioles per female; however, the percentage of mature ovarioles remained lower than in the fully fed condition. Oosorption mainly occurred during the intermediate developmental stage of the ovarioles. The rates of ovarian development and oosorption in predatory H. axyridis were much faster compared with those in herbivorous ladybird beetles. Body length, initial body weight, and the number of ovarioles were significantly correlated with the number of eggs laid during the last 24 h of each experimental condition. From an analysis of the weight loss and the number of eggs laid during the last 24 h of each experimental condition, it appears that the realized weight of the eggs may be directly determined by the amount of food digested by the adult. The ovarian development and oosorption were asymmetric in the right and left ovaries. These may be important strategies for oviposition in H. axyridis, because selective provision of maturing ovarioles in the right or left ovary with digested nutrients would favor their development. In addition, the energy loss through oosorption during the intermediate developmental stage of oocytes would be less than the energy loss resulting from the resorption of mature oocytes. Therefore, one role of the ovary in H. axyridis, in addition to egg production, might be as a kind of energy storage system for increasing reproductive success. An immediate start of ovarian development under favorable feeding conditions and rapid oosorption during food scarcities may be an adaptive ovipositional and survival strategy for female adults of H. axyridis in response to heterogeneous and fluctuating resource conditions.
The coccinellid Harmonia axyridis is a recent arrival in the UK and is an intraguild predator of the entomopathogenic fungus Pandora neoaphidis. Harmonia axyridis entirely consumes P. neoaphidis-sporulating cadavers and this may have a negative effect on the epizootic potential of P. neoaphidis. Here we assessed within plant transmission, and between plant vectoring, of P. neoaphidis in the presence of either H. axyridis or Coccinella septempunctata, a native coccinellid that only partially consumes fungal cadavers. Transmission was greater in the presence of coccinellids, with 21% of aphids becoming infected with the fungus whilst only 4% were infected in the control. However, there was no significant effect of coccinellid species or sex on fungal transmission. Between plant vectoring occurred infrequently in the presence of both species of coccinellid. The effect of H. axyridis on P. neoaphidis transmission is, therefore, likely to be similar to that of the native coccinellid C. septempunctata. and Patricia M. WELLS, Jason BAVERSTOCK, Michael E.N. MAJERUS, Francis M. JIGGINS, Helen E. ROY, Judith K. PELL.
One of the factors affecting the effectiveness of predatory coccinellids in an aphid infested crop is the food specificity of the predator. The response towards six species of aphids (Sternorrhyncha: Aphididae) was therefore tested in one of the most abundant aphidophagous coccinellids in Bulgaria - Propylea quatuordecimpunctata (L.) (Coleoptera: Coccinellidae). All aphid species studied (Acyrthosiphon pisum Harris, Aphis craccivora Koch, Eucallipterus tiliae (L.), Euceraphis betulae (L.), Phorodon humuli (Schrank) and Myzus persicae (Sulzer) cultured on transgenic Bt and conventional (non-Bt) potatoes were suitable food according to the rate of larval development, larval mortality and adult fresh weight. Females of P. quatuordecimpunctata fed with M. persicae cultured on Bt potato, or on non-Bt potato or on a mixture of M. persicae from Bt potatoes and A. craccivora, laid a little more eggs than those fed only with A. craccivora.
I hypothesized that sibling cannibalism is one of maternal investment in that a female controls sibling cannibalism. To test the hypothesis, I conducted a laboratory experiment and field observations to investigate sibling cannibalism in relation to cluster size and cluster site in the ladybird beetle, Harmonia axyridis Pallas. In the laboratory experiment, cluster size significantly affected the number of cannibalized eggs per cluster (R2 = 0.516), while cluster size was significantly affected by the oviposition interval. Furthermore, there was a marginally significant positive relationship between cluster size and the percentage of sibling cannibalism per cluster. In the field, cluster size and the direct distance from a cluster site to an aphid colony (an indicator of intensity of non-sibling cannibalism) significantly affected the number of cannibalized eggs per cluster (R2 = 0.472). Furthermore, there was a significant positive relationship between the direct distance from a cluster to the nearest aphid colony and cluster size. However, there was not a significant relationship between the distance and the percentage of sibling cannibalism. These results may be caused by the weakness of the female's power to control sibling cannibalism. Thus, a female H. axyridis controls cluster size through the intensity of non-sibling cannibalism, which may be one of oviposition strategies in this species.
The development of Adalia bipunctata larvae feeding on the grain aphid Sitobion avenae was investigated at 15, 20 and 25°C and two different levels of food supply. Increased temperatures accelerated development and reduced mortality rates. A reduced food supply slowed down development and increased mortality at all life stages. The total food intake of larvae ranged from 24-65 mg, which is equivalent to up to 190 aphids. Larvae compensated for low food supply by reducing development rates, high prey exploitation efficiencies, reaching up to 100%, and by high prey-biomass conversion efficiencies, reaching over 40%. The findings are discussed under the aspect of suitability of A. bipunctata as a biological control agent for greenhouse-specific aphid pest species.
1_The ladybird beetle Harmonia axyridis (Pallas 1773) has been used for biological control in several countries. However, it became invasive in some of those countries. Coccinella septempunctata (Linné 1758) is a native species in Europe. It feeds mainly on aphids and can be very abundant. As far as is known there are no effective natural enemies of the grape phylloxera Daktulosphaira vitifoliae (Fitch 1855) in Europe. The potential of the above two ladybird species for reducing the abundance of the grapevine pest D. vitifoliae has not been previously investigated. In this study, the consumption and developmental parameters of H. axyridis and C. septempunctata fed on D. vitifoliae were determined in the laboratory. In a field trial, the occurrence of H. axyridis on grapevines with or without leaf galls of D. vitifoliae was compared. In contrast to C. septempunctata, H. axyridis was able to complete its development using D. vitifoliae as a source of food. In addition, adult H. axyridis consumed significantly more D. vitifoliae eggs than C. septempunctata. Within 24 h H. axyridis consumed up to 1400 eggs of D. vitifoliae. However, based on the fitness parameters "developmental time", percentage "survival" and "adult weight", this diet was less suitable for H. axyridis than the eggs of Ephestia kuehniella., 2_During field observations over a period of two years H. axyridis was repeatedly observed feeding on grape phylloxera leaf galls, which indicates that H. axyridis uses grape phylloxera as prey. H. axyridis was significantly more abundant on leaves with leaf galls of D. vitifoliae than on leaves without galls. C. septempunctata was rarely found on grape leaves with or without leaf galls. These results indicate that overall H. axyridis, unlike C. septempunctata, is a predator of D. vitifoliae and could potentially reduce grape phylloxera numbers in vineyards., Susanne Kögel, Manuela Schieler, Christoph Hoffmann., and Obsahuje seznam literatury