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
The multicolored Asian ladybeetle, Harmonia axyridis (Coleoptera: Coccinellidae), was first reported in southern Canada in 1994. In this study, we examined the status of the ladybeetle in Quebec agroecosystems seven to ten years after its arrival. We integrated the findings from eight independent field studies carried out in pome fruit, grapes, medicinal crops, field corn, sweet corn, sweet pepper, lettuce, and soybean. Nine aphidophagous and 6 coccidophagous coccinellid species were sampled on these crops. Among these aphidophagous species, three invasive (H. axyridis, Coccinella septempunctata and Propylea quatuordecimpunctata) as well as one indigenous species (Coleomegilla maculata lengi) were consistently present. Higher richness was observed in perennial crops, where the 6 coccidophagous coccinellids were almost exclusively present. Higher abundance of aphidophagous coccinellids was observed in field and sweet corn. The multicolored Asian ladybeetle was a dominant species of the coccinellid assemblage in all crops monitored.
In Hymenoptera and Heteroptera, the absence of micropyles is one criterion for categorizing an egg as trophic. Undeveloped eggs are observed in more than 90% of the egg clusters of the ladybird beetle Harmonia axyridis Pallas. Traditionally, these undeveloped eggs are regarded as "trophic eggs." The surfaces of the eggs of H. axyridis were examined using scanning electron microscopy and the presence of micropyles in the shells of developing and undeveloped eggs determined. Micropyles are circularly distributed around the top of eggs and present in both developing and undeveloped eggs. The number of micropyles in the shells of developing and undeveloped eggs did not differ significantly. Our results indicate that the undeveloped eggs of H. axyridis have micropyles, suggesting that the mechanisms regulating the production of undeveloped eggs in H. axyridis differ from those resulting in the production of trophic eggs by Hymenoptera and Heteroptera.
We determined if mature ladybirds use colour to initially find suitable host plants. We also determined whether ladybird beetles are capable of associating characteristics such as colour with the presence of prey. Here, we show that the multicoloured Asian ladybird beetle, Harmonia axyridis, has a differential response to yellow compared to green colours. Naive ladybirds, of both sexes, make significantly more visits and spend more time on yellow vs. green coloured pillars. After pairing yellow and green colours with the presence or absence of aphid prey, ladybirds alter their foraging behaviour. Beetles conditioned to having food on both pillar colours exhibited the same responses as naive beetles, while beetles conditioned to only yellow or green pillars did not exhibit a preference for visiting or spending time on different colours. However, there was a trend towards females spending more time on pillar colours on which they received reinforcement, and males spending more time foraging on colours opposite to that which they were reinforced. Thus, H. axyridis is capable of responding to cues such as colour, and its foraging behaviour can be altered as a result of prior experience.
Factors were examined that could be responsible for the predominance of Coccinella septempunctata (C7) in most habitats of the Palaearctic and for its successful invasion of the Nearctic Region. C7 is euryphagous, but less polyphagous than Harmonia axyridis or Coleomegilla maculata in that it cannot develop or reproduce on non-aphid food. The intraguild status of C7 is intermediate. Although adult size is large, preimaginal stages are palatable to those of H. axyridis and Adalia bipunctata, whereas it is not an intraguild predator of these species. Although these traits appear to be neutral or negative, many aspects of population plasticity are advantageous for C7, often acting in concert with a bet-hedging strategy. Given its high mobility and eurytopy, the inhibition of oviposition in the presence of conspecific larval trails represents an adaptive advantage that favors increased egg dispersal and lowers the risk of offspring mortality due to cannibalism. The ability to temporarily suspend oviposition, combined with heterogenous voltinism and diapause tendencies, enable a portion of C7 populations to feed and reproduce on unpredictably occurring aphid populations. An absence of reproductive diapause in males and pre-hibernation mating are other significant adaptations, along with the tendency to produce offspring in excess of the carrying capacity of local food resources. We suggest that one explanation for the broad geographic success of C7 resides in an ecological plasticity that is based on both genetic and phenotypic polymorphisms.