Several studies have demonstrated that the invasive ladybird Harmonia axyridis is a strong intra-guild predator of native species of ladybird. Laboratory studies have shown that H. axyridis can be an intra-guild predator of aphid predators other than coccinellids, including the hoverfly Episyrphus balteatus and lacewing Chrysoperla carnea. However, little is known about the effect of intra-guild predation (IGP) by H. axyridis on hoverfly and lacewing populations in the field. In the present study molecular analyses were used to detect the DNA of E. balteatus and C. carnea in the gut contents of H. axyridis. Primers for the syrphid and chrysopid prey were designed and feeding experiments performed to determine how long prey DNA remains detectable in the guts of this ladybird. DNA detection was influenced by the life stage of the predator and species of prey. Meal size did not affect detection time, except when fourth instar individuals of H. axyridis were fed 10 eggs or one second instar of C. carnea. Predator weight, sex and morpho-type (melanic/non-melanic) did not influence DNA detection. The half-life of the time for which the DNA of the prey remained detectable was calculated for each predator-prey combination, and ranged from 8.9 to 52.4 h. This method can be used to study the ecological importance of IGP by H. axyridis on aphidophagous predators other than coccinellids in the field., Brecht Ingels ... [et al.]., and Obsahuje seznam literatury
The Old World ladybird Coccinella septempunctata has rapidly established itself as an abundant, widespread species throughout North America. Overwintering individuals of this species, and of native ladybirds, were collected from early season alfalfa in northern Utah during the period of initial establishment of the invader (1989 to 1999), and were measured for body size. Adult body size can vary widely within insect species, often reflecting differential success of individuals as immatures in obtaining food. Here I examine patterns of ladybird body size to address two questions associated with the establishment of C. septempunctata: (1) is there evidence for adverse impact on native species?, and (2) why has the invader has been so successful in establishment? As an indirect test of adverse competitive effect of the invader on native species, I determined whether mean body size of adults of the five most common native species (Coccinella tranversoguttata, Hippodamia convergens, H. quinquesignata, H. sinuata, and H. tredecimpunctata) declined over the period 1991-1997 as the invader increased rapidly in abundance. No such decline was observed for any of these species, thus providing no evidence that the invader's establishment has significantly increased scramble competition for food among immature ladybirds. I also compared body size distribution of the invading species with that of native species. The invader was distinctive in having particularly large variation in body size among individuals (i.e., in having relatively high proportions of both unusually large and small individuals). Such results are consistent with the hypothesis that the invader's success derives from being a generalist with much "ecological flexibility" in regard to the conditions under which it engages and succeeds in reproduction.
The effect of multiple matings on the readiness with which mating occurred, fecundity, egg viability and adult longevity in the aphidophagous ladybird beetle, Coelophora saucia (Mulsant) (Coleoptera: Coccinellidae), was investigated under laboratory conditions. The time to onset of mating after previous pairing was found to decrease with increase in the number of matings. Multiply mated females had a higher fecundity and egg viability than single mated females. The trends in the results were analyzed using both binomial regression and the Gompertz equation. The best fitting curve was that based on the binomial equation, which indicates that 95% of the maximum theoretical fecundity was attained after mating 11 times and 95% of the maximum theoretical egg viability after mating 3 times. Unlike previous studies on ladybirds, a slight but statistically significant increase in female longevity was observed with increase in number of matings indicating that the male ejaculate might provide a supply of nutrients.
We investigated food niches, diet diversity and individual food specialization of the larvae and adults of four species of ladybirds, Sospita vigintiguttata (L.), Calvia quindecimguttata (F.), C. quatuordecimguttata (L.) and C. decemguttata (L.), co-occurring in European alder carr forests. The first two species are considered to be strict habitat specialists associated with alders (Alnus spp.) in marshy forests and the other two are less habitat-specialized, inhabiting various deciduous trees and shrubs. Our investigations were based on the analysis of food remains in frass produced by field-collected ladybirds. In each of the species studied, adults had more diversified diets than larvae based on Levins' D index of diversity. The most diverse diet recorded for adults was that for S. vigintiguttata followed by C. quatuordecimguttata, C. quindecimguttata and C. decemguttata. The diversity of larval diet was higher for the habitat specialists, C. quindecimguttata and S. vigintiguttata, than for the more habitat-generalists Calvia decemguttata and C. quatuordecimguttata. Although the main type of prey recorded for both adults and larvae of each of the species studied was aphids, other types of prey made up a relatively high part of the diet of different species/stage combinations. Psylla alni (L.), for example, was frequently recorded in the frass of adults and larvae of S. vigintiguttata and of adults of C. quatuordecimguttata and chrysomelid larvae commonly in the frass of adults and larvae of C. quindecimguttata. Quite a high proportion of the frass of all the species studied contained the remains of Psocodea. The niche width of adults was broader than that of larvae except in C. quindecimguttata in which it was the opposite. The larval niches of the strict habitat specialists, C. quindecimguttata and S. vigintiguttata, were broader than those of the less habitat-specialists C. decemguttata and C. quatuordecimguttata. Adults of all the species studied showed relatively higher levels of food specialization than larvae, except for C. quindecimguttata. The results of this study indicate that ecological specialization is a complex phenomenon and habitat specialization does not imply food specialization.
Coccinella septempunctata was approximately 20% more reluctant to eat the eggs of Adalia bipunctata than the reverse. In addition, fourth instar larvae of C. septempunctata failed to complete their development on a diet of A. bipunctata eggs and only 30% of those of A. bipunctata completed their development on a diet of C. septempunctata eggs, and the survivors took nearly 2 times as long as those fed aphids. This is an indication that the costs of intraguild predation might outweigh the benefits.
The Multicoloured Asian Ladybird, Harmonia axyridis Pallas (Coleoptera: Coccinellidae) is known to thrive principally in shrubby and arboreal habitats. This study focuses on the occurrence of this exotic species and its seasonal abundance in various field crops. The abundance of adults, larvae and pupae of H. axyridis was evaluated over a three-year period, from 2009 to 2011, in four important agronomical crops (wheat, corn, broad bean and potato) in Belgium. From May to September, 48 1-m² quadrats were visually inspected in each of the fields sampled on several farms every seven days. H. axyridis colonized and reproduced in all of the four crops studied, with the largest numbers recorded in corn and broad bean crops. Larvae and adults of H. axyridis were recorded mainly in corn and to a much less extent in wheat and potato crops. From 2009 to 2011, the mean weekly abundance of H. ayxridis remained constant except in corn crops, where the recorded densities of all the immature stages and adults were higher in 2011 than in 2009. The population dynamics of aphids and H. axyridis are well described by a symmetric logistic function (S-shape) of cumulative population size. H. axyridis was not always recorded where aphids were abundant, e.g. aphids were abundant on wheat where no H. axyridis were recorded. H. axyridis start reproducing after the peak in aphid population, suggesting that H. axyridis is able to complete its development by feeding on alternative prey such as larvae and pupae of the same and other species of ladybird and other aphidophagous species. H. axyridis is often considered to be bivoltine but it only completes one generation per year in field crops. The second generation generally develops late in the season in other habitats., Axel Vandereycken ... [et al.]., and Obsahuje seznam literatury
Slunéčka (Coccinellidae) se brání jedovatými alkaloidy v hemolymfě. Zároveň inzerují svoji jedovatost rozmanitým výstražným zbarvením. V laboratorním pokusu se sýkorou koňadrou (Parus major) jsme ukázali, že odmítání slunéček hmyzožravými ptáky je alespoň zčásti naučené. Důležité je červené zbarvení, méně tečkovaný vzor., Ladybirds (Coccinellidae) possess poisonous defensive alkaloids in their haemolymph. They also employ variable warning colouration. In a laboratory experiment with an avian predator – the Great Tit (Parus major) – we have shown that avoidance of ladybirds was at least partly learned. The red colour itself is most important, the spotted pattern less important for the decision., and Oldřich Nedvěd, Petr Veselý.
The olfactory orientation of the aphidophagous ladybird Coccinella septempunctata L. was assessed in a Y-tube olfactometer and a choice arena. The response of the predator to 22 plants, aphid prey and conspecifics was tested. The ladybird was attracted to the odour of chopped Berberis vulgaris L. leaves, and of Tripleurospermum inodoratum (L.) Sch.-Bip. flowerheads, and males were attracted to females. Methanol extracts of B. vulgaris leaves were also attractive.
Empirical protocols for assessing the suitability of prey for aphidophagous coccinellids are examined and a modified scheme of categorization is presented. It is argued that prey suitability should be assessed independently for larval development and adult reproduction because of potentially divergent nutritional requirements between these life stages. A scheme is proposed for assessing prey suitability for larval development using conspecific eggs as a reference diet against which diets of various prey types can be compared both within and among coccinellid species. Among suitable prey (those that support ca. 100% survival of larvae to the adult stage), those that promote faster development and yield larger adults relative to a conspecific egg diet are considered "optimal" for larvae. Prey that yield viable adults with similar or reduced adult weight after a similar or extended period of development relative to a diet of conspecific eggs are classified as "adequate". Prey are "marginal" if they support the survival of some larvae, but significantly less than 100%. Supplementary water should be provided with any non-aphid diet (e.g. pollen and alternative sources of animal protein) given the potential for food-specific diet-drought stress interactions. For adults, suitable prey are classified as "adequate" if they support the production of viable eggs when fed as a monotypic diet, or "marginal" if they merely prolong adult life relative to a water source. Prey that comprise an optimal or adequate diet for both larval development and adult reproduction are termed "complete" and these can be indexed for relative suitability according to derived estimates of rm. Potential sources of error in diet evaluation studies are identified and discussed.
We surveyed ladybirds (Coleoptera: Coccinellidae) in 10 stands of Scots pine (Pinus sylvestris), all monoculture stands 5–100 years old, in western Slovakia, Central Europe, over two successive periods, October 2013 – March 2014 and October 2014 – March 2015. The winter in each period was exceptionally mild. Ladybirds were collected from the lower branches of pine trees using beating trays and were present in 61% of the 1040 samples (one sample containing ladybirds from 20 branches, 1 m long each). In total 3965 individuals of 20 species were recorded. Non-conifer dwelling species associated with broadleaved trees or herbaceous plants prevailed (45% of species), followed by conifer specialists (40%) and generalists (15%). Although 13 species were found at least in one winter month, December, January or February, only four of them, Exochomus quadripustulatus, Coccinella septempunctata, Harmonia axyridis and Hippodamia variegata, were recorded continually during both winters. The number of species, the abundance of all ladybirds and the abundance of dominant species (E. quadripustulatus, C. septempunctata and H. axyridis) decreased from late autumn towards winter and remained lowest during this most adverse time of the year for ladybirds. Overwintering species assemblages of ladybirds changed over time and varied with age of pine stand. Our results suggest that Scots pine in Central Europe supports species rich assemblages of ladybirds from late autumn to early spring and, being widely distributed, it could be suited to winter surveying of ladybirds at large spatial scales to reveal behavioural and ecological responses of species to changing weather or different climates.