Chilocorus kuwanae Silvestri is an effective predator of Unaspis euonymi (Comstock), a scale insect harmful to spindle trees (Euonymus europeus L. and E. japonicus Thumb). The feeding behaviour was studied on wild adults, collected from spindle trees in the Botanic Garden of Perugia University, and fed on overwintering U. euonymi females. The insects were exposed to gradually changing constant temperatures (13°-->10°-->8°-->6°-->4°-->2°-->13°-->15°C) for a ten day period at each temperature. C. kuwanae adults preyed on the scale also at low temperatures. The number of scales eaten decreased with decreasing temperatures from the initial 13°C to 4°C, and at 2°C the trophic activity of C. kuwanae adults almost stopped although they made brief walks in the petri dishes. At all tested temperatures the ladybirds made holes in or lifted the scale cover and preyed on the female. Sometimes they lifted the scale cover , but did not prey on these U. euonymi females which were destined to die from cold. As the temperature dropped from 13°C to 4°C, the number of females eaten by ladybird males and females did not differ statistically. When the temperature was raised to 13°C and 15°C, the ladybirds resumed feeding. Large differences were recorded between sexes, with females showing a much higher feeding activity than males. Scale cover lifting was most frequent at the beginning of the experiment and then decreased with diminishing temperatures, although no significant difference was recorded among temperatures within the range from 10°C to 4°C. The threshold for trophic activity can be taken as 2°C since we noted that a few (12%) individuals on one day showed predatory activity. At 13°C and 15°C lifting activity rose again but remained at a lower level than at the initial exposure to 13°C. There was no significant difference in activity at 13 and 15°C upon raising the temperature. As for total number of U. euonymi damaged by C. kuwanae the trend in damage revealed the same pattern as for number of scales eaten. At the final exposure to 15°C, 60% of C. kuwanae females laid eggs. Our data demonstrate that C. kuwanae can reduce U. euonymi populations in a submediterranean environment even in winter when the range of temperatures is similar to that tested in this experiment.
1_Intraguild predation (IGP) and cannibalism occur in the field and could affect the dominance structure of guilds of coccinellid species. The exotic biological control agent Harmonia axyridis (Pallas) (Coleoptera: Coccinellidae) is now well established in most areas of Northern and Central Italy, but it is unclear what effect this species could have on native dominant and non-dominant coccinellids with which it co-occurs. In order to predict the trophic interactions in coccinellid guilds and the likely effect of H. axyridis, the incidence of IGP and cannibalism among the following six species were evaluated under laboratory conditions: H. axyridis, three native dominant species, Adalia bipunctata (L.), Oenopia conglobata (L.) and Coccinella septempunctata L. and two native non-dominant species, Platynaspis luteorubra (Goeze) and Scymnus apetzi (Mulsant). Unfed and fed fourth instar larvae of the above species were paired in an experimental arena and the incidence of predation recorded over a period of 24 h. In absence of aphids, the survival probabilities (SP) of A. bipunctata and O. conglobata were lowest when paired with either C. septempunctata or H. axyridis (< 0.20 SP after 24 h). The SP of C. septempunctata was similar if paired with either a conspecific larva or H. axyridis (< 0.34 SP after 24 h) and that of H. axyridis was reduced similarly if paired with either a conspecific larva or C. septempunctata (> 0.71 SP after 24 h). The SP of P. luteorubra was lower when paired with A. bipunctata and C. septempunctata (< 0.07 SP after 24 h) than with other species and that of S. apetzi was greatly reduced when paired with all the dominant and exotic species (< 0.27 SP after 24h)., 2_In presence of aphids no predatory events occurred in most combinations. H. axyridis acted as a strong predator of native dominant and non-dominant coccinellids when the aphids are scarce. We did not find any evidence, however, that the incidence of IGP among exotic and native species is higher than either IGP or cannibalism in native species. The likelihood of IGP occurring in the field is discussed., Gabriele Rondoni, Andrea Onofri, Carlo Ricci., and Obsahuje seznam literatury
The laboulbenialean fungi occur throughout the world and are closely associated with a range of arthropods, including many coleopteran hosts. Throughout the summer of 2004, coccinellids were collected from a Bluegrass savanna woodland ecosystem, dominated by blue ash Fraxinus quadrangulata and Chinkapin Oak Quercus muehlenbergii, and the adults were examined for the presence of Hesperomyces virescens using binocular and scanning electron microscopy. Over 80% of adult Harmonia axyridis, a species previously reported as having a persistent association with the fungus, were infected. No significant differences were observed in incidence on male and female hosts, however, the distribution of fungus differed between sexes. Female H. axyridis had a greater percentage of infection on their elytron compared to other parts of their body whilst male infection was concentrated around their elytra, legs and abdomen. Although infection rates were significantly lower, we report, for the first time, the presence of this fungus on the hosts Cycloneda munda, Brachiacantha quadripunctata and Psyllobora vigintimaculata. This is the first study documenting the incidence of this insect-associated fungus with these native coccinellids of North America. In the samples collected from the Bluegrass savanna, two species (Coleomegilla maculata and Hyperaspis signata) were not infected by this fungus.
The aim of this study was to clarify the diet of Ceratomegilla notata (Laicharting), a common species in different mountain habitats of the Palearctic region. In Italy it is found only in alpine ecosystems between 800-1700 m. In these areas, up to 1200 m, various crops (e.g., maize, potatoes) are present. The high meadows are cut for hay. From 2002 to 2003 investigations on the foraging behaviour of this ladybird were carried out in mountain habitats (six near Villabassa, in Bolzano province, and six near Soraga, in Trento province) and in the "Paradisia" Botanic Garden (Gran Paradiso National Park). C. notata adults and larvae were found on the flowering plants, especially those infested by aphids. The study of their diet was done taking random D-Vac samples of 20 adults and 20 larvae/habitat every 15 days, between July and September. The influence of the haymaking on C. notata populations was also evaluated.
In agricultural fields the ladybirds prey on Rhopalosiphum maidis (Fitch), R. padi (L.) on maize and on Acyrthosiphon pisum (Harris) and Therioaphis luteola (Born.) on Trifolium pratense L. In the natural pastures, adults and larvae feed on Cavariella theobaldi G. & B. found on Heracleum sphondylium (Umbelliferae), Sitobion avenae L. on Avena sativa L., Megoura viciae (B.) and A. pisum on Vicia cracca L., Uroleucon jaceae (L.) on Cirsium arvense Scop., U. cichorii (Koch) on Hypochaeris radicata L. and Macrosiphum weberi Born. on Scabiosa sp. A study of the gut contents revealed the presence of aphids, Umbelliferae pollens and spores of fungi (e.g., Alternaria spp., Helminthosporium spp., Puccinia spp.). Statistically significant associations between different food sources were more frequent for adults than for larvae in both 2002 and 2003. Thrips are an important prey of this ladybird in the absence of aphids. C. notata is an important aphidophagous species in Alpine habitats.