Biological aspects of Harmonia axyridis in comparison with Cycloneda sanguinea and Hippodamia convergens

The objective of this work was to evaluate the development, survival, reproductive capacity, and longevity of the Asian ladybug Harmonia axyridis in comparison with Cycloneda sanguinea and Hippodamia convergens. Coccinellid larvae and adults were fed daily with Schizaphis graminum. Ten couples of each species were isolated for evaluation of the adult phase. The duration of the larval stage of H. axyridis is the longest (10.2 days) and its adults are the heaviest (29.7 mg) compared with C. sanguinea and H. convergens. The three species showed similar percentages of survival during the developmental stages. An average of 82% of C. sanguinea, H. axyridis, and H. convergens larvae reached adulthood, which indicates that temperature (25°C) and the offered prey are favorable to coccinellid development. Harmonia axyridis produces a higher total number of eggs per female (1,029.2) than the other evaluated species. However, H. axyridis, which lives for an average of 147.2 days, does not show a significantly greater longevity than C. sanguinea (87.2 days) and H. convergens (134.3 days).O objetivo deste trabalho foi avaliar o desenvolvimento, a sobrevivência, a capacidade reprodutiva e a longevidade da joaninha-asiática Harmonia axyridis em comparação a Cycloneda sanguinea e Hippodamia convergens. Larvas e adultos dos coccinelídeos foram alimentados diariamente com Schizaphis graminum. Isolaram-se dez casais de cada espécie para as avaliações na fase adulta. A duração da fase larval de H. axyridis é maior (10,2 dias) e os adultos são mais pesados (29,7 mg) em comparação a C. sanguinea e H. convergens. As três espécies apresentaram percentagem de sobrevivência similar durante os estádios de desenvolvimento. Em média, 82% das larvas de C. sanguinea, H. axyridis e H. convergens atingiram a fase adulta, o que indica que a temperatura (25°C) e a presa oferecida foram favoráveis ao desenvolvimento dos coccinelídeos. Harmonia axyridis produz maior número total de ovos por fêmea (1.029,2) do que as demais espécies avaliadas. No entanto, H. axyridis, que vive, em média, 147,2 dias, não apresenta longevidade significativamente maior que C. sanguinea (87,2 dias) e H. convergens (134,3 dias).Universidade Estadual Paulista Faculdade de Ciências Agrárias e Veterinárias Departmento de FitossanidadeAgência Paulista de Tecnologia dos AgronegóciosUniversidade Estadual Paulista Faculdade de Ciências Agrárias e Veterinárias Departmento de Fitossanidad

Effect of temperature on development, growth and feeding of Coccinella septempunctata and Hippodamia convergens reared on the tobacco aphid, Myzus persicae nicotianae

Preimaginal development, mortality, aphid consumption rate, and size and weight upon reaching the adult stage of the aphidophagous coccinellids Hippodamia convergens Guerin-Meneville and Coccinella septempunctata L. collected from Karditsa, central Greece, were examined at four constant temperatures ( 14, 17, 20 and 23 degrees C) and L16: D8. The coccinellids fed on the tobacco aphid, Myzus persicae nicotianae Blackman. Egg, larval and pupal mortality was highest at 14 degrees C reaching 85.0, 73.8 and 29.4% in H. convergens and 49.3, 75.4 and 58.8% in C. septempunctata, respectively. Total preimaginal development ranged from 57.2 to 70.4 days at 14 degrees C, and to 16.9 and 22.1 days at 23 degrees C in H. convergens and C. septempunctata, respectively. Heavier and larger adults of H. convergens were obtained at 17 and 20 degrees C. In C. septempunctata temperature did not affect adult weight while the lowest size was observed at 14 and 17 degrees C. Day-degrees requirements for preimaginal development in H. corvengens were 212.9 above a developmental threshold of 11.0 degrees C. The corresponding values for C. septempunctata were 281.5 and 10.7 degrees C. In H. convergens total and daily aphid consumption ranged from 46.8 aphids at 14 degrees C to 85.0 aphids at 23 degrees C and from 1.5 aphids at 14 degrees C to 9.2 aphids at 23 degrees C, respectively. The corresponding values for C. septempunctata were 112.0 and 2.7 at 14 degrees C and 157.7 and 12.4 at 23 degrees C. The results show the high potential of both predators as biological control agents against the tobacco aphid. The knowledge obtained could be essential for their appropriate use and for the improvement of mass rearing systems