Aphidophagous lady beetles rely on multiple sources of food in their environment. Alfalfa fields provide both aphids and many alternate foods, such as other arthropod prey, pollen, and fungi. Alfalfa fields (Medicago sativa L.) in Utah have low aphid densities, which may require lady beetles to consume alternative sources of food. Many methods can be used to determine these diets; frass analysis is used here to compare the diets of the introduced species Coccinella septempunctata L. with two native species, C. transversoguttata richardsoni Brown and Hippodamia convergens Guérin-Méneville, that occur in the Utah alfalfa habitat. In initial laboratory experiments to examine the feasibility of frass analysis, 48 hours at 20oC was sufficient time for adult lady beetles to pass prey cuticle through their guts. When consumed by these adults, pea aphids (Acyrthosiphon pisum [Harris]), alfalfa weevil larvae (Hypera postica [Gyllenhall]), and C. septempunctata larvae produced distinctive fragments in the frass. Such fragments could also be distinguished in frass collected in a field experiment in which aphid densities in plots of alfalfa were manipulated. Furthermore, additional consumed foods could be distinguished in the field experiment, including pollen, fungi, and other types of arthropods. Frass analysis demonstrated higher use of aphid prey by C. septempunctata adults collected from high versus low aphid density plots during the field experiment. Use of other types of prey, such as alfalfa weevil larvae, other arthropods, pollen and fungi, was similar between plots with high and low aphid densities. A field census was performed over two years to track the diets of the three species of lady beetles during the first crop of alfalfa, when two sources of prey in particular were present, aphids and alfalfa weevil larvae. Comparisons of diets revealed that the three species utilized different types of prey to similar degree during both years. In general, however, higher percentages of C. septempunctata adults were found to have consumed aphids and weevils during both years. Also, C. septempunctata was found to produce more frass and consume larger quantities of prey than either native species during the second year.

Submitted by (edna.saturno@ufrpe.br) on 2016-11-28T16:17:54Z No. of bitstreams: 1 Paulo Roberto Ramos Barbosa.pdf: 763274 bytes, checksum: d1db37522ca460481761084d57a5e771 (MD5) / Made available in DSpace on 2016-11-28T16:17:54Z (GMT). No. of bitstreams: 1 Paulo Roberto Ramos Barbosa.pdf: 763274 bytes, checksum: d1db37522ca460481761084d57a5e771 (MD5) Previous issue date: 2012-07-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The lady beetles are an outstand predatory group among the natural enemies applied as biological control agents against arthropod pests. The lady beetle Tenuisvalvae notata (Mulsant), is a predator of Pseudococcidae and recently was found on cotton plants infested with Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae) and on prickly pear infested with the false red cochineal Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae), both in the Semiarid of Pernambuco. Thus, the performance of T. notata preying upon D. opuntiae, F. virgata and eggs of Anagasta kuehniella Zeller (Lepidoptera: Pyralidae) was studied. Further, the predation and reproduction when subjected to different condition of F. virgata availability and scarcity was also investigated. Although naturally collected on colonies of false red cocheneal from prickly pear, T. notata nor developed neither reproduced feeding exclusively on this pest. Likewise, eggs of A. kuehniella did not furnish development and reproduction of T. notata. On the other hand, F. virgata of different stages was successfully used as prey by larvae and adult of T. notata. Adult females of T. notata exhibited a type III functional response preying upon 1st-insar nymph of F. virgata and type II functional response when preying upon 3rd-instar and adults. Based on the functional response it is estimated predation rate of 157.8 1st-instar nymphs, 3.6 3rd-instar nymphs, and 2.2 females of F. virgata per day. Feeding on F. virgata 3rd-instar nymphs resulted in 1.23 eggs produced per each mealybug nymph consumed. However, female lady beetles subjected to prey scarcity exhibited switch on reproductive and survival output already with one day of feeding interval depicting a strong relationship of consumption, reproduction and survivorship between T. notata and F. virgata. The high performance of T. notata preying upon F. virgata and her functional response, in addition the balance of reproduction and survival showed when subjected to prey scarcity, portray T. notata as a feasible predator to control of F. virgata. / Os coccinelídeos predadores se destacam como um dos mais importantes grupos de inimigos naturais empregados no controle biológico de artrópodes pragas. A joaninha Tenuisvalvae notata (Mulsant), espécie nativa da América do sul e predadora de Pseudococcidae, foi recentemente constatada no Semiárido de Pernambuco associada a plantas de algodão infestadas com a cochonilha de listra, Ferrisia virgata Cockerell (Hemiptera: Pseudococcidae), e em palma forrageira infestada com a falsa cochonilha do carmim, Dactylopius opuntiae Cockerell (Hemiptera: Dactylopiidae). Assim, este trabalho avaliou o desempenho de T. notata sobre D. opuntiae, F. virgata e em ovos de Anagasta kuehniella Zeller (Lepidoptera: Pyralidae), bem como determinou seu potencial de predação e reprodução em diferentes condições de disponibilidade da cochonilha F. virgata. Mesmo sendo coletada em colônias da falsa cochonilha do carmim, T. notata não se desenvolveu e nem reproduziu ao predar exclusivamente esta cochonilha. Da mesma forma, ovos de A. kuehniella não foram adequados como alimento para T. notata. Por outro lado, F. virgata em diferentes estágios de desenvolvimento mostrou-se adequada como presa de T. notata, sendo consumida tanto por larvas quanto por adultos desta joaninha. Fêmeas de T. notata exibiram resposta funcional tipo III predando F. virgata de primeiro instar, e tipo II para ninfas de terceiro instar e fêmeas adultas apresentando um consumo estimado de 157,8 ninfas neonatas, 3,6 ninfas de terceiro instar ou 2,2 fêmeas adultas de F. virgata por dia. A alimentação diária em ninfas de terceiro instar de F. virgata resulta na média de 1,23 ovos produzidos para cada ninfa da cochonilha consumida. No entanto, quando as joaninhas são submetidas a diferentes intervalos de oferta de presa, observa-se influência na produção de ovos e sobrevivência já com um dia de intervalo de alimentação, caracterizando uma estreita relação de consumo, reprodução e sobrevivência para a associação T. notata e F. virgata. O desempenho de T. notata predando F. virgata e sua resposta funcional, somado ao balanço reprodutivo e sobrevivência apresentados sob condição de escassez desta presa, demonstra que T. notata é um predador em potencial para o controle de F. virgata.