Tamara Bianca Horn

Ecological interactions between phytophagous and predaceous mites in citrus agroecosystems in Taquari Valley, Rio Grande do Sul, Brazil

Abstract We examined the interaction between phytophagous and predaceous mites in Valencia orange (Citrus sinensis) orchards at different altitudes in the Taquari Valley, Rio Grande do Sul, Brazil. Mites were sampled monthly from February 2005 to January 2006 in three citrus agroecosystems: Arvorezinha, Encantado and Taquari. For each agroecosystem, twelve leaves were taken from each of ten citrus plants, plus ten fruits and leaves from five associated plants found in citrus orchards. Predaceous species considered important were Agistemus floridanus Gonzalez (Stigmaeidae), Euseius ho (De Leon) (Phytoseiidae) and Pronematus anconai Baker (Iolinidae). Other predators found were Iphiseiodes zuluagai Denmark & Muma (Phytoseiidae), in Taquari and Homeopronematus sp. (Iolinidae), Parapronematus sp. (Iolinidae), Neoseiulus tunus (DeLeon) (Phytoseiidae) and Typhlodromips cananeiensis Gondim Jr. & Moraes (Phytoseiidae), in Encantado. The most frequent phytophagous mites were Brevipalpus phoenicis (Geijskes) (Tenuipalpidae), Lorryia formosa Cooreman (Tydeidae), Lorryia sp. (Tydeidae), Tegolophus brunneus Flechtmann (Eriophyidae) and Tetranychus mexicanus (McGregor) (Tetranychidae). Other phytophages were Eutetranychus banksi (McGregor) (Tetranychidae) in Taquari and Phyllocoptruta oleivora (Ashmead) (Eriophyidae) in Arvorezinha. The predator A. floridanus had the strongest correlation to the presence of common phytophagous mites, followed by P. anconai that seemed to be associated with eriophyid and tetranychid mites. The least number of predators occurred in Arvorezinha, where mowing and phytosanitary treatments were frequent. The associated plants Thelypteris dentata (Forssk.) E.P. St. John and Solidago chilensis Meyen had the largest abundance of predatory mites. However, Ageratum conyzoides L. had the highest diversity of predatory mites.

Two new genera of pyroglyphid mites, Tuccioglyphus and Marioglyphus , with a key to genera of the World (Acari: Pyroglyphidae)

We describe Tuccioglyphus setosus gen. et sp. nov. from the litter of commercially reared laying hens as well as wild birds in Brazil. The new genus Tuccioglyphus presents a mixture of character states between the two conventional subfamilies, Pyroglyphinae and Dermatophagoidinae. Based on this new unusual genus, we discuss character states delimiting these and other major subfamilies of the house dust mite family, Pyroglyphidae, as well as its most important and species-rich genus Dermatophagoides. An additional new genus, Marioglyphus gen. n., is proposed for Hughesiella valerioi Vargas and Smiley. Both Tuccioglyphus and Marioglyphus are related to the genus Hughesiella. A key to pyroglyphid genera of the World is presented.

Development of Cheyletus malaccensis (Acari: Cheyletidae) feeding on mite species found in commercial poultry systems: Megninia ginglymura (Acari: Analgidae) and Tyrophagus putrescentiae (Acari: Acaridae)

Abstract Intensive egg production affects the welfare of confined laying hens, which increases the risk of epidemics. Ectoparasitic hematophagous mites and saprophagous feather mites cause low productivity and decreased egg quality. This study aimed to compare the biology of Cheyletus malaccensis (Oudemans) (Prostigmata: Cheyletidae) feeding on the prey Megninia ginglymura (Mégnin) (Astigmata: Analgidae) and Tyrophagus putrescentiae (Schrank) (Astigmata: Acaridae) in order to support the potential use of this predator in biological control strategies in the poultry industry. The study started with 30 eggs of C. malaccensis, isolated in experimental units, which developed into their different stages while feeding on the feather mite M. ginglymura and the stored product mite T. putrescentiae at 25±1°C, 80±5% relative humidity and 12-hour photoperiod. Immature stages were evaluated three times a day and the adult stage once a day. Adult females were unmated. Cheyletus malaccensis feeding on M. ginglymura resulted in a higher fertility rate, with 310.7±45.8 eggs/female, than with T. putrescentiae as prey, with 32.7±4.5 eggs/female. Furthermore, the oviposition period was higher feeding on M. ginglymura, 53.0±6.3 days, than on T. putrescentiae, 12.6±1.9 days. The net reproductive rate (Ro), the innate capacity for increase (rm), the mean generation time (T) and the finite rate of increase (λ) were higher for the generation fed on M. ginglymura. Cheyletus malaccensis is a likely natural enemy of M. ginglymura, and it is able to develop and reproduce while feeding exclusively on it.