Mite fauna (Acari) associated with the poultry industry in different laying hen management systems in Southern Brazil: a species key

This study is based on results from a large project on the mite diversity in commercial laying hen systems in Brazil. It aims to identify potential biocontrol agents amongst mites present in poultry farms, with a focus on one feather mite pest Megninia ginglymura. A secondary goal is to provide an operational identification tool to help the development of biological control in poultry farms. Sampling was conducted from August 2013 to August 2014, with 43 sampling events, in three different laying hen management systems. We used traps, laying hen feathers, and abandoned wild bird nests to collect the mites. A total of 38,862 mites belonging to 23 families and 39 species were found, including 17 species exclusively found in traps, six in wild bird nests, and one in feathers. The most abundant and frequent ectoparasitic species was M. ginglymura (76.3%; observed in all management systems). Amongst other mites, Tydeidae showed the highest richness with five species (Brachytydeus argentinensis (Baker, 1970), Brachytydeus australensis (Baker, 1970), Brachytydeus obnoxia (Kuznetzov and Zapletina, 1972), Brachytydeus oregonensis (Baker, 1970), and Brachytydeus tuttlei (Baker, 1965)), followed by Cheyletidae with four species (Chelacheles bipanus Summers and Price, 1970, Cheyletus eruditus (Schrank, 1781), Cheyletus malaccensis (Oudemans, 1903), and Cheletomimus (Hemicheyletia) wellsi (Baker, 1949)). Potential predatory species for biological control were C. malaccensis (9.4%), Typhlodromus transvaalensis (Nesbitt, 1951) (0.8%), Blattisocius keegani (Fox, 1947) (0.7%), and Blattisocius dentriticus (Berlese, 1918) (0.4%). A dichotomous key is provided to identify 48 species dwelling in Brazilian layer farms.

Avaliação da presença de ácaros em cereais armazenados na grande São Paulo

O exame microscópico de 160 amostras de cereais (arroz, feijão, trigo, milho, a veia, ervilha e sorgo), 40% fornecidas pelo Instituto Adolfo Lutz e provenientes de distribuidores como COBAL, CIBRAZEM, PETROPACK, CEAGESP, DECOM e do 2º Exército, e 60% adquiridas em mercadinhos e armazéns na Grande São Paulo, feito no ato e após 42 dias de incubação a 25°C e 70% UR revelou que 49% das amostras apresentavam populações de ácaros primários de alimentos armazenados. Destas, 48% revelaram a presença de Tyrophagus putrescentiae (Schrank), 17,5% Aleuroglyphus ovatus (Troupeau), 6,8% Glycyphagus domesticus (DeGeer), 4,37% Chortoglyphus arcuatus (Troupeau), 3,8% Suidasia pontifica Oudemans, 3,12% Blomia tropicallis Bronswijck, Cook & Oshima, 1,25% Histiostoma sp. e Dermatophagoides pteronyssinus (Trouessart). Ácaros secundários também foram encontra dos destacando-se Tarsonemus sp., Cheyletus malaccensis Oudemans e Blattisocius dentriticus (Berlese), entre outros. As amostras originárias dos grandes distribuidores apresentavam bem menos ácaros do que aquelas dos pequenos armazéns onde a rotatividade de estoque é bem menor. O resultado positivo para ácaros de amostras mantidas em incubador por 42 dias quando seu exame no ato não os revelou, mostra que o simples exame de uma amostra de cereal num dado momento não exclui a hipótese dele estar contaminado por ovos de ácaros primários de alimentos. Dentre os insetos, o mais frequente foi o gorgulho Sitophilus orizae (L.) presente em amostras de arroz, milho e trigo.

Biological models of two acarine predators of the grain mite, Acarus siro L.

A biological model of predation was developed using granular food held in closely packed screen trays to propagate the grain mite, Acarus Siro L., and two of its predators, Blattisocius dentriticus (Berl.) and Cheyletus eruditus (Schrank). Both predators limited prey abundance. Cannibalism among predators, particularly C. eruditus, was an important factor in ensuring the survival of the prey and predator populations. Cheyletus eruditus eliminated B. dentriticus when the two species were propagated in the same experimental universe. Cyclicity and dispersion of the interacting species appeared to result more from the initial age structure and from dispersion of the prey than from predator attack. A population model was used to assess the relative importance of the population components of A. siro and C. eruditus in the simplified predator–prey interactions.

AN ACARINE PREDATOR–PREY POPULATION INFESTING STORED PRODUCTS

Populations of the stored product mite Tyrophagus putrescentiae (Schrank) and its predator Blattisocius dentriticus (Berl.) were propagated in two experimental universes. Although the predator determined the size of the prey populations, the densities of both species fluctuated with peaks of abundance occurring every 6 to 8 weeks. A number of factors modified, to some extent, the role of "predator searching" as a mechanism controlling both the average densities and fluctuations in abundance of the two species. With large fluctuations in the abundance of the prey there was a pronounced cycle in the age structure of the predator and prey populations. The larger stages of the prey were largely immune to attack by the predator. Individuals of the predator developed to about one-half their normal size when the prey were scarce. The combination of immune stages of the prey and adjustment of predators to scarcity of prey ensured the coexistence of the predator–prey system. Contamination of experimental populations by psocids was one of the major hazards in rearing the populations for extended periods.