ABSTRACT
The two spotted spider mite, Tetranychus urticae Koch, is a nontarget herbivore of Bt-cotton, but acquires and accumulates higher levels of Cry toxin than that expressed by transgenic plants. This work investigated the development and reproduction of T. urticae and of the predator Phytoseiulus macropilis Banks, during three successive generations looking for potential nontarget effect. In addition, behavioral studies on feeding preference, oviposition, and predation were carried out on Bt and non-Bt cottons. The development and reproduction of T. urticae and P. macropilis was conducted using leaf discs of Bt and non-Bt cottons. Arena containing leaf discs from both cotton types connected by a slide coverslip were also used in the behavioral studies. Averages of the three generations showed that the Bt-cotton does not affect the development, survival of immature stages, and reproductive output of T. urticae and of the predator P. macropilis. Furthermore, the preference for feeding and oviposition of T. urticae and P. macropilis were similar on both cotton types. In addition, P. macropilis exhibited similar predatory behavior on T. urticae fed on both cotton types. Levels of Cry1Ac toxin in T. urticae was 3.97 times greater than that found in the Bt-cotton plants as determined using a ELISA test. Despite of the amount of toxin acquired by the prey (T. urticae), no detectable levels of Cry1Ac were found in the predatory mite P. macropilis.
Subject(s)
Animals , Acari/physiology , Gossypium/parasitology , Plants, Genetically Modified/parasitology , Tetranychidae/physiology , Behavior, Animal , Gossypium/geneticsABSTRACT
Oligonychus ilicis (McGregor) is among those mite species that can cause damage to coffee plants (Coffea spp.). Species of Phytoseiidae acari are considered the most important and studied predatory mites. The objective of this study was to evaluate the effects of the webbing produced by O.ilicis on its predation by females of the phytoseiids Iphiseiodes zuluagai Denmark & Muma, Euseius citrifolius Denmark & Muma and Amblyseius herbicolus (Chant). Four bioassays were conducted, with three treatments and ten replicates. Each replicate consisted of 25 O.ilicis per experimental unit (a leaf disc of Coffea arabica) according to the tested developmental stage, in independent experiments. To spin the web, 15 adult females were put on each experimental unit for 24h; females were then removed, leaving only the web, and predators and prey to be tested were introduced. Predation was assessed after 24h. In the presence of webbing, the consumption of eggs, larvae and nymphs by I.zuluagai and eggs and larvae by E.citrifolius was lower. For A.herbicolus, egg predation was lower, but larval predation did not vary significantly and predation of nymphs and adults was higher in the presence of webbing. Predators as a whole were more efficient consuming larvae regardless of the presence of webbing. Considering the stages of O.ilicis altogether, webbing reduced the predation potential of I.zuluagai and E. citrifolius, but not of A. herbicolus.
Subject(s)
Animals , Female , Acari/physiology , Predatory Behavior , Tetranychidae , Coffee/parasitologyABSTRACT
O Núcleo de Reabilitação da Fauna Silvestre e Centro de Triagem de Animais Silvestres da Universidade Federal de Pelotas - RS atendeu dois filhotes de Megascops choliba (corujinha-do-mato) (Strigiformes - Strigidae) e dois de Pitangus sulphuratus (bem-te-vi) (Passeriformes - Tyrannidae) intensamente parasitados por ácaros, em maio de 2005 e dezembro de 2006, respectivamente. Os filhotes e o ninho de P. sulphuratus foram recolhidos na zona urbana da cidade de Pelotas - RS após forte temporal. Os ácaros foram removidos, colocados em álcool 70 por cento e levados ao laboratório de parasitologia para identificação. Os espécimes foram clarificados em lactofenol, montados em meio de Hoyer e identificados como Ornithonyssus bursa (Acari - Macronyssidae). Registra-se Megascops choliba e Pitangus sulphuratus como hospedeiros de Ornithonyssus bursa, no Rio Grande do Sul, Brasil.
The Center for Rehabilitation of Wildlife and Center for Selection of Wild Animal of the Federal University of Pelotas has attended two nestlings of Megascops choliba (tropical screech-owl) (Strigiformes - Strigidae) and two of Pitangus sulphuratus (great kiskadee) (Passeriformes - Tyrannidae) heavily parasitized by mites, in May 2005 and December 2006, respectively. The nestlings and the nest of P. sulphuratus were collected in the Pelotas urban area after severe storms. The mites were removed, clarified in lactofenol, permanently mounted in Hoyer's medium and identified as Ornithonyssus bursa (Acari - Macronyssidae). Megascops choliba and Pitangus sulphuratus are reported as host of Ornithonyssus bursa in Rio Grande do Sul State, Brazil.
Subject(s)
Animals , Acari/physiology , Passeriformes/parasitology , Strigiformes/parasitology , Animals, Newborn , BrazilABSTRACT
This study evaluated the effectiveness of a neem extract-based product to control O. sylviarum infestations in commercial laying hens. The birds were divided in 3 groups, which received 2, 3, or 4 applications of the product at 7 day intervals. The results obtained allow the conclusion that the neem extract at 2" percent is effective to control infestations by O. sylviarum, and at least 3 sprays of the product are required weekly for an effective control of the parasite.
O presente trabalho teve por objetivo avaliar a eficácia de um produto à base de extrato de nim, no controle da infestação por O. sylviarum em poedeiras comerciais. O experimento foi realizado observando-se a eficácia do extrato de nim a 2 por cento após duas, três e quatro aplicações com intervalo de sete dias. Os resultados obtidos permitem concluir que o extrato de nim a 2 por cento é efetivo no controle da infestação por O. sylviarum, sendo necessárias pelo menos três pulverizações semanais do produto para que haja o controle efetivo do parasito.
Subject(s)
Animals , Azadirachta , Acari/physiology , Chickens/parasitology , Plant Extracts , Poultry Diseases/parasitology , Communicable Disease Control/methodsABSTRACT
O ácaro Polyphagotarsonemus latus (Banks) constitui uma das principais pragas da videira no Submédio do Vale do São Francisco. Sendo assim, o objetivo deste trabalho foi estudar a biologia, determinar as exigências térmicas e a tabela de vida de fertilidade de P. latus em videira (Vitis vinifera L.) cv. Itália. Foram utilizadas câmaras climatizadas (BOD), ajustadas para as temperaturas de 18, 22, 25, 28 e 32°C, umidade relativa de 65 ± 10 por cento e fotofase de 12h. O período ovo-adulto foi de 3,4 e de 6,8 dias para machos e de 3,5 e de 7,4 dias para fêmeas, respectivamente a 32 e 18°C. Nas temperaturas de 18, 25 e 32°C cada fêmea depositou, respectivamente, 16,5; 44,3 e 13,3 ovos. Os estágios de ovo, larva e pupa e o período ovo-adulto apresentaram, respectivamente, limiar térmico inferior de 11,23; 9,45; 12,19 e 9,71°C e constantes térmicas de 28,51; 14,59; 8,33 e 62,73 graus-dia. A duração média da geração (T) foi igual a 25,6; 10,8 e 8,2 dias, respectivamente, nas temperaturas de 18, 25 e 32°C. A taxa líquida de reprodução (R0) foi maior na temperatura de 25°C, correspondendo a um aumento de 30,12 vezes a cada geração. A taxa intrínseca de crescimento populacional (r m) foi de 0,10 (18°C); 0,31 (25°C) e 0,12 (32°C) e a razão finita de aumento populacional (lambda) 1,10 (18°C); 1,36 (25°C) e 1,13 (32°C). De acordo com as normais térmicas, P. latus pode desenvolver 95 e 99 gerações/ano, respectivamente, para os municípios de Petrolina, PE e Juazeiro, BA.