Morphological study of the thorax of the five nymphal instars of Triatoma arthurneivai Lent & Martins (Hemiptera, Reduviidae, Triatominae)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Susceptibilidade de Rhodnius neglectus, Rhodnius robustus e Triatoma infestans (Hemiptera, Reduviidae, Triatominae) à infecção por duas cepas de Trypanosoma cruzi (Kinetoplastidae, Trypanosomatidae) utilizando xenodiagnóstico artificial

A susceptibilidade de ninfas de 3º estádio de Rhodnius neglectus, R. robustus e Triatoma infestans às cepas Y e AMJM de Trypanosoma cruzi foi verificada utilizando xenodiagnóstico artificial. Para a leitura do xenodiagnóstico, as fezes dos triatomíneos foram examinadas a cada dois dias, a partir do 5º até o 31º dia pós infecção, pela técnica de compressão abdominal. Os resultados mostraram diferenças na susceptibilidade dos triatomíneos para as duas cepas estudadas e o período ótimo de leitura variou do 11º ao 19º dias para a cepa Y e do 11º ao 15º dias para a cepa AMJM. Também, pôde-se concluir que para a cepa Y, as três espécies de triatomíneos demonstraram boa susceptibilidade, enquanto para a cepa AMJM, a melhor susceptibilidade foi observada com R. neglectus, seguida pelo T. infestans e R. robustus.

Distribution of Rickettsia rickettsii in ovary cells of Rhipicephalus sanguineus (Latreille1806) (Acari: Ixodidae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Nymphal development, lipid content, growth and weight gain of Nezara viridula (L.) (Heteroptera: Pentatomidae) fed on soybean genotypes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Developmental biology, polymorphism and ecological aspects of Stiretrus decemguttatus (Hemiptera, Pentatomidae), an important predator of cassidine beetles

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito do cultivo do mamoeiro (Carica papaya L.) em ambiente protegido sobre a ocorrência de ácaros fitófagos e moscas-brancas

O efeito do cultivo do mamoeiro em ambiente protegido foi estudado em três condições: sem cobertura e em dois telados construídos com tela de propileno branca, com malhas de 2 x 2 mm e 2 x 1 mm. Nessa área foram feitas avaliações na cultivar Baixinho de Santa Amália, contando-se o número de plantas com sintomas de ataque recente, para o ácaro branco Polyphagotarsonemus latus, com sintomas e presença de ácaros, para o ácaro rajado Tetranychus urticae e com presença de adultos ou ninfas nas folhas, no caso das moscas-brancas Trialeurodes sp., Bemisia tabaci biótipo B e uma terceira espécie não identificada. Para moscas-brancas, também foram realizadas contagens de ninfas e exúvias em laboratório. O cultivo em ambiente protegido favoreceu a sobrevivência e o desenvolvimento populacional das espécies estudadas, sendo que algumas possíveis causas são discutidas no texto. Considerando-se que o cultivo protegido pode ser uma boa alternativa para o controle de viroses, como o mosaico do mamoeiro, problema limitante para a cultura, estratégias de manejo de pragas nesses ambientes devem ser desenvolvidas, para viabilizar o seu uso.

Acquired resistance of horses to Amblyomma cajennense (Fabricius, 1787) ticks

Acquired immunity of horses to larvae, nymphs and adults of the Amblyomma cajennense tick was evaluated through three consecutive experimental infestations of tick-bite naive hosts. Data from these infestations were compared to those from field-sensitized horses and donkeys. It was observed that tick-bite naive horses developed a low level of resistance after two infestations as shown by a significant decrease in larval yield and a tendency for lower engorged weight of nymphs during third infestation. Ticks fed on field-sensitized horses had a similar biological performance to that observed on the third infestation of tick-bite naive horses but the mean engorged nymph weight was significantly lower than that of the first infestation from tick-bite naive horses. Donkeys presented the strongest resistance with significantly lower engorged weights of all instars and of the egg mass compared to the first infestation of tick-bite naive horses. Donkeys also displayed a significantly higher resistance than field-sensitized horses as demonstrated by significantly lower egg mass weights. Overall these results indicate that donkeys but not horses maintain a strong resistance to A. cajennense ticks. The importance of these findings in relation to vectoring of tick-borne diseases is discussed. (C) 2003 Elsevier B.V. All rights reserved.

Nymphs in foraging populations of Coptotermes gestroi (Isoptera: Rhinotermitidae)

Food searching activity by subterranean termites involves workers, soldiers and nymphs. The present study was carried out for elucidating aspects of nymph foraging behavior in Brazil where the species Coptotermes gestroi (Wasmann, 1896) is exotic. Monitoring was conducted through making regular collections from seven different colonies for a period of 22 months, which exhibited the production of forager nymphs all year round. A biometric study was conducted to determine the instars of the forager nymphs collected. The identification of male and female nymphs was also conducted for establishing the sex proportion, which was slightly male-biased. From the 533 forager nymphs collected, 34 were from the 3rd instar, 280 from the 4th instar and 219 from 5th instar. The results suggest that 3rd instar nymphs were not too active in the foraging activities because they were collected only in one colony and in an insignificant quantity. (C) Koninklijke Brill NV, Leiden, 2011.

Innate Immunity in Wooless Lamb to Larvae of Amblyomma cajennense Tick (Fabricius, 1787) (Acari: Ixodidae)

P>The Cayenne tick Amblyomma cajennense infests preferably horses in its adult form but other mammal species in its immature stages and is the main vector of Rickettsia rickettsii, the Brazilian spotted fever pathogen. As wooless lambs are often raised on pasture together with horses, an experiment was performed to investigate their possible acquisition of resistance to A. cajennense after experimental infestations. Seven naive wooless lambs were infested thrice at 60 days interval with immature and adult instars of A. cajennense from a laboratory colony, the tick biotic potential being determined and biopsies of tick bite lesions taken to investigate the inflammatory cell component. Nearly 100% of larvae died in all infestations, while nymphs and adults fed normally throughout re-infestations. Microscopic features of adult tick bite lesions revealed predominance of neutrophils (38%) and eosinophils (36.8%), respectively, in the first and second infestations. In the third infestation, 43.6% of MN cells were found and about 31% of eosinophils. on the other hand, nymph bite lesions revealed in all infestations a predominance of eosinophils, increasing from 36% in the first infestation to 50.5% in the third one. It is concluded that wooless lambs present remarkable innate resistance against larvae of A. cajennense, but marked susceptibility to the other tick instars despite the migration of great number of eosinophils to the tick lesion.

Biological aspects of Orius insidiosus (Say) feeding on eggs of Plutella xylostella (Linnaeus) and Anagasta kuehniella (Zeller).

The objective of this work was to evaluate the biology of Orius insidiosus fed on eggs of Plutella xylostella and Anagasta kuehniella. The eggs used were obtained from the Laboratorio de Biologia e Criacao de Insetos, Departamento de Fitossanidade, FCAV/UNESP. The experiment was carried out with a total of 50 12-to-24-hour-old O. insidiosus nymphs, 1 per Petri dish (50 replications). P. xylostella or A. kuehniella eggs were places into each Petri dish daily, along with a small cotton pad moistened with distilled water. The evaluations were carried out daily. The adults were separated in couples, and placed in Petri dishes. The following biological aspects were evaluated: duration, survival rate and consumption of the nymph instars and of the nymph period; longevity of males and females; consumption per day and adult longevity; eggs per day; female fecundity; egg viability; embryonic period; preoviposition period, oviposition period, post-oviposition period. The fertility life table parameters were also evaluated. The predator O. insidiosus did not present significant differences for its biological characteristics, when feeding on P. xylostella and A. kuehniella eggs, however it showed improved fertility life table parameters when fedo n eggs of P. xylostella, suggesting the possibility of using these eggs in the mass rearing of this insect.

Atividade predatória de Euseius citrifolius Denmark & Muma (Acari: Phytoseiidae) sobre Tenuipalpus heveae (Acari: Tenuipalpidae)

The rubber tree red false spider mite, Tenuipalpus heveae Baker, is an important pest of Hevea brasiliensis (Willd. ex. Adr. de Juss.) Muell. Arg. The phytoseiid mite Euseius citrifolius Dennmark & Muma has frequently been recorded on rubber tree crops. The objective of this work was to determine the predatory activity of E. citrifolius on the different life stages (egg, larva, nymph and adult) of T. heveae. The experiments were carried out in Petri dishes (9-cm diameter) containing a layer of wet cotton inside, onto which a disk of rubber tree leaf (2.5-cm diameter) was laid. The disks were taken from naturally infested leaves. Twenty specimens in the life stage that was to be tested were left on the disk and the others were eliminated; a predator life stage (larva, nymph or female) was obtained from a laboratory stock colony and put into each dish. For each tested life stage of E. citrifolius, 4 treatments (T. heveae life stages) and 20 replications were considered in a randomized block design. The observations were made after 24 hours for larvae and nymphs of the predator, and after 24, 48 and 72 hours for the females. E. citrifolius larvae and nymphs had a higher preference for T. heveae larvae followed by nymphs, eggs and adults. Within 72 hours, each predator female consumed 15.0 larvae, 14.5 nymphs, 7.4 adults or 2.2 eggs of T. heveae. It is concluded that E. citrifolius can feed on red false spider mites, the larva and nymph being the preferred stages.

Estudo biológico e morfométrico dos estádios ninfais de Rhodnius neglectus Lent, 1954 (Hemiptera, Reduviidae)

The following parameters of the biological cycle of the Rhodnius neglectus were determined under a temperature of 28°C and relative humidity of the air varying between 52-94%: a) average period of incubation: 13.67 days; b) rate of the eggs eclosion: 86.18%; c) average period of growth of the 1st, 2nd, 3rd, 4th, 5th instar nymphs: 18.91, 15.19, 21.38, 21.34, 30.43 days, respectively; d) percentage of death in the instar nymphs: 13.82, 18.26, 9.95, 8.78, 15.06% respectively; e) percentage of changes per instar nymphs: 86.18, 81.74, 90.05, 91.22, 84.94% respectively. The morphometric study with the stereoscopic microscope and Leica image analyses system, using the Qwin software, of the five instar nymphs showed that in the five instar nymphs a gradual growth of the head, thorax and abdomen occurs. In all the instars the abdomen is the largest segment. In the four first instars the head is larger than the thorax. In the fifth instar the head and the thorax present equivalent sizes.

Estudo biológico e biométrico dos estádios ninfais de Rhodnius prolixus Stäl, 1859 (Hemiptera, Reduviidae) sob condições laboratoriais

Eggs and nymphs originated from couples of Rhodnius prolixus obtained from nymphs of the 5th instar were used for biological cycle and biometric studies. The following biological cycle parameters were determined under a temperature of 28°C and relative humidity, varying between 52 - 94% : medium period of incubation: 13.01 days; rate of eggs eclosion: 77.6%; medium period of development of the 1st, 2nd, 3rd, 4 th, 5th instar nymphs : 19.33, 19.09, 20.38, 24.37, 38.14 days, respectively; percentual of deaths in the nymph instar: 26.70, 14.00, 18.26, 17.02, 35.47% respectively; percentual of changes per instar nymphs; 73.30, 86.03, 81.73, 82.97, 64.52%, respectively. Biometric measurements performed, showed that in all the instars the abdomen is the largest segment. In the four first instars, the head is larger than the thorax. In the fifth instar, the head and thorax present are about the same size.

Níveis constitutivos de compostos fenólicos podem estar relacionados à resistência da cana-de-açúcar à cigarrinha-das-raízes

The interaction of the leafhopper-of-roots with the sugar cane is still poorly marked and there is little information on resistant varieties. The phenolic compounds are involved in resistance mechanisms of the antibiosis type, but few studies are devoted to the studying role of these compounds in the interaction of plants with sucking insects. The study was conducted to determine how the sugar cane responded to the infestation of Mahanarva fimbriolata in terms of accumulation of phenolic compounds. An experiment was carried out under controlled conditions in a randomized design in a factorial schedule 3 x 2 x 4, with 3 genotypes and sugar cane, 2 levels of nymphs infestation of M. fimbriolata and sampling 4 times, with 4 repetitions. The genotypes SP80-1816 and RB72454 showed higher levels of total phenols when subjected to an infestation of the pest, but the duration of the nymphal stage and mortality of sharpshooters were significantly lower in those varieties, indicating that the increase in the concentration of phenolic compounds may had been caused by death and decay of the roots. It was not observed variation in levels of total phenols in the variety SP83- 5073 subject to an infestation of M. fimbriolata. However, the mortality of the leafhopperof- roots and duration of the stage of nymphs were significantly higher in genotype, indicating the existence of resistance-type antibiosis. Analysis of correlation showed that higher initial levels of phenolic compounds resulting in mortality of the pest can increase the duration of the nymph stage.

Herbivoria em soja: Efeito na composição química das folhas e na biologia da lagarta da soja e do percevejo verde pequeno

The objective of this research was to study the effect of previous herbivory in the chemical composition of soybean leaves, and its influence on Anticarsia gemmatalis (Hüeb.) and Piezodorus guildinii (West.) development. Two soybean genotypes, 'Embrapa 4' and 'BR 37', were chemically analyzed. The caterpillars were fed on these genotypes leaves and the bugs on string beans, both injured and non- injured (control), totalizing 4 treatments with 50 replications for each treatment. Herbivory was performed by releasing 3rd instar velvetbean caterpillar. The caterpillars were taken out when 30%-40% of foliar area were consumed. After that, leaves and string beans were used in the experiment. The results obtained during this research indicate that leaves chemical composition was altered and that, in general, A. gemmatalis larvae and P. guildinii nymph have presented better development when fed on non-injured soybean plants, being 'Embrapa 4' genotype the most efficient one concerning insects development.