Parasitism and predation of the planthopper Tagosodes orizicolus (Homoptera: Delphacidae) by a dryinid parasitoid in Costa Rica / Parasitismo y depredación del saltamontes Tagosodes orizicolus (Homoptera: Delphacidae) por un parasitoide dryinido en Costa Rica

We analyzed the effect of predation and parasitism by the native dryinid Haplogonatopus hernandezae as a natural enemy of the rice pest Tagosodes orizicolus under controlled conditions in an insectary in Costa Rica. We found no change in the proportion of T. orizicolus nymphs that were fed upon, parasitized, and that showed no apparent damage throughout the adult stage in H. hernandezae, which favors a stable control of the pest. The percentage of T. orizicolus nymphs that were parasitized (37 %) and preyed upon (36.5 %) was similar, eliminating 73,5 % of the total nymphs causing damage to the rice plants (N = 1 099). Of the total 324 parasitized nymphs, female nymphs were more parasitized than male nymphs (95 % and 5 % respectively) and dryinids developed more successfully in female host nymphs. These tendencies did not change with dryinid age. Survival of dryinids was higher in female T. orizicolus, both for larvae that emerged from the host and pupated, and for pupae that moulted to adults. In cages where the nymphs had no contact with dryinids we found a higher amount of males than females (57.44 ± 28.5 vs 45.22 ± 25.85). In contrast, when the nymphs were in contact with dryinids, the sex ratio was two females to one male reaching adulthood since the dryinids fed more on male nymphs (N = 692). Our results indicate that female dryinids prefer to oviposit in female T. orizicolus nymphs and prey on males. Reproduction by parthenogenesis, acceleration of the development in an insectary with controlled conditions and eficiency of H. hernandezae as a parasitoid and predator indicate that this dryinid is an effective biological control agent of T. orizicolus. Rev. Biol. Trop. 57 (Suppl. 1): 203-211. Epub 2009 November 30.

En un insectario en condiciones controladas analizamos los efectos de depredación y parasitismo del dryinido Haplogonatopus hernandezae, enemigo natural del vector del virus de la hoja blanca Tagosodes orizicolus. Nuestros resultados indican que la proporción de depredación y parasitismo es estable a lo largo de la vida del dryinido lo cual favorece un control continuo eliminando 73% de la plaga (N = 1 099). De un total de 324 ninfas de T. orizicolus parasitadas, las hembras fueron más parasitadas que los machos y las larvas del dryinido se lograron desarrollar exitosamente a partir de ninfas hembra en contraste con las ninfas macho. Encontramos una mayor proporción de machos en comparación con las hembras en las jaulas de T. orizicolus en que las ninfas no tuvieron ningún contacto con hembras del dryinido (57.44 ± 28.5 vs. 45.22 ± 25.85). Al contrario, cuando las ninfas estuvieron en contacto con las hembras del dryinido, la proporción de sexos fue de dos hembras por cada macho. Este resultado indica que las hembras del dryinido prefieren ovipositar en las hembras de T. orizicolus y alimentarse de las ninfas macho. La reproducción por partenogénesis, aceleración de las etapas de desarrollo en condiciones controladas, y la eficiencia como parasitoide y depredador de este dryinido indican su efectividad como agente de control biológico de T. orizicolus.

A reliable bioassay procedure to evaluate per os toxicity of Bacillus thuringiensis strains against the rice delphacid, Tagosodes orizicolus (Homoptera: Delphacidae)

A reliable bioassay procedure was developed to test ingested Bacillus thuringiensis (Bt) toxins on the rice delphacid Tagosodes orizicolus. Initially, several colonies were established under greenhouse conditions, using rice plants to nurture the insect. For the bioassay, an in vitro feeding system was developed for third to fourth instar nymphs. Insects were fed through Parafilm membranes on sugar (10 % sucrose) and honey bee (1:48 vol/vol) solutions, observing a natural mortality of 10-15 % and 0-5 %, respectively. Results were reproducible under controlled conditions during the assay (18±0.1 °C at night and 28±0.1 °C during the day, 80 % RH and a 12:12 day:light photoperiod). In addition, natural mortality was quantified on insect colonies, collected from three different geographic areas of Costa Rica, with no significant differences between colonies under controlled conditions. Finally, bioassays were performed to evaluate the toxicity of a Bt collection on T. orizicolus. A preliminary sample of twenty-seven Bt strains was evaluated on coarse bioassays using three loops of sporulated colonies in 9 ml of liquid diet, the strains that exhibited higher percentages of T. orizicolus mortality were further analyzed in bioassays using lyophilized spores and crystals (1 mg/ml). As a result, strains 26-O-to, 40-X-m, 43S-d and 23-O-to isolated from homopteran insects showed mortalities of 74, 96, 44 and 82 % respectively while HD-137, HD-1 and Bti showed 19, 83 and 95 % mortalities. Controls showed mortalities between 0 and 10 % in all bioassays. This is the first report of a reliable bioassay procedure to evaluate per os toxicity for a homopteran species using Bacillus thuringiensis strains. Rev. Biol. Trop. 55 (2): 373-383. Epub 2007 June, 29.

Se desarrolló una metodología de bioensayo para evaluar toxinas de Bacillus thuringiensis (Bt) ingeridas por Tagosodes orizicolus, plaga del arroz y vector del virus de la hoja blanca. Se establecieron colonias del insecto en condiciones de invernadero usando plantas de arroz como alimento. Para el bioensayo, se desarrolló un sistema de alimentación in vitro para ninfas de tercer y cuarto estadío. Los insectos se alimentaron de soluciones de miel de abeja (1:48 vol/vol) y sacarosa (10 %) a través de membranas de Parafilm. Se observaron mortalidades del 10-15 % y 0-5 %, respectivamente, en ambas dietas. Los resultados fueron reproducibles en condiciones controladas de humedad y temperatura (18±0.1 °C de noche y 28±0.1 °C de día, 80 % H.R y a 12:12 fotoperíodo día:noche). Asimismo, se analizó la mortalidad natural de los insectos según su procedencia, sin embargo, no se observaron diferencias significativas en condiciones controladas. Finalmente, se elaboraron bioensayos para evaluar la toxicidad de una colección de cepas de Bt contra T. orizicolus. Se evaluó preliminarmente, una submuestra de 27 cepas de Bt en bioensayos burdos usando tres asadas como inóculo para 9 ml de dieta líquida. Posteriormente, las cepas que mostraron los mayores porcentajes de mortalidad se evaluaron en bioensayos usando esporas y cristales liofilizados (1 mg/ml). Como resultado, las cepas aisladas a partir de homópteros 26-O-to, 40-X-m, 43-S-d y 23-O-to mostraron mortalidades de 74, 96, 44 y 82 % respectivamente, mientras que las HD-137, HD-1 y Bti mostraron 19, 83 y 95 % de mortalidad. Los controles presentaron mortalidades de 0 y 10 % en los bioensayos. Este es el primer informe de un bioensayo para evaluar la toxicidad de cepas de Bt utilizando la especie T. orizicolus.

Duas novas espécies de Enchenopa Amyot & Serville (Hemiptera, Membracidae) do semi-árido do Estado da Paraíba, Brasil / Two new species of Enchenopa Amyot & Serville (Hemiptera, Membracidae) from the semi-arid region of Paraiba State, Brazil

Enchenopa euniceae sp. nov. and E. minuta sp. nov. (both from São José dos Cordeiros, Paraíba, Brasil) are described and illustrated.

Enchenopa eunicea sp. nov. e Enchenopa minuta sp. nov. (ambas de São José dos Cordeiros, Paraíba, Brasil ) são descritas e ilustradas.

New species of the treehopper tribe Amastrini (Hemiptera, Membracidae, Smiliinae)

Three new species of Amastris Stål and one of Erosne Stål are described and illustrated. Amastris rotheai sp. nov. (Paraiba, Brazil), A. gibberula sp. nov. (Mato Grosso, Brazil), A. comarapa sp. nov. (Santa Cruz, Bolivia), and Erosne parvula sp. nov. (Paraiba, Brazil).

Três novas espécies de Amastris Stål e uma de Erosne Stål são descritas e ilustradas. Amastris rotheai sp. nov. (Paraíba, Brasil), A. gibberula sp. nov. (Mato Grosso, Brasil), A. comarapa sp. nov. (Santa Cruz, Bolívia) e Erosne parvula sp. nov. (Paraíba, Brasil).

Descrição da fêmea de Paracentronodus nevesi Barreira & Sakakibara (Hemiptera, Membracidae) / Description of the female of Paracentronodos nevesi Barreira & Sakakibara (Hemiptera, Membracidae)

A female specimen of Paracentronodos nevesi Barreira & Sakakibara, 2001 was collected in a semi-arid region (Caatinga) of the State of Paraíba, Brazil, at the municipality of São José dos Cordeiros. Since only the male was known, the specimen is described and illustrated.

Um exemplar fêmea de Paracentronodus nevesi Barreira & Sakakibara, 2001, de São José dos Cordeiros, região de semi-árido (Caatinga), do Estado da Paraíba, é descrito e ilustrado. Até o presente, apenas o macho era conhecido.

Nova espécie de Parabahita Linnavuori (Homoptera: Cicadellidae: Deltocephalinae)

A new species of Parabahita Linnavuori, 1959 is described and illustrated: Parabahita caudata sp. nov. (Brazil, Rondônia)

Uma nova espécie de Parabahita Linnavuori, 1959 é descrita e ilustrada: Parabahita caudata sp. nov. (Brasil, Rondônia)