Abstract The life cycle, sex ratio and predatory capacity of the syrphid Ocyptamus gastrostactus (Wiedemann, 1830) fed with the aphid Aphis craccivora Koch, 1854 were studied under laboratory conditions. The predator was collected in El Cují (10° 09´18.59” N 69° 18´20.43” W, 580 m), Iribarren municipality, Lara state, Venezuela, while the prey was obtained from Gliricidia sepium plants (Jacq.) Kunth ex Walpers in the University Park of the Universidad Centroccidental Lisandro Alvarado (UCLA), Venezuela. Both were reared under laboratory conditions at a temperature of 24 ± 1 °C, 56 ± 11% RH, 27 ± 1 °C, 49 ± 4% RH and 12:12 photoperiod (D: N). The average time in days of the life cycle (egg-adult) of O. gastrostactus was 17.65 ± 0.22 (egg 2.00 ± 0.00; larva 8.26 ± 0.23 and pupa 7.39 ± 0.15). This study presents for the first time data on the full duration of the developmental phases of O. gastrostactus under controlled conditions. The sex ratio of the progeny (male: female) was 1: 1.38. The predatory capacity was studied with the densities of 50, 70, 90, 110 and 130 aphids. Average daily larval predation values ranged from 46.60 ± 0.42 to 111,67 ± 0,88 aphids at the densities of 50 and 130 aphids respectively.

Resumen Se estudiaron el ciclo de vida, la proporción sexual y la capacidad depredadora del sírfido Ocyptamus gastrostactus (Wiedemann, 1830) alimentado con el áfido Aphis craccivora Koch, 1854 en condiciones de laboratorio. El depredador fue recolectado en El Cují (10°09´18,59” N 69°18´20,43” O, 580 m), municipio Iribarren, estado Lara, Venezuela, mientras que la presa se obtuvo de plantas de Gliricidia sepium (Jacq.) Kunth ex Walpers en el Parque Universitario de la Universidad Centroccidental Lisandro Alvarado (UCLA), Venezuela. Ambos fueron criados bajo condiciones de laboratorio a una temperatura de 24 ± 1 °C, 56 ± 11% HR, 27 ± 1 °C, 49 ± 4% HR y fotoperiodo 12:12 (D: N). El tiempo promedio en días del ciclo de vida (huevo-adulto) de O. gastrostactus fue de 17,65 ± 0,22 (huevo 2,00 ± 0,00; larva 8,26 ± 0,23 y pupa 7,39 ± 0,15). En este estudio se presentan por primera vez los datos sobre la duración completa de las fases de desarrollo de O. gastrostactus en condiciones controladas. La proporción sexual de la progenie (macho: hembra) fue 1: 1,38. La capacidad depredadora fue estudiada con las densidades de 50, 70, 90, 110 y 130 áfidos. Los valores promedio diarios de depredación de la larva variaron desde 46,60 ± 0,42 hasta 111,67 ± 0,88 áfidos a las densidades de 50 y 130 áfidos respectivamente.

Este estudo descreve a fauna de insetos predadores, parasitóides e formigas associada a pulgões em couve (Brassica oleracea L. var. acephala D.C.), cultivada em sistema orgânico. O pulgão foi identificado como Lipaphis pseudobrassicae Davis, sendo este o primeiro registro da espécie atacando couve no Brasil. Parasitismo primário por Diaeretiella sp. e Aphidius sp. e hiperparasitismo por Aphydencyrtus sp., Alloxysta sp., Pachyneuron sp. e Syrphophagus sp. foram observados. Vinte espécies de Coccinellidae foram coletadas, sendo que oito delas foram observadas, tanto na fase adulta como larval, atacando o pulgão: Hyperaspis (Hyperaspis) festiva Mulsant, que foi a mais abundante (72,5% do total de insetos predadores obtidos), Cycloneda sanguinea (L.), Eriopis connexa Germar, Coleomegilla maculata DeGeer, Hippodamia convergens Guérin, Heterodiomus sp., Scymnus (Pullus) sp.1 e Scymnus (Pullus) sp.2. Larvas de Syrphidae afidófagas coletadas nas folhas de couve infestadas por L. pseudobrassicae pertencem às espécies Allograpta exotica (Wiedemann) e Ocyptamus gastrostactus (Wiedemann). Larvas e pupas de Syrphidae foram parasitadas por Pachyneuron sp., Syrphophagus sp. e Diplazon laetatorius Fabricius. Larvas de Chrysopodes sp. foram observadas alimentando-se de L. pseudobrassicae. Espécies de formigas associadas às colônias desse pulgão foram Ectatomma quadridens Fabricius e Pheidole sp.

This study describes the fauna of predator insects, parasitoids and ants associated with aphids on kale (Brassica oleracea L. var. acephala D.C.) in organic system. The aphid was identified as Lipaphis pseudobrassicae Davis, and this is the first record of the species attacking kale in Brazil. Primary parasitism by Diaeretiella sp. and Aphidius sp. and hyperparasitism by Aphydencyrtus sp., Alloxysta sp., Pachyneuron sp. and Syrphophagus sp. were observed. Twenty species of Coccinellidae were collected, and eight of them were observed in adult and larval stages attacking the aphid: Hyperaspis (Hyperaspis) festiva Mulsant, which was the most abundant (72.5% of all predator insects obtained), Cycloneda sanguinea (L.), Eriopis connexa Germar, Coleomegilla maculata DeGeer, Hippodamia convergens Guérin, Heterodiomus sp., Scymnus (Pullus) sp.1 and Scymnus (Pullus) sp.2. Aphidophagous Syrphidae larvae collected on leaves of kale infested by L. pseudobrassicae belong to the species Allograpta exotica (Wiedemann) and Ocyptamus gastrostactus (Wiedemann). Larvae and pupae of Syrphidae were parasitized by Pachyneuron sp., Syrphophagus sp. and Diplazon laetatorius Fabricius. Larvae of Chrysopodes sp. were observed feeding on L. pseudobrassicae. Species of ants associated with the colony of this aphid were Ectatomma quadridens Fabricius and Pheidole sp.

A ocorrência de sirfídeos afidófagos nas culturas de citros, couve, pepino, trigo e batata foi registrada. As amostragens foram realizadas, quinzenalmente, de agosto a dezembro de 2002. Constatou-se as espécies:Ocyptamus gastrostactus (Wiedemann, 1830), Allograpta exotica (Wiedemann, 1830), Pseudodorus clavatus (Fabricius, 1794) e Ocyptamus anthiphates (Walker, 1849). P. clavatus ocorreu em todas as culturas amostradas, com a maior densidade populacional (72%), seguido de O. gastrostactus (16%), A. exotica (11%) e O. anthiphates (1%). A ocorrência dos sirfídeos esteve correlacionada com os fatores climáticos e a presença dos afídeos.

The occurrence of aphidophagous syrphids was studied on citrus, cabbage, cucumber, wheat and potato crops. Samplings were done every 15 days from August to December 2002. The species recorded were: Ocyptamus gastrostactus (Wiedemann, 1830), Allograpta exotica (Wiedemann, 1830), Pseudodorus clavatus (Fabricius, 1794) and Ocyptamus anthiphates (Walker, 1849). P. clavatus occurred on all the crops and showed the highest population density (72%). It was followed by O. gastrostactus (16%), A. exotica (11%) and O. anthiphates (1%). The occurrence of the syrphids was correlated with the weather conditions and the presence of aphids.