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- Abundance of Epiphyas postvittana (Walker, 1863) in forestry nurseries of São Miguel Island (Azores, Portugal) (Lepidoptera: Tortricidae)Publication . Oliveira, Luísa; Vieira, Virgilio; Soares, António O.; Borges, Isabel; Arruda, Patrícia Melo; Tavares, JoãoEpiphyas postvittana (Walker, 1863) is an invasive polyphagous pest for the Azores and its bioecology and the potential natural enemies were unknown. We evaluated the temporal profile of this species larval abundance and the number of males captured in sex pheromone traps, hypothesizing that both profiles were similar. The study was carried out on seven endemic host plants and one native species grown in two forest nurseries (Furnas and Nordeste) in São Miguel Island over two years from 2018 to 2019. A total of 827 plants attacked by E. postvittana were observed in Furnas nursery (2018: 503, 2019: 324) and 1227 in the Nordeste (2018: 649, 2019: 578), including the presence of 525 larvae distributed by the Furnas (2018: 178, 2019: 79) and from the Nordeste (2018: 131, 2019: 137). In 2019, the average weekly number of males captured in the sex pheromone traps (total 31 weeks) were higher in Furnas (mean ± SE: 9.68 ± 1.982) than in Nordeste (3.33 ± 0.651). In synthesis, (i) the population density varied throughout the year and as a function of the host plant species in production; (ii) the abundance profile of larval and adults suggests has at least three to four generations per year and that adults are active year-round, experiencing some delayed development during the winter; (iii) a low larval density does not represent very serious damage to Azorean endemic plants, but is reflected in the population density of its natural enemies; (iv) some biological control agents are present in the field, parasitizing the larvae (i.e., Braconidae species of Meteorus ictericus (Nees, 1811) and Microgaster opheltes Nixon, 1968); (v) finally, the knowledge of the population dynamics and its natural enemies needs further and long-term study.
- Can the ladybird predator Scymnus nubilus contribute to control of the aphid Aphis frangulae, a pest threatening the Macaronesia endemic Frangula azorica?Publication . Borges, Isabel; Arruda, Patrícia Melo; Meseguer, Roberto; Vieira, Virgilio; Pons-Solé, Gemma; Soares, António O.Aphis frangulae (Hemiptera: Aphididae) is a major pest of the laurel forest endemic Frangula azorica (Rosales: Rhamnaceae) produced in nursery conditions by the Forestry Services of the Azores (Portugal). The suitability of A. frangulae for the development and reproduction of a potential biological control agent, Scymnus nubilus (Coleoptera: Coccinellidae), was assessed under laboratory conditions (25 ± 1 °C, 75 ± 5% RH, 16:8 L:D photoperiod). The predation potential of S. nubilus was also assessed. Scymnus nubilus 4th instar larvae and pupae successfully completed development in 9.0 ± 0.2 days. The 4th instar larvae ate 15.1 aphids per day, corresponding to 1.52 mg of biomass ingested. On A. frangulae, S. nubilus females took 5.5 ± 0.3 days to start oviposition and an average of 135 ± 12 eggs were laid per female over the first 15 days of oviposition. Field tests showed that S. nubilus 4th instar larvae were more efficient in controlling the pest in closed systems (isolated aphid colonies) and the effect was more pronounced at high predator densities within three days. In open systems, the aphid natural control was higher than initially expected. This work highlights the role of the large aphidophagous guild present in forestry nurseries. The results of this study show that A. frangulae is an essential prey species for S. nubilus and therefore the predator can be used in pest management programs against this pest. However, further studies focusing on different biological control tactics (inundative or inoculative) are required to assess more accurately the effectiveness of S. nubilus as a biological control agent against A. frangulae.