Parasitoids of Dasiops (Diptera: Lonchaeidae) in sweet granadilla orchards in an Andean forest of Peru

ABSTRACT We report hymenopteran larval and pupal parasitoids of the Dasiops species in sweet granadilla (Passiflora ligularis J.) orchards in a Peruvian Andean forest. Flower bud and fruit samples infested by Dasiops were collected in three orchards from Oxapampa (Pasco, Peru). In addition, we exposed non-parasitized Dasiops pupae at ground level to verify the presence of pupal parasitoids. We identified Utetes anastrephae (Viereck) and Opius sp. (Hymenoptera: Braconidae) on flower buds infested b.y Dasiops inedulis Steyskal. However, Aganaspis pelleranoi (Brèthes) (Hymenoptera: Figitidae) emerged from D. frieseni pupae reared from unripe fruits. Also, the pupal parasitoids Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) and Coptera sp. (Hymenoptera: Diapriidae) emerged from pupae of both D. inedulis and D. frieseni exposed to parasitism at ground level. Our findings shed new light into new interactions for species in the genus Dasiops and their larval and pupal parasitoids in sweet granadilla agroecosystems from the Neotropical region.


RESUMEN
El objetivo de esta investigación fue registrar las especies de hymenópteros parasitoides de larva y pupa de Dasiops en fincas de granadilla (Passiflora ligularis J.) localizadas en una selva andina de Perú. Muestras de botones florales y frutos infestados por Dasiops fueron colectados en tres fincas en la provincia de Oxapampa (Pasco, Perú). Asimismo, pupas de Dasiops no parasitadas fueron expuestas al suelo para la verificación de parasitoides de pupa. In agroecosystems, cultivated plants are constantly damaged by key insect pests who promote significant losses in production for the farmers [1]. Among these insects, the lance flies (Diptera: Tephritoidea: Lonchaeidae) are important pests of several commercial and non-commercial passion flowers (Passifloraceae) in the Neotropical region. In Peru, two Dasiops species have recently been reported to cause damage on sweet granadilla. Dasiops inedulis Steyskal that feeds on ovaries and anthers of flower buds causing it to rot and drop to the ground, and Dasiops frieseni Norrbom & McAlpine that feeds on the pulp and seeds of young unripe fruits causing them to wrinkle [2,3]. These insects cause high losses in fruit production and infestation levels can reach up to 80% in commercial passion flowers [4,5].
Native parasitoids play an important function in the natural suppression of various pest species of Tephritoidea in agroecosystems in the Neotropical region [6]. In this regard, biological control may help suppress Dasiops population densities and provide a new tool to reduce environmental risks and improve public health. However, to date, there is limited information available on the tritrophic interactions among passion flowers, Dasiops, and their parasitoids. Thus, we aimed to identify the diversity of larval and pupal parasitoids associated with Dasiops species in sweet granadilla orchards in an Andean forest of Peru.
Field trials were done from January to August 2013 in three conventional sweet granadilla orchards (2-4 years old; 1.5-2 ha). Each orchard (named "Cantarizú," "Grapanazú," and "San Marcos") was located in three different districts in Oxapampa (Pasco, Peru) ( Figure 1). Oxapampa is a province located on the eastern slope of the Andean mountains (central tropical forest) and recognized as the principal production area of sweet granadilla in Peru, with half of the total national Peruvian production [7]. All sweet granadilla orchards used in this study were surrounded by native forest associated with some cultivated plants such as lemon (Citrus limonia Osbeck) and guava (Psidium guajava L.) in Cantarizú; coffee (Coffea arabica L.), chili pepper (Capsicum annuum L.), and guava in Grapanazú; and loquat (Eriobotrya japonica L.), stuffing cucumber (Cyclanthera pedata Schrad.), and lucumo (Pouteria lucuma [Ruiz and Pav.]) in San Marcos.
We collected twelve flower buds (Figure 2(a)) and fruit (Figure 2(b)) samples (a sample = eight flower buds or four fruits) in six different weeks from each sweet granadilla orchard. Flower buds and fruits showing symptom of Dasiops damage were sampled to increase the probability of finding larvae. After field collection, samples were taken to the laboratory at Servicio Nacional de Sanidad Agraria (SENASA, Oxapampa) for further processing. In the laboratory, individual samples were weighed and placed in plastic cups (15 cm high x 8 cm diameter) for flower buds or in Styrofoam boxes (38 x 20 × 20 cm) for fruits. In each container, a layer (3 cm) of sterilized and moistened sand was placed in the bottom to allow larval development and pupal formation. Three weeks after field collection, containers were checked, and flower buds and fruits were dissected, for presence of fruit fly larvae or pupae. Pupae were subsequently transferred to plastic cups (250 ml) with sterilized and moistened sand and covered with a fine mesh on the top. Daily, for up to 45 days, plastic cups were checked for adult Dasiops emergence or emergence of larval parasitoids.
To detect pupal parasitoid species in the field, we exposed D. inedulis and D. frieseni pupae to parasitism using the sentinel pupal technique [8]. Pupae were obtained from fruits and flower buds that were infested in the laboratory (and were thus unparasitized). Transparent plastic containers (11 cm diameter × 7 cm height, 250 ml) with the upper part open were buried in the ground under the canopy of sweet granadilla plants and filled with organic substrate. Thereafter, 20 pupae (12-48 hours-old) of the two Dasiops species were exposed separately in different containers. In order to avoid damage by predators and abiotic factors while still allowing access to parasitoids, the containers with pupae were placed inside a nylon mesh (1.5 mm diameter holes) and remained covered under a thin layer of organic substrate (Figure 2(c,d)). Holes were made to the bottom of the containers to avoid water saturation. Monthly, from March to August 2013, pupae of both species were placed in each orchard for 72 hours. After field exposure, pupae were placed inside Petri dishes (10 cm diameter x 1.5 cm height), and taken to the laboratory. Daily, for up to 35 days, Petri dishes were checked for adult Dasiops emergence or emergence of pupal parasitoids. Laboratory conditions were kept at 25 ± 3°C, 65 ± 10% RH, and 12:12 L:D.
Dasiops species identification were confirmed by Pedro Carlos Strikis (Universidade de São Paulo). Larval and pupal parasitoid species were identified based on taxonomical keys. Some parasitoid specimens were confirmed by Angelica Penteado Dias (Universidade Federal de São Carlos, Brazil) and Valmir Costa (Instituto Agronômico de Campinas, Brazil). Voucher specimens of Dasiops and their parasitoids were deposited at the Entomology Museum of the Universidad Nacional Daniel Alcides Carrión (Oxapampa, Pasco, Peru). The parasitism levels found in larvae and pupae of Dasiops were calculated according to the formula: percent parasitism = a/(a + b) × 100, where a = number of emerged adult parasitoids, and b = number of emerged adult Dasiops from each sample.
Two parasitoid species were obtained from exposed D. inedulis and D. frieseni pupae in the field. The wasps Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) and Coptera sp. (Hymenoptera: Diapriidae) ( Table 2). For D. inedulis pupae, P. vindemmiae was the most abundant (71.4%), followed by Coptera sp. (28.6%); resulting in an overall mean parasitism of 5.3%. In contrast, for D. frieseni pupae, Coptera sp. (87.5%) was more abundant than P. vindemmiae (12.5%); resulting in an overall mean parasitism of 3.8% (Table 2). Larval parasitoids are the most commonly reported natural enemies attacking insects of the superfamily Tephritoidea in the Neotropical region, particularly on fruit flies (Diptera: Tephritidae) [6]. However, some surveys done on lance flies in Colombia [5,[9][10][11], Peru [12] and Brazil [13] have recorded parasitoids attacking Dasiops   [5,[9][10][11] (Table 3). No other pupal parasitoid survey has been done on Dasiops in South America. In our study, we found for the first time Coptera sp. emerging from both D. inedulis and D. frieseni pupae in sweet granadilla. There have been no reports of Coptera sp. parasitizing Dasiops pupae in other passion flower crops. Endoparasitoids in the genus Coptera have been widely associated with many fly families, such as Muscidae, Drosophilidae, Lonchaeidae and Tephritidae [16]. For example, Coptera haywardi Loiácono has been considered as a promising candidate for fruit fly biological control [17]. Likewise, our study found that P. vindemmiae attacks pupae of the two Dasiops species in sweet granadilla. This generalist pupal ectoparasitoid usually attacks many cyclorrhapous flies including various fruit fly species [18]. In recent years, P. vindemmiae has received increasing attention as a potential candidate for biological control of the invasive pest Drosophila suzukii (Matsumura) [19].
In summary, this study reports three larval parasitoids and two pupal parasitoids of Dasiops species in sweet granadilla orchards in an Andean forest of Peru. Utetes anastrephae, Opius sp., and Coptera sp. are reported for the first time parasitizing Dasiops in sweet granadilla. This information will assist future research on the development of biological control programs for Dasiops pests in this cropping system and region. Future research on these parasitoids should aim at their conservation and augmentation in biological control programs for suppressing Dasiops populations in sweet granadilla and other passion flower crops.