Demographic potential of the pupal parasitoid Trichopria drosophilae (Hymenoptera: Diapriidae) reared on Drosophila suzukii (Diptera: Drosophilidae)

Highlights

• A standard life table was constructed for Trichopria drosophilae from East China.

• Drosophila suzukii pupae reared in laboratory can be used by the parasitoid as hosts.

• Parameters regarding reproduction and population increase were obtained.

• The parasitoid showed high demographic potential to control the pest insect.

Abstract

Parasitoids represent a potential tool to control the invasive spotted wing drosophila, Drosophila suzukii, which has invaded Europe and America, recently. A good example is the pupal parasitoid, Trichopria drosophilae, would be an effective biocontrol agent. Populations of D. suzukii, and T. drosophilae were collected from a blueberry orchard in East China and reared in the laboratory at 25 °C. Life table and population growth data for T. drosophilae were obtained using D. suzukii pupae as a host. Mean adult longevity was 22.40 d and 26.45 d, for females and males respectively. The mean oviposition period was 18.20 d. The daily mean parasitization rate was 9.47% per female when 30 hosts were daily provided. The total number of T. drosophilae offspring throughout a lifetime was 63.45 per female, and the female offspring proportion was 65.06%. The intrinsic rate of natural increase and the finite rate of increase were 0.18 and 1.19, respectively. The generation time and the population doubling time were 21.29 d and 3.91 d, respectively. Our results suggest that T. drosophilae population differed among populations in population growth parameters, and those from China also has the parasitism potential to control D. suzukii.

Introduction

The spotted wing drosophila, Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae), is a key pest of soft and thin skinned fruits such as cherries, blueberries, blackberries, raspberries, strawberries, etc. (Asplen et al., 2015, Hamby et al., 2013, Lee et al., 2011). Most drosophila species attack only decaying or rotting fruits, e.g. the common species D. melanogaster. But unlike most other drosophila, D. suzukii females lay eggs in ripening fruits preharvest by cutting the fruit skin with their serrated ovipositor(Hamby et al., 2016). Larvae then feed on the fruit pulp, which makes the fruits useless for market and reduces crop yield (Arno et al., 2016, Lee et al., 2016, Rota-Stabelli et al., 2013). D. suzukii causes great economic damage worldwide. For example, annual loses attributed to this species of drosophila are estimated to be $390 million in California, USA (Walsh et al., 2011) and more than €3.3 million in Trentino, Italy (Ros et al., 2013).

This species of drosophila has a wide host range and a short generation time, making effective management of this pest challenging. Current control efforts depend heavily on insecticides, such as organophosphates, pyrethroids, and spinosyns (Haye et al., 2016, Rogers et al., 2016, Wiman et al., 2016). And in certain cases even methyl bromide (MB) fumigation has been attempted in post-harvest (Walse et al., 2012). Biological control, especially using parasitoids, may be helpful to reduce the insect pest (Wiman et al., 2016). Different parasitoid species, including larval and pupal parasitoids, have been reported in different regions.

There are approximately 50 hymenopterous parasitoid species to Drosophila which belong to four families: the larval parasitoids, Braconidae and Eucoilidae, and the pupal parasitoids, Diapriidae and Pteromalidae (Carton et al., 1986, Fleury et al., 2009). Most larval parasitoids cannot develop in D. suzukii because of its strong immune response in the laboratory (Chabert et al., 2012, Kacsoh and Schlenke, 2012, Rossi Stacconi et al., 2015), and in the field (Wang et al., 2016c). However, the pupal parasitoids Trichopria drosophilae (Hymenoptera: Diapriidae) and Pachycrepoideus vindemmiae (Hymenoptera: Pteromalidae) can successfully develop in D. suzukii (Chabert et al., 2012, Kacsoh and Schlenke, 2012, Wang et al., 2016a, Wang et al., 2016b). T. drosophilae is an endoparasitic, idiobiont parasitoid whose host range is known to be limited within Drosophilae (Carton et al., 1986, Le Lann et al., 2014). As some reports have demonstrated that this parasitoid can parasitize D. suzukii in field samples in the North American, Europe and Asia (Daane et al., 2016, Gabarra et al., 2015, Wang et al., 2016a, Wang et al., 2016b), T. drosophilae could be more efficient in laboratory tests of D. suzukii parasitism when compared to other pupal parasitoids, such as P. vindemiae (Wang et al., 2016a). Understanding the biology of T. drosophilae could lead to an increase in the rearing and releasing of this parasitoid in fields to control D. suzukii (Mazzetto et al., 2016).

The objective of this study was to determine the demographic parameters of T. drosophilae from East China and evaluate the effects of this parasitoid on D. suzukii. Wang et al. (2016b) have reported the longevity, reproduction, and intrinsic rate of populations from Californian and South Korean. Understanding the biological potential of populations of this parasitoid originating from different countries is necessary to select the most suitable populations.