Niche differentiation of two pupal parasitoid wasps of Musca domestica (Diptera: Muscidae): Pachycrepoideus vindemmiae and Spalangia endius (Hymenoptera: Pteromalidae)

In nature, competing species often achieve coexistence through niche differentiation. We examined this phenomenon for Pachycrepoideus vindemmiae and Spalangia endius (Hymenoptera: Pteromalidae), two species of pupal parasitoids that are considered biological control agents of house fly, Musca domestica (Diptera: Muscidae). We examined the ability of each species, alone and in combination, to locate host pupae buried at different depths (0, 1, 2, 4, and 6 cm) in three types of substrate (sand, dry wheat bran, and spent fly diet). We then evaluated the competitiveness of each species by allowing first one species, then the other species, to parasitise host individuals within time periods ranging from less than 2 hours to 96 hours of each other. Spalangia endius exhibited greater ability than did P. vindemmiae to locate host pupae buried at depths below one centimetre. Conversely, P. vindemmiae exhibited a greater competitive ability, being more likely to emerge from pupae co-parasitised by S. endius, regardless of oviposition interval or sequence. Our findings suggest that these two parasitoid species coexist through niche differentiation. Our findings also indicate that to increase the effectiveness of biological control, the environmental conditions and risk of interspecific competition should be considered when selecting parasitoid species for release.

Annotated checklist and illustrated key to parasitoids (Hymenoptera: Diapriidae, Eulophidae and Pteromalidae) of fruit flies (Diptera, Tephritidae) in Brazil

The hymenopteran parasitoids of pest species of Tephritidae in Brazil are best known by their most prominent species, members of Braconidae and Figitidae. Species in the less-studied families Diapriidae, Eulophidae and Pteromalidae, which are mostly pupal parasitoids, have been largely neglected and the literature on these groups is sparse and scattered. Therefore, their importance as natural enemies of fruit flies is likely underestimated. Here, we present a parasitoid-host-plant checklist of all diapriids, eulophids and pteromalids that parasitize fruit flies of economic importance in Brazil, namely Anastrepha species and Ceratitis capitata. A compilation of information of the seven species of these parasitoids occurring in Brazil—Coptera haywardi Loiácono and Trichopria anastrephae Lima (Diapriidae), Tetrastichus giffardianus Silvestri (Eulophidae), Pachycrepoideus vindemmiae (Rondani), Spalangia endius Walker, S. gemina Bouček and S. simplex Perkins (Pteromalidae)—including their taxonomic status, general biology, and potential as biocontrol agents, is presented. Additionally, we provide an illustrated key to species, aiming to highlight key morphological features and facilitate identification at species level, stimulating future research on these groups.

Associations between the larval-pupal parasitoids Erycia furibunda and E. festinans (Diptera: Tachinidae) and respectively, the sympatric and syntopic butterflies Euphydryas aurinia provincialis and Melitaea cinxia (Lepidoptera: Nymphalidae)

Several studies on butterfly ecology and biology of Melitaeini butterflies have been carried out in the past, however the factors affecting butterfly mortality and the role of natural enemies on population dynamics are not yet fully known. Larval survival plays a key role in determining butterfly population size and distribution range; thus, knowing the sources and variation in larval mortality is essential understanding and predicting population dynamics. Butterfly larval mortality is generally ascribed to abiotic factors, predators and parasitoids (mainly Diptera and Hymenoptera). Among Diptera, tachinids parasitize primarily larval Lepidoptera. In this paper, we report the results of 5-year observations in the wild and captivity on the tachinids, Erycia furibunda and E. festinans, parasitoids of caterpillars of a population of Euphydryas aurinia spp. provincialis and Melitaea cinxia in Central Italy revealing their host specifity. The hosts, E. aurinia and M. cinxia, and parasitoids, E. furibunda and E. festinans, inhabit the same habitat and their life cycles highly overlap, nevertheless, the parasitoids maintain their host specifity: E. furibunda as parasitoid of E. aurinia; E. festinans as parasitoid of M. cinxia. This was confirmed by our findings during the butterfly breeding activities carried out for over five years. Although the role of chemical cues in host finding requires further research, according to our observations the presence of only E. furibunda on larval webs of E. aurinia let us suppose that the mechanism by which E. furibunda locates its host could be based on olfactory cues emitted by feeding damage to host plants that act from afar. Similarly, the mechanism of host finding used by E. festinans could act to select its host, M. cinxia. Furthermore, we illustrate some diagnostic features of adults for the identification of the studied parasitoids.

Multiscale Determinants Drive Parasitization of Drosophilidae by Hymenopteran Parasitoids in Agricultural Landscapes

(1) The management of agricultural landscapes for pest suppression requires a thorough understanding of multiple determinants controlling their presence. We investigated the ecological preferences of indigenous parasitoids and their drosophilid hosts to understand the role of native parasitoids as biological control agents of the invasive frugivorous Drosophila suzukii. (2) Using data from an extensive field survey across different habitat types we analyzed the influence of abiotic and biotic factors on parasitoid and drosophilid communities at multiscale levels. (3) Eight parasitoid and 27 drosophilid species were identified. Thirty-four percent variation in drosophilid communities was explained by factors at the landscape scale, and 52% of significant variation of parasitoids by local distribution of three drosophilid species, mainly collected in woodland. Parasitoid communities were significantly influenced by microhabitat type (ground versus canopy) rather than habitat type. All parasitoids except Pachycrepoideus vindemmiae preferred the ground microhabitat. All parasitoids, with the exception of Trichopria drosophilae and Spalangia erythromera, displayed significant preferences among the drosophilid species used in the baited traps. (4) Since they can tolerate a broad range of habitat factors, altogether pupal parasitoids investigated in this study could play a role in biological control programs to suppress D. suzukii, but non-target effects have to be regarded.

Life History and Host Preference of Trichopria drosophilae from Southern China, One of the Effective Pupal Parasitoids on the Drosophila Species

This study aims to evaluate several life-history traits of a T. drosophilae population from southern China and its parasitic preference of three Drosophila species. For mated T. drosophilae females, the mean oviposition and parasitization period were 27.20 and 37.80 d, respectively. The daily mean parasitization rate was 59.24% per female and the lifetime number of emerged progeny was 134.30 per female. Trichopria drosophilae females survived 37.90 and 71.61 d under host-provided and host-deprived conditions, respectively. To assess the potential for unmated reproduction in T. drosophilae, the mean oviposition and parasitization period of unmated females was 22.90 and 47.70 d, respectively. They had a daily mean parasitization rate of 64.68%, produced a total of 114.80 offspring over their lifetime, and survived 52 d. Moreover, T. drosophilae showed a preference towards D. suzukii based on the total number of emerged offspring under a choice test. Our findings indicate that T. drosophilae from southern China appears to be suitable for the control of D. suzukii in invaded areas, due to its reproductive potential.