Assessing the ecological niche and invasion potential of the Asian giant hornet.

The Asian giant hornet (Vespa mandarinia) was recently detected in western British Columbia, Canada and Washington State, United States. V. mandarinia are an invasion concern due to their ability to kill honey bees and affect humans. Here, we used habitat suitability models and dispersal simulations to assess potential invasive spread of V. mandarinia We show V. mandarinia are most likely to establish in areas with warm to cool annual mean temperature, high precipitation, and high human activity. The realized niche of introduced populations is small compared to native populations, suggesting introduced populations could spread into habitats across a broader range of environmental conditions. Dispersal simulations also show that V. mandarinia could rapidly spread throughout western North America without containment. Given its potential negative impacts and capacity for spread, extensive monitoring and eradication efforts throughout western North America are warranted.

Effect of temperature on the post-diapause developmental rate, survival, and body mass of the solitary wasp Isodontia elegans: Implications for rearing of trap-nesting Hymenoptera.

We examined the relationship of post-diapause rearing temperature to developmental rate, survival, and adult body mass of the solitary wasp Isodontia elegans using prepupae from trap-nests. Isodontia elegans is a member of a genus often found in trap-nests in North America and Europe. Trap-nests are commonly used tools for studying cavity-nesting solitary wasps and bees. In temperate zones, progeny in nests usually overwinter as prepupae before pupating and emerging as adults. An important aspect of properly using trap-nests is determining temperatures that affect survival and health of developing offspring. After overwintering >600 cocoons containing prepupae after the summers of 2015 and 2016, we placed cocoons on a laboratory thermal gradient where offspring experienced one of 19 constant temperatures from 6 to 43 °C; emergence of adults was monitored for 100 days. Our conservative estimate for the critical thermal minimum for development is 14 °C, whereas that for the critical maximum is ∼33 °C. Prepupae transitioned to adults most rapidly at 29-33 °C, but developmental rate was lower for some progeny exposed to temperatures ≥30 °C. Offspring successfully reached the adult stage in <100 days at of temperatures of ∼19-33 °C. Adults from cocoons reared at lower temperatures weighed on average 6-10% more than expected based on their head widths, whereas those reared at higher temperatures weighed 4-10% less than expected. The difference may be due to greater rates of water loss and lipid metabolism during development at higher temperatures. Pre-overwintering cocoon mass was a significant predictor of relative adult body mass, indicating that adult health is partly related to their condition before overwintering. The trends we observed were similar to those for the bee Megachile rotundata, which we previously studied on the same gradient apparatus. However, data is needed on many other species of wasps and bees from a diversity of environments.

Effect of Drosophila suzukii on Blueberry VOCs: Chemical Cues for a Pupal Parasitoid, Trichopria anastrephae.

Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical landscape may be altered by the invasion of exotic insect species. The spotted-wing drosophila (SWD), Drosophila suzukii (Diptera: Drosophilidae), is a highly polyphagous fruit pest native to eastern Asia and recently arrived in South America. Our study aimed to characterize the effect of SWD attack on the volatile organic compounds (VOCs) of blueberries, a common host fruit, and to correlate these odor changes with the olfactory-mediated behavioral response of resident populations of Trichopria anastrephae parasitoids, here reported for the first time in Uruguay. Using fruit VOC chemical characterization followed by multivariate analyses of the odor blends of blueberries attacked by SWD, we showed that the development of SWD immature stages inside the fruit generates a different odor profile to that from control fruits (physically damaged and free of damage). These differences can be explained by the diversity, frequency, and amounts of fruit VOCs. The behavioral response of T. anastrephae in Y-tube bioassays showed that female wasps were significantly attracted to volatiles from SWD-attacked blueberries when tested against both clean air and undamaged blueberries. Therefore, T. anastrephae females can use chemical cues from SWD-infested fruits, which may lead to a successful location of their insect host. Since resident parasitoids are able to locate this novel potential host, biological control programs using local populations may be plausible as a strategy for control of SWD.

Fertility life table and biology of Tetrastichus giffardianus (Hymenoptera: Eulophidae) in the larvae of Ceratitis capitata (Diptera: Tephritidae).

Tetrastichus giffardianus is a gregarious koinobiont endoparasitoid of tephritids, including Ceratitis capitata, which is one of the most important fruit pests worldwide. The objective of this study was to evaluate the effect of constant temperatures on the biology and development of the egg-adult period of T. giffardianus in larvae/pupae of C. capitata to construct a fertility life table. The study was carried out in climatic chambers at constant temperatures of 15, 20, 25, 30, and 35 ± 1°C, 70 ± 10% relative humidity and a photophase of 12 h. Complete egg and larval development occurred only at temperatures of 20, 25, and 30°C. The mean longevity of males and females was inversely proportional to temperature. The time of development of the pre-imaginal period was influenced by temperature and ranged from 41 days at 20°C to 11 days at 25°C. The best T. giffardianus performance occurred at 25°C when the intrinsic rate of increase was 0.21, the mean generation time was 20.43 days, the time required to double the population was 3.33 days, and the finite rate of population increase (λ) was 1.23. The results of this study provided information for the establishment of mass rearing and an evaluation of the adaptability of T. giffardianus to different environments, which is necessary for the use of this parasitoid in the biological control of tephritid pests, particularly C. capitata.

Analysis of the antennal transcriptome and odorant-binding protein expression profiles of the parasitoid wasp Encarsia formosa.

The parasitoid of whiteflies Encarsia formosa has been widely applied to reduce whitefly-mediated damage on vegetables and ornamental plants grown in greenhouses. Although its chemosensory behavior has been described, the mechanism by which E. formosa recognizes chemical volatiles at the molecular level remains unknown. In this study, we obtained 66,632 unigenes from antennae transcriptomic architecture of E. formosa, of which 19,473 (29.2%) were functionally annotated. All that matters is that we manually identified 39 odorant-binding proteins (OBPs) from above dataset, and further investigated the tissue and stage-specific expression profiles of all identified OBP genes by real-time quantitative PCR. Among these OBP genes, 32 were enriched in antennae, and 2 in body. In addition, 4 OBPs were highly expressed in pupae, and 32 in 6-hour-age adults after eclosion. In addition to identifying OBP genes from E. formosa, this study provides a molecular basis for further functional studies of OBPs and the interactions of hosts and parasitic wasps.

Germline mutagenesis of Nasonia vitripennis through ovarian delivery of CRISPR-Cas9 ribonucleoprotein.

CRISPR/Cas9 gene editing is a powerful technology to study the genetics of rising model organisms, such as the jewel wasp Nasonia vitripennis. However, current methods involving embryonic microinjection of CRISPR reagents are challenging. Delivery of Cas9 ribonucleoprotein into female ovaries is an alternative that has only been explored in a small handful of insects, such as mosquitoes, whiteflies and beetles. Here, we developed a simple protocol for germline gene editing by injecting Cas9 ribonucleoprotein in adult N. vitripennis females using either ReMOT control (Receptor-Mediated Ovary Transduction of Cargo) or BAPC (Branched Amphiphilic Peptide Capsules) as ovary delivery methods. For ReMOT Control we used the Drosophila melanogaster-derived peptide 'P2C' fused to EGFP to visualize the ovary delivery, and fused to Cas9 protein for gene editing of the cinnabar gene using saponin as an endosomal escape reagent. For BAPC we optimized the concentrations of protein, sgRNA and the transfection reagent. We demonstrate delivery of protein cargo such as EGFP and Cas9 into developing oocytes via P2C peptide and BAPC. Additionally, somatic and germline gene editing were demonstrated. This approach will greatly facilitate CRISPR-applied genetic manipulation in this and other rising model organisms.

Insights into the Interaction between the Monophagous Tephritid Fly Anastrepha acris and its Highly Toxic Host Hippomane mancinella (Euphorbiaceae).

Despite their enormous economic importance and the fact that there are almost 5000 tephritid (Diptera) species, fruit fly - host plant interactions are poorly understood from a chemical perspective. We analyzed the interactions among Anastrepha acris (a little studied monophagous tephritid) and its highly toxic host plant Hippomane mancinella from chemical, ecological and experimental perspectives, and also searched for toxicants from H. mancinella in the larval-pupal endoparasitoid Doryctobracon areolatus. We identified 18 phenolic compounds from H. mancinella pulp belonging to different chemical groups including phenylpropanoids, flavonoids, chalcones and coumarins. No traces of Hippomanin A were detected in larvae, pupae or A. acris adults, or in D. areolatus adults, implying that A. acris larvae can metabolize this toxicant, that as a result does not reach the third trophic level. We tested the "behavioral preference - lack of larval specialization-hypothesis" via feeding experiments with a larval rearing medium containing H. mancinella fruit (skin + pulp or pulp alone). The high toxicity of H. mancinella was confirmed as only two (out of 2520 in three experiments) A. ludens larvae (a polyphagous pest species that preferentially feeds on plants within the Rutaceae) survived without reaching the adult stage when fed on media containing H. mancinella, whereas A. acris larvae developed well and produced healthy adults. Together, these findings open a window of opportunity to study the detoxification mechanisms used by tephritid fruit flies.

Genome-wide identification and analysis of genes encoding cuticular proteins in the endoparasitoid wasp Pteromalus puparum (Hymenoptera: Pteromalidae).

The multifunctional insect cuticle serves as the exoskeleton, determines body shape, restricts water loss, provides attachment sites for muscles and internal organs and is a formidable barrier to invaders. It is morphologically divided into three layers, including envelope, epicuticle, and procuticle and is composed of chitin and cuticular proteins (CPs). Annotation of CPs and their cognate genes may help understand the structure and functions of insect cuticles. In this paper, we interrogated the genome of Pteromalus puparum, an endoparasitoid wasp that parasitizes Pieris rapae and Papilio xuthus pupae, and identified 82 genes encoding CPs belonging to six CP families, including 62 in the CPR family, 8 in CPAP3, 5 in CPF/CPFL, 2 low complexity proteins, 2 in TWDL, and 3 in Apidermin. We used six RNA-seq libraries to determine CP gene expression profiles through development and compared the cuticle hydrophobicity between the P. puparum and the ectoparasitoid Nasonia vitripennis based on GRAVY values of CPR sequences. In the Nasonia-Pteromalus comparison, we found in both N. vitripennis and P. puparum, the peak of their CPR hydrophobicity displayed at their pupal stage, whereas their adult stage showed the lowest level. Except at the adult stage, the CPR hydrophobicity in N. vitripennis is always higher than P. puparum. Finally, we identified three novel Apidermin genes, a family found solely in Hymenoptera and revealed a new sequence feature of this family. This new information contributes to a broader understanding of insect CPs generally.

Identification and characterization of miRNAs in an endoparasitoid wasp, Pteromalus puparum.

MicroRNAs (miRNAs) are a form of endogenous small noncoding RNAs that regulate protein-coding gene expression at the posttranscriptional level. So far, knowledge of miRNAs in parasitoids remains rudimentary. We investigated miRNAs in Pteromalus puparum, a pupal endoparasitoid wasp with genome and transcriptome sequences completed. In this study, we constructed eight small RNA libraries from selected developmental stages and genders: male embryos, male larvae, male pupae, male adults, mixed-sex embryos, mixed-sex larvae, mixed-sex pupae, and female adults. We identified 254 mature miRNAs with 5p/3p arm features originated from 75 known and 119 novel miRNA genes in P. puparum, 88 of which reside in 26 clusters. The miRNAs in more than half of the clusters exhibit a consistent expression pattern, indicating they were co-transcribed from a long transcript. Comparing miRNA expression in the eight libraries, we found that 84 mature miRNAs were differentially expressed between embryos and larvae, 20 between larvae and pupae, and 26 between pupae and adults. We found some miRNAs were differentially expressed between sexes in embryos (10), larvae (29), pupae (8), and adults (14). Target predictions resulted in 211,571 miRNA-mRNA interactions for 254 different mature miRNAs. These miRNAs may be involved in sexual and developmental regulation of gene expression.

Immune signaling pathways in the endoparasitoid, Pteromalus puparum.

Parasitoids serve as effective biocontrol agents for agricultural pests. However, they face constant challenges from host immune defense and numerous pathogens and must develop potent immune defense against these threats. Despite the recent advances in innate immunity, little is known about the immunological mechanisms of parasitoids. Here, we identified and characterized potential immune-related genes of the endoparasitoid, Pteromalus puparum, which act in regulating populations of some members of the Pieridae. We identified 216 immune-related genes based on interrogating the P. puparum genome and transcriptome databases. We categorized the cognate gene products into recognition molecules, signal moieties and effector proteins operating in four pathways, Toll, IMD, JAK/STAT, and JNK. Comparative analyses of immune-related genes from seven insect species indicate that recognition molecules and effector proteins are more expanded and diversified than signaling genes in these signal pathways. There are common 1:1 orthologs between the endoparasitoid P. puparum and its relative, the ectoparasitoid Nasonia vitripennis. The developmental expression profiles of immune genes randomly selected from the transcriptome analysis were verified by a quantitative polymerase chain reaction. Our work provides comprehensive analyses of P. puparum immune genes, some of which may be exploited in advancing parasitoid-based biocontrol technologies.

Biogenic amine biosynthetic and transduction genes in the endoparasitoid wasp Pteromalus puparum (Hymenoptera: Pteromalidae).

Biogenic amines (BAs), such as octopamine, tyramine, dopamine, serotonin, and acetylcholine regulate various behaviors and physiological functions in insects. Here, we identified seven genes encoding BA biosynthetic enzymes and 16 genes encoding BA G protein-coupled receptors in the genome of the endoparasitoid wasp, Pteromalus puparum. We compared the genes with their orthologs in its host Pieris rapae and the related ectoparasitic wasp Nasonia vitripennis. All the genes show high (>90%) identity to orthologs in N. vitripennis. P. puparum and N. vitripennis have the smallest number of BA receptor genes among the insect species we investigated. We then analyzed the expression profiles of the genes, finding those acting in BA biosynthesis were highly expressed in adults and larvae and those encoding BA receptors are highly expressed in adults than immatures. Octα1R and 5-HT7 genes were highly expressed in salivary glands, and a high messenger RNA level of 5-HT1A was found in venom apparatuses. We infer that BA signaling is a fundamental component of the organismal organization, homeostasis and operation in parasitoids, some of the smallest insects.

Genome-wide characterization and transcriptomic analyses of neuropeptides and their receptors in an endoparasitoid wasp, Pteromalus puparum.

In insects, neuropeptides constitute a group of signaling molecules that act in regulation of multiple physiological and behavioral processes by binding to their corresponding receptors. On the basis of the bioinformatic approaches, we screened the genomic and transcriptomic data of the parasitoid wasp, Pteromalus puparum, and annotated 36 neuropeptide precursor genes and 33 neuropeptide receptor genes. Compared to the number of precursor genes in Bombyx mori (Lepidoptera), Chilo suppressalis (Lepidoptera), Drosophila melanogaster (Diptera), Nilaparvata lugens (Hemiptera), Apis mellifera (Hymenoptera), and Tribolium castaneum (Coleoptera), P. puparum (Hymenoptera) has the lowest number of neuropeptide precursor genes. This lower number may relate to its parasitic life cycle. Transcriptomic data of embryos, larvae, pupae, adults, venom glands, salivary glands, ovaries, and the remaining carcass revealed stage-, sex-, and tissue-specific expression patterns of the neuropeptides, and their receptors. These data provided basic information about the identity and expression profiles of neuropeptides and their receptors that are required to functionally address their biological significance in an endoparasitoid wasp.

Genomic and transcriptomic analyses of glutathione S-transferases in an endoparasitoid wasp, Pteromalus puparum.

Pteromalus puparum is a gregarious pupal endoparasitoid with a wide host range. It deposits eggs into pierid and papilionid butterfly pupae. Glutathione S-transferases (GSTs) are a family of multifunctional detoxification enzymes that act in xenobiotic metabolism in insects. Insect genome projects have facilitated identification and characterization of GST family members. We identified 20 putative GSTs in the P. puparum genome, including 19 cytosolic and one microsomal. Phylogenetic analysis showed that P. puparum GSTs are clustered into Hymenoptera-specific branches. Transcriptomic data of embryos, larvae, female pupae, male pupae, female adults, male adults, venom glands, carcass, salivary glands, and ovaries revealed stage-, sex-, and tissue-specific expression patterns of GSTs in P. puparum. This is the most comprehensive study of genome-wide identification, characterization, and expression profiling of GST family in hymenopterans. Our results provide valuable information for understanding the metabolic adaptation of this wasp.

Age stage, two-sex life table of Habrobracon hebetor (Braconidae) on Spodoptera exigua (Noctuidae) reared on different sugar beet genotypes.

The present study was carried out to unveil interactive relevance among consecutive and alternate members of a tritrophic system comprised of sugar beet genotypes, beet armyworm, Spodoptera exigua (Hübner), and its parasitoid, Habrobracon hebetor (Say) using demographic parameters. To do so, H. hebetor was reared on S. exigua fed on 10 sugar beet genotypes, including SB26; SB27; SB29; SB33; SB34; (7112*SB36)*Sh-1-HSF-5; FC220; FC301; SBSI006; and HM 1339RZ in a growth chamber at 25 ± 1 °C, 60 ± 5% RH, and 16:8 (L: D) h photoperiod. The data was analyzed based on the age-stage, two-sex life table theory. Our results revealed high variation in duration of different life stages of H. hebetor on S. exigua reared on different sugar beet genotypes examined. The shortest (10.605 days) and longest (13.721 days) pre-adult period of H. hebetor was on S. exigua reared on SB26 and SB34, respectively. The longest (17.2 days) and shortest adult longevity (7.5 days) was on S. exigua reared on SB26 and SB27, respectively. The highest values of the intrinsic rate of increase (r) (0.209 day-1) and finite rate of increase (λ) (1.233 day-1) were observed on S. exigua reared on SB34 and their lowest values (0.159 and 1.172 day-1, respectively) were recorded on SB27. Resistant and susceptible genotypes to S. exigua, FC301 and (7112*SB36)*Sh-1-HSF-5, respectively, were only genotypes on which H. hebetor had greater and approximately equal r compared with S. exigua. This finding indicates high capability of H. hebetor to be successfully employed against S. exigua on sugar beet genotypes which are extremely different in resistance to this pest.

Temperature-dependent development, survival and reproduction of Apanteles hemara (Nixon) (Hymenoptera: Braconidae) on Spoladea recurvalis (F.) (Lepidoptera: Crambidae).

The temperature-dependent development of Apanteles hemara (Nixon), a larval endoparasitoid of the devastating amaranth pest Spoladea recurvalis (F.) was studied in the laboratory at six constant temperatures (10, 15, 20, 25, 30 and 35 °C), a photoperiod of 12L:12D and a relative humidity of 60-70%. Developmental time decreased significantly with increasing temperature within the range of 15-30 °C. The parasitoid's pupal mortality, successful parasitism rate, adult emergence rate and longevity, sex ratio and fecundity were affected by temperature. The population of A. hemara failed to develop at 10 and 35 °C. The development threshold (Tmin) and the thermal constant (K) were calculated by the linear model while the lethal temperature (Tmax) was determined by the Lactin-1 model. The estimated values of Tmin, Tmax and K by the two models were 10.3 °C, 35.0 °C and 185.18 DD respectively for the total immature development. The estimated value of the optimum temperature using the Taylor model was 30.8 °C. This is the first study to report on the effect of temperature on the developmental parameters of A. hemara giving an insight into its biology. The implications of these findings for the use of A. hemara in biological control are discussed.

Irradiation of early immature Anastrepha ludens stages for the rearing of Doryctobracon areolatus (Hymenoptera: Braconidae), a fruit fly parasitoid.

Doryctobracon areolatus is a native parasitoid of the Neotropical region that presents the highest percentages of natural parasitism of fruit flies of the genus Anastrepha. In the Moscafrut Program SADER-SENASICA, located in Metapa de Domínguez, Chiapas, Mexico, a laboratory colony of this species is maintained on Anastrepha ludens, the Mexican fruit fly, with the aim to scale the production of the parasitoid up to massive levels. In order to eliminate unwanted emergence of adult flies during the rearing process, this study evaluated the effect of irradiation (at doses of 20, 30, 40, and 50 Gy) applied to eggs, and first and second instar larvae of A. ludens; all irradiated stages were subsequently exposed as second instar larvae to adult females of D. areolatus. Irradiation did not affect the eclosion of A. ludens eggs but, at doses of 40 and 50 Gy, it did cause delayed larval development and pupation, as well as lower larval weight. Adult fly emergence was suppressed at all doses, except in eggs irradiated at 20 Gy. Doses of 20 and 30 Gy applied to the eggs and larvae did not affect the emergence, survival, fecundity or flight ability of the emerged parasitoids, but the second instar larvae were easily handled during the rearing process. Our results suggest that D. areolatus can be successfully produced in second instar larvae of A. ludens irradiated at 30 Gy.

Assessing the effects of Cry2Aa protein on Habrobracon hebetor (Hymenoptera: Braconidae), a parasitoid of Indian meal moth, Plodia interpunctella (lepidoptera: Pyralidae).

Transgenic crops express Cry proteins exhibit high resistant to target insect pests. When we evaluate the effects of Cry proteins on the parasitoid of target insect pest via tritrophic experiments (transgenic plant-target insect pest-parasitoid) host quality of parasitoids might decrease because of insecticidal protein ingestion, this would cause host-quality mediated effects and influence the accuracy of biosafety assessment. In the current study, high dose of Cry2Aa protein was injected into the hemolymph of Plodia interpunctella by microinjection, and the hemolymph was used as the carrier to deliver Cry protein to Habrobracon hebetor, which has been previously reported as an ectoparasitoid of P. interpunctella larval, in order to avoid the "host-quality mediated effects". Results showed that injected Cry2Aa remained at high concentration and bioactive in the hemolymph of P. interpunctella parasitized by H. hebetor, the hemolymph of P. interpunctella could be used as carriers of Cry protein to H. hebetor, and high dose of Cry2Aa have no negative impacts on the development time, weight of pupa, sex ratio, adults weight (male and female), adult longevity and fecundity, and the activity of stress-related enzymes of H. hebetor. However, the hemolymph of P. interpunctella injected into Galanthus nivalis agglutinin (the positive control) showed significant negative impact on these parameters measured in the present study of H. hebetor. This indicated that Cry2Aa protein had no detrimental effects on the biological parameters of H. hebetor measured in the current study. Meanwhile, this study provides a new method for the safety evaluation of the ectoparasitoids of target pest and might be expanded to the other species of ectoparasitoids of target insects of Cry proteins in biosafety risk assessment.

Tachinobia repanda (Hymenoptera: Eulophidae) From Egg Sacs of a Colonial Spider, Cyrtophora moluccensis (Araneae: Araneidae) in Papua New Guinea.

We report the discovery of the wasp Tachinobia repanda Boucek collected from egg sacs of the colonial spider Cyrtophora moluccensis (Doleschall) in Morobe Province, Papua New Guinea (PNG) by Lubin, Y.D. in 1980. This is the first record of T. repanda from egg sacs of a colonial spider. The likely host of this eulophid wasp was the larvae of a sarcophagid fly that parasitizes the egg sacs of these spiders. The 67 T. repanda collected were all females and varied little in body size. We suggest that this species is a gregarious hyperparasitoid.

Behavioral and Developmental Responses of Habrobracon hebetor (Hymenoptera: Braconidae) to Larvae of Helicoverpa armigera (Lepidoptera: Noctuidae) Inoculated With Various Concentrations of Bacillus thuringiensis var. kurstaki (Bacillales: Bacillacae).

Bacillus thuringiensis Berliner subsp. kurstaki (Btk) and Habrobracon hebetor Say are both biological control agents of Helicoverpa armigera Hubner. The present study evaluated their compatibility for combined application against this pest by examining the acceptability of Btk-inoculated hosts for H. hebetor females and testing for negative life-history impacts on developing progeny. Second-instar H. armigera larvae fed for 72 h on potted chickpea plants treated with three concentrations of Btk (LC15, LC35, and LC70) and were then used in bioassays of parasitoid development and parasitism behavior. Survival of parasitoids was significantly reduced, and immature development prolonged, on hosts fed chickpea plants treated with LC35 and LC70  Btk, but not on plants treated with LC15  Btk. Parasitoids failed to discriminate against hosts treated with LC15 or LC35  Btk in choice tests, but attacked fewer hosts treated with LC70  Btk, paralyzing and parasitizing more healthy hosts, and laying more eggs on them. In contrast, a no-choice test revealed that more hosts treated with LC35 and LC70  Btk were paralyzed compared with control or LC15-treated hosts, but the numbers of hosts parasitized and eggs laid did not vary among Btk treatments. Thus, females required an experience with healthy hosts, as they had in the choice test, to discriminate against diseased ones. We conclude that H. hebetor and Btk are compatible for joint application against H. armigera, which could potentially improve biological control of this pest.

Performance of Trichopria drosophilae (Hymenoptera: Diapriidae), a Generalist Parasitoid of Drosophila suzukii (Diptera: Drosophilidae), at Low Temperature.

Survival and parasitism activity of Trichopria drosophilae Perkins adults, a cosmopolitan parasitoid of Drosophila spp., were studied under laboratory conditions using five constant temperatures at the lower range known for this enemy, from 4 to 20°C in 4°C increments. Drosophila suzukii Matsumura, an invasive pest of small fruits, was used as a host. Commercially available adult parasitoids were provided with 1) food and D. suzukii pupae; 2) food and no D. suzukii pupae; 3) no food and no pupae. The results show that adult females of T. drosophilae lived longer than males, and both generally benefitted from food supply. The highest level of survival was observed between 8 and 12°C for fed insects, irrespective of whether they were offered host pupae or not. The absence of food led to the highest mortality, but the parasitoid demonstrated considerably resistance to prolonged starvation. Successful parasitism increased steadily with temperature and reached the highest value at 20°C. Conversely, D. suzukii emergence rate was high after exposure of pupae to parasitoids at 4°C, while pupal mortality increased strongly with temperature until 12°C. The findings indicate that T. drosophilae is well adapted to the relatively cold conditions experienced in early spring and in autumn or at high elevations, when the host pupae could be largely available. The long lifespan of the adults and the ability to parasitize the host at low temperature make T. drosophilae potentially useful for the biocontrol of D. suzukii.