Fruit and vegetable crops are affected by numerous arthropods, including aphids and thrips. Hoverfly adults are important pollinators, and their larvae are mainly aphid predators. Molecular studies on the stomach contents of larvae allowed to associate hoverflies with the consumption of other soft-bodied arthropods, including thrips, with few records found in Neotropical hoverfly species. Allograpta exotica (Wiedemann) (Diptera: Syrphidae), a species widely distributed in the Americas, from the USA to Argentinian Patagonia, has been associated with numerous crops mainly affected by aphids, and to a lesser extent with whiteflies. The objective of this work was to assess the consumption and preference rates of various instars of A. exotica as biocontrol agents for two major insect pests, Myzus persicae (Sulzer) (Hemiptera: Aphididae) and Frankliniella gemina (Bagnall) (Thysanoptera: Thripidae), under controlled laboratory conditions. Additionally, we morphologically characterized the three larval stages of A. exotica. We determined that all three instars of A. exotica consume both M. persicae and F. gemina, and that they kill more thrips than aphids. Still, A. exotica preferred M. persicae over F. gemina, even when the relative aphid availability decreased compared to F. gemina, although consumption of both prey types remained high. Interestingly, A. exotica second instars consumed four times more thrips than aphids. This study explored the potential use of one of the most common hoverfly species in fruit and vegetable crops as a biocontrol agent of aphids and thrips. Further laboratory and field studies should explore more deeply the potential of this Neotropical beneficial dipteran.

Drosophila suzukii (Matsumura) is an invasive pest mainly affecting berry and stone fruit crops worldwide. In Argentina, it inhabits fruit-growing regions. An eco-friendly management strategy involves biological control by using resident natural enemies, such as the Neotropical-native pupal parasitoid Trichopria anastrephae Lima (Ta). The study compared the host-killing capacity and the offspring reproductive success of two Ta lineages on the puparia of both D. suzukii (Ds) and D. melanogaster (Dm) in no-choice and choice tests under laboratory conditions. The host preference and host-switching behaviors were also assessed. One parasitoid lineage was reared on Ds (TaDs), and the second on Dm (TaDm). In no-choice tests, both Ta lineages performed similarly on both hosts regarding the percentage of killed hosts and parasitoid offspring survival. The host-killing ability of TaDm was only significantly lower when Ds was offered as a host, relative to Dm. In choice tests, Ta attacked mainly Ds at a 4–9 times Ds to Dm ratio, but at a 1.5–2 times Ds to Dm ratio, the host-killing ability was similar between both drosophilids. At an equal host ratio or higher Dm ratios, Ta preferred the native host. However, it was determined that Ta has the potential to parasitize the recently-introduced pest.

Understanding the seasonal dynamics inherent to non-crop host–fruit fly–parasitoid interactions is vitally important for implementing eco-friendly pest control strategies. This study assessed the abundance and seasonal infestation levels of three pest fly species, Ceratitis capitata (Wiedemann), Anastrepha fraterculus (Wiedemann), Drosophila suzukii (Matsumura), as well as the related saprophytic drosophilids, and their natural parasitism in a disturbed wild habitat characterized by non-crop hosts in northwestern Argentina over 40 months. Juglans australis Griseb (walnut), Citrus aurantium L. (sour orange), Eriobotrya japonica (Thunb.) Lindley (loquat), Prunus persica (L.) Batsch (peach), and Psydium guajava L. (guava) were sampled throughout their fruiting seasons. Fruits were collected from both the tree canopies and the ground. The most abundant puparia was A. fraterculus, followed by C. capitata and D. suzukii. Drosophila species from the D. melanogaster group were highly abundant only in fallen fruits. Spatiotemporal overlaps of different host fruit availability provided suitable sources for pest proliferation throughout the year. The populations of both invasive pests peaked from December to January, and were related to the highest ripe peach availability, whereas the A. fraterculus population peaked from February to April, overlapping with the guava fruiting period. The three pest fly species were parasitized mainly by three generalist resident parasitoids, which are potential biocontrol agents to use within an integrated pest management approach.

Native parasitoids are potential tools for the biological control of invasive exotic pests, such as the frugivorous flies spotted-wing drosophila, Drosophila suzukii Matsumura, and African fig fly, Zaprionus indianus Gupta (both Diptera: Drosophilidae). Following biological invasions, the establishment of exotic species may be restricted, among other things, by their susceptibility to native or established natural enemies. The Neotropical-native pupal endoparasitoid Trichopria anastrephae Costa Lima (Hymenoptera: Diapriidae), although primarily associated with hosts of the genus Anastrepha (Tephritidae), has also been described to attack Drosophilidae. There are few studies on the interaction between parasitoids native to Argentina and D. suzukii and/or Z. indianus. The present work evaluates the parasitism of T. anastrephae on both species of drosophilids under controlled conditions. Ten larvae (L3) of each host species were exposed separately to a couple of adult T. anastrephae for 72 h (n = 10). For both control and parasitoid treatment, 10 larvae (L3) of D. suzukii and Z. indianus were placed in 10 flasks (repetition) at the L3 stage. Host emergence, the infestation degree index (DI), and the parasitism success rate (SP) were calculated. Drosophila suzukii and Z. indianus emergence differed significantly in controlled conditions being 41% higher for Z. indianus than for D. suzukii. The DI was 100% in D. suzukii and 38% in Z. indianus, and the SP was 48% both in D. suzukii and in Z. indianus. These findings indicate that the native parasitoid T. anastrephae has a high potential as a biocontrol strategy against D. suzukii. In addition, the efficiency of T. anastrephae against Z. indianus, an invasive frugivorous widely spread in the Neotropical region, was evaluated for the first time.

The Asian Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) is a harmful invasive pest widespread throughout Argentinian fruit-producing regions. It coexists with both pests, the sub-Saharan African Ceratitis capitata (Wiedemann) and the Neotropical-native Anastrepha fraterculus (Wiedemann) (both Diptera: Tephritidae), in northwestern Argentina. The Neotropical-native parasitoid Ganaspis pelleranoi (Brethes) (Hymenoptera: Figitidae) is frequently found in non-crop fruit infested by those frugivorous dipterans. The northwestern Argentinian region is known for producing and exporting berries and citrus, which are affected by those pests. Thus, eco-friendly control strategies are under assessment. This study mainly assessed the potential of the G. pelleranoi population lineage from Tucuman (Gp(Tuc)) as a D. suzukii biocontrol agent. First, both the host-killing effectiveness and the reproductive success of Gp(Tuc) on larvae of D. suzukii, C. capitata, A. fraterculus, and Drosophila melanogaster Meigen were compared in no-choice tests under laboratory conditions. Then, the Gp(Tuc) host preference was evaluated in dual-choice tests (D. suzukii vs. C. capitata or A. fraterculus) under laboratory and field conditions. Naive parasitoid females were allowed to forage for 8 h on screen-covered Petri dishes filled with host larvae under laboratory conditions and for 48 h on peaches inoculated with host larvae under field conditions. Host puparia dissections were performed to determine the number and condition of parasitoid eggs, first and second instars, such as alive/dead, without/with melanization process, and proportions of parasitized, superparasitized, and dead puparia. Drosophila suzukii was not a suitable host for the successful development of Gp(Tuc) immature stages as they did not overcome the host's immune system. However, Gp(Tuc) performed efficiently regarding D. suzukii mortality, but parasitoid specificity was restricted to both tephritid species as only thriving offspring were achieved from them. Interestingly, the effectiveness of Gp(Tuc) on D. suzukii increased when it co-occurred with C. capitata instead of A. fraterculus, the preferred host.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), world-renowned as spotted-wing drosophila, is an invasive pest mainly affecting healthy, soft and stone fruit crops throughout Argentinian fruit-growing regions. Natural environments overgrown by exotic feral host plants apparently favour D. suzukii proliferation. This is common in the subtropical northwestern Argentina's berry-producing region. An assemblage of resident parasitoid species has been associated with D. suzukii in crop and non-crop areas of Tucumán, the Argentina's leading berries producer and exporter. Consequently, the hypothesis that the combined action of two pupal parasitoid species, Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) and Trichopria anastrephae Lima (Hymenoptera: Diapriidae), occurring in non-crop fruit areas, has a significant impact on D. suzukii natural regulation in such invaded habitats was tested. A survey of D. suzukii puparia from both feral peach [Prunus persica (L.) Batsch] (Rosaceae) and guava (Psydium guajava L.) (Myrtaceae) fallen fruits and soil surrounding them was performed in a wilderness area of Tucumán. Abundance of D. suzukii and associated parasitoids, and parasitism levels were assessed. Whole of 3437 D. suzukii puparia were recovered; 78% and 22% were surveyed from fruits and soil underneath the fruit, respectively. Tested fruits are important D. suzukii multiplying hosts. Both P. vindemiae and T. anastrephae accounted for 99.8% of total parasitoid individuals. Pupal parasitoids contribute to the D. suzukii natural mortality, as they killed a quarter of all puparia. Mostly T. anastrephae foraged on host puparia located in the fruit and P. vindemiae in both microhabitats. This information supports an augmentative biological control strategy in non-crop areas.

Syrphid larvae are effective biological control agents in numerous crops due to their voracity, and they are used in both augmentative and conservation-based strategies within horticultural systems. This study conducted laboratory trials to ascertain the predation rate of Allograpta exotica (Wiedemann) (Diptera: Syrphidae) on Chaetosiphon fragaefolii (Cockerell) (Hemiptera: Aphididae) and to compare it with the predation rate on Aphis gossypii Glover (Hemiptera: Aphididae), another significant aphid species affecting strawberries. Additionally, field trials were conducted to assess the reduction in the field population of C. fragaefolii achieved by A. exotica within strawberry crops. We observed a significant increase in the number of aphids consumed by a larva as it progressed from first-instar larvae (L1) to third-instar larvae (L3). Specifically, the mean aphid consumption by second-instar larvae (L2) was nearly 11 times higher for C. fragaefolii and 10 times higher for A. gossypii compared to L1. Furthermore, the consumption rate of L3 larvae was approximately 2 times higher for both aphid species compared to L2. In laboratory conditions, A. exotica larvae significantly reduced the number of both aphid species, but the control on A. gossypii was higher than on C. fragaefolii. The results of the field experiment demonstrated that the predatory hoverfly A. exotica significantly reduced the numbers of C. fragaefolii compared to the control treatment, highlighting its potential as a promising biological control agent in strawberry crops.

The Southeast Asian–native Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), also known as “spotted-wing Drosophila,” is one of the most globally invasive agricultural species. Although D. suzukii is a pest spread throughout all the Argentinian fruit-growing regions, few information has been published on its impact on local fruit production. Parasitoid species associated with D. suzukii in Argentina belong to Pteromalidae (Chalcidoidea), Diapriidae (Diaprioidea), both attacking host pupae, and Figitidae (Cynipoidea), which attack host larvae. Nine Eucoilinae (Figitidae) species, belonging to Dicerataspis , Dieucoila , Euxestophaga , Ganaspis , Hexacola , and Leptopilina genera, have been associated with D. suzukii in Argentina. Ceratitis capitata (Wiedemann), commonly known as “medfly,” is native to Africa and has a worldwide distribution, covering many tropical, subtropical, and temperate regions. In Argentina, C. capitata has been associated with several native hymenopterous parasitoids belonging to Braconidae (Ichneumonioidea), Eulophidae (Chalcidoidea), Pteromalidae, Diapriidae, and Figitidae families. Only two eucoline species, Ganaspis pelleranoi (Brèthes) and Leptopilina haywardi (Blanchard) have been related to medfly in Argentina. We report new trophic associations between the parasitoids Dicerataspis grenadensis Ashmead and Leptopilina boulardi (Barbotin, Carton and Kelner-Pillault) and D. suzukii , and between the parasitoid Odontosema albinerve Kieffer and C. capitata , after surveys conducted in Tucumán, northwestern Argentina. An annotated checklist and a taxonomic key of Eucoilinae associated with both invasive pests, in Argentina, are also provided.

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), commonly known as spotted-wing drosophila or SWD, is an invasive, severe, and damaging pest, which is able to inflict huge economic losses on soft thin-skinned fruits worldwide. Argentina was not excluded from the rapid invasion of this new and aggressive pest. Berries and cherries are among the most economically important fruits, showing an increasing demand from both domestic and export markets, which make necessary the application of effective and early protection measures. Although SWD is currently established almost everywhere in Argentina, the scarcity of research on and rapid regulatory actions against this pest have probably contributed to its fast spread throughout the country. In view of that, the article reviews first the current threat status of SWD in Argentina, provides summarized information on crop and non-crop host fruits, seasonal variation and population dynamics, resident natural enemy assemblages, and describes control actions implemented to date. Finally, the need to focus local control actions within an integrated national SWD management program is emphasized. The development and application of complementary eco-friendly strategies, such as Sterile Insect Technique, biological control, mass trapping, and the use of innovative lactone-derived synthetic insecticides with extremely low toxicity for SWD parasitoids, in environmentally distinguishable Argentinian regions is also highlighted.

Understanding the mechanisms associated with the coexistence of competing parasitoid species is critical in approaching any biological control strategy against the globally invasive pest spotted-wing drosophila (=SWD), Drosophila suzukii (Matsumura). This study assessed the coexistence of two resident pupal parasitoids, Trichopria anastrephae Lima and Pachycrepoideus vindemiae Rondani, in SWD-infested fruit, in disturbed wild vegetation areas of Tucumán, northwestern Argentina, based on niche segregation. Drosophilid puparia were collected between December/2016 and April/2017 from three different pupation microhabitats in fallen feral peach and guava. These microhabitats were "inside flesh (mesocarp)", "outside flesh", but associated with the fruit, and "soil", i.e., puparia buried close to fruit. Saprophytic drosophilid puparia (=SD) belonging to the Drosophila melanogaster group and SWD were found in all tested microhabitats. SD predominated in both inside and outside flesh, whereas SWD in soil. Both parasitoids attacked SWD puparia. However, T. anastrephae emerged mainly from SD puparia primarily in the inside flesh, whereas P. vindemiae mostly foraged SWD puparia in less competitive microhabitats, such as in the soil or outside the flesh. Divergence in host choice and spatial patterns of same-resource preferences between both parasitoids may mediate their coexistence in non-crop environments. Given this scenario, both parasitoids have potential as SWD biocontrol agents.

Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), known as Medfly, is a severe agricultural invasive pest in Argentinian fruit-producing regions. The native habitat disturbance and introduction and spread of exotic host plants strongly favored Medfly proliferation. This scenario is common throughout the northern subtropical citrus-growing region. Environmentally friendly strategies to suppress Medfly populations by the National Fruit Fly Control and Eradication Program have currently been taken. One of these actions involves augmentative biological control through releases of the exotic parasitoid Diachasmimorpha longicaudata (Ashmead) (Hymenoptera: Braconidae). Consequently, the hypothesis that the effectiveness of D. longicaudata females, from two different population lines, in controlling Medfly larvae progressively increases as the density of released females increases was tested. One parasitoid line derives from larvae of a biparental Medfly strain. The other hails from irradiated larvae of the genetic sexing Temperature Sensitive Lethal Vienna-8 medfly strain reared at the “BioPlanta San Juan” biofactory. Parasitoids foraged for 24 h on peaches artificially inoculated with naked lab-reared biparental Medfly larvae. Peaches were placed near the roof or on the ground in field cages. Five treatments (20, 40, 80, 160, and 320 females released) and a control (no parasitoids) for each population line were carried out throughout summer and autumn 2016. Host density (200 larvae) remained constant. At 320 released parasitoid females, both D. longicaudata population lines highly increased the Medfly mortality in both testing seasons, and foraged skillfully on peaches at both fruit height levels. These data encourage the application of augmentative biological control against Medfly.

Ceratitis capitata (Wiedemann) and Drosophila suzukii (Matsumura) are two severe invasive pests widespread in all Argentinean fruit-producing regions. Both coexist with the Neotropical pest Anastrepha fraterculus (Wiedemann) in northern Argentina. The northwestern region shelters major soft fruit and Citrus producing and exporting industries, which are heavily affected by these dipterans. Eco-friendly strategies are under assessment in Argentina. This study mainly assessed D. suzukii, C. capitata, and A. fraterculus temporal abundance variations and their natural parasitism levels on a 1.5-ha-patch of feral peach trees within a disturbed secondary subtropical rainforest of northwestern Argentina. Fly puparia were mainly collected from the soil under fallen peach. Sampling was performed over three peach fruiting seasons. The most abundant pest species was C. capitata. Drosophila suzukii was only found in the last collecting period, but outnumbered A. fraterculus. Natural parasitism distinctly affected the temporal abundance of these dipterans: it significantly depressed C. capitata abundance in last sampling weeks, it did not substantially affect D. suzukii abundance, but it increased synchronously with the increase in the A. fraterculus abundance. Parasitism on C. capitata was mostly exerted by a combination of both a cosmopolitan pupal and a native larval parasitoid, while A. fraterculus was mainly parasitized by two indigenous larval parasitoids. Only three resident pupal parasitoids were associated with D. suzukii, of which the cosmopolitan Pachycrepoideus vindemiae Rondani (Hymenoptera: Pteromalidae) was the most significant. Data on the resident parasitoid impact are relevant for designing biocontrol strategies in noncrop habitats.

Studies were conducted to broaden the current knowledge on seasonality, richness, abundance, and role of syrphids flies in the greenhouse pepper agroecosystem (GPA) in northwestern Argentina. In the GPA, a great richness (54 species) and abundance (517 individuals) of syrphids were found within Syrphinae (40 species; 443 individuals) and Eristalinae (14 species; 74 individuals) subfamilies. Besides, three species, Ocyptamus dimidiatus , O. gastrostactus and Toxomerus watsoni , were recorded for the first time in Argentina, and 12 species were recorded for the first time in Tucumán, expanding their geographical distribution to northwestern Argentina. Syrphid population tend to increase in spring and autumn. The environment occupation by different species showed remarkable differences since 41 were found in an open field, three in the greenhouse, and 10 in both environments. The richness and biodiversity were higher at the open field than in the greenhouse, however, these greenhouse species are important as biological control agents (BCA). Among them, the most abundant were Allograpta exotica , A. obliqua , T. duplicatus , Toxomerus sp. 1, O. dimidiatus and O. zoroaster , whose larvae were found feeding on pepper pests such as whiteflies and aphids. New plant-pest-predator associations were established, involving pepper, weeds, aphids, whiteflies, and syrphids. Four collection methods: Malaise trap, sweep net, infested plant tissues, and McPhail trap contributed to 59.2%, 70.4%, 8.6%, and 7.4% of total syrphid richness, respectively. Based on abundance, distribution in the GPA, and direct involvement in pepper pest control, A. exotica , A. obliqua , T. duplicatus, and Toxomeru s sp.1 can be used as BCA for the control of whiteflies and aphids in GPA.

ABSTRACT Heterospecific and conspecific host discrimination, and super- and multiparasitism by the neotropical figitid Ganaspis pelleranoi were determined using 6-d-old Ceratitis capitata larvae in choice trials, where alternatives such as hosts previously parasitised by the exotic braconid Diachasmimorpha longicaudata, or by conspecific G. pelleranoi, and/or unparasitised hosts were available. Choice assays involved both experienced and naïve figitid females, previously host-exposed and non-host-exposed, respectively. Multiparasitism was mainly avoided if the G. pelleranoi female had a choice between unparasitised and parasitised larvae. Heterospecific host discrimination was highly improved by ovipositional experience. A very limited number of experienced G. pelleranoi females visited, probed, or oviposited host larvae previously parasitised by D. longicaudata. Only 2% of figitid adults were recovered from puparia resulting from larvae previously parasitised by D. longicaudata and exposed to naïve females. No figitid adults were recovered in those treatments involving experienced females. Latency and host examination data, number of visits, probing and oviposition’s activities showed that experienced G. pelleranoi female has a higher propensity to forage unparasitised host larvae rather than larvae previously parasitised by conspecific females. Self-superparasitism was greater than conspecific superparasitism when figited females had to choose between unparasitised and conspecific parasitised larvae. The ability of G. pelleranoi females to discriminate previously parasitised medfly larvae suggests low levels of both heterospecific and conspecific competition. Combined releases of D. longicaudata and G. pelleranoi in Argentinean fruit-growing regions could be a more advantageous alternative than individual species releases.

Drosophila suzukii (Matsumura) (Diptera Drosophilidae), spotted-wing Drosophila (SWD), has recently invaded Argentina, spreading very quickly through different fruit-growing regions. Because of the risk represented by SWD for the national berry industry, it is necessary to develop biological alternatives for its control. Determine the presence of native natural enemies associated with SWD is important to develop biological control programs against this pest. In this study, we present the results of a field survey aimed to collect and identify Hymenoptera parasitoids associated with SWD in organic raspberry crops. We found an almost irrelevant parasitization rate on SWD pupae. The few parasitoids collected were identified as a new species of Dieucoila Ashmead, Dieucoila octoflagella Reche sp. n., which is here described and characterized in comparison with other species in the genus Dieucoila.

New records of the ectoparasitoid Pachycrepoideus vindemmiae (Rondani) (Hymenoptera: Pteromalidae) associated with Drosophila suzukii Matsumura (Diptera: Drosophilidae) in the provinces of Tucumán, Río Negro and Neuquén are cited. Detections occurred in blueberry, raspberry and cherry crops. The records from Río Negro and Neuquén constitute the southernmost report of the species. Diagnosis and prevalence of the parasitoid are briefly discussed