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Background The Toad grasshopper pest, Bufonacris claraziana (Saussure) (Orthoptera: Tristiridae) is an endemic species of the Argentine Patagonia region. Among the Tristiridae family, it is the only species recognized as harmful to agricultural and livestock activities in the country. Outbreaks of B. claraziana have become a recurring phenomenon in the recent years, affecting different areas of the Patagonian provinces. The aim of this study was to evaluate, as laboratory bioassays, the mortality in young nymphs of this species treated with bait formulations of the entomopathogenic fungus Beauveria bassiana (Hypocreales: Clavicipitaceae). Results The two treatments performed, one of them (I) with conidia of B. bassiana only and the other (II) with conidia of B. bassiana plus canola oil as phagostimulant, produced significantly higher mortality than the control ( p  < 0.05). At 10 days from the start of the bioassay, the mortality registered in the treatment II (53.33%) was higher than that in the treatment I (23.33%) ( p  < 0.05). This difference was similar at 15 days post-treatment, mortality reached in treatment II (93.33%) higher than in treatment I (73.33%). Conclusions Results demonstrated that the combination of canola oil with wheat bran makes the bait with conidia of B. bassiana more attractive for nymphs of B. claraziana , enhancing mortality over a shorter interval of time.

Worldwide declines in critical hymenopteran pollinators, such as bumble bees and honey bees, in recent decades have sparked a surge in research aimed at identifying the factors behind these declines. Among the suspected contributors, infectious diseases have garnered significant attention. In this context, we conduct a comprehensive review of the potential impact of naturalized Palearctic exotic bumble bee species, specifically Bombus terrestris and Bombus ruderatus , on the occurrence of Apicystis bombi in southern South America. Apicystis bombi is a unique apicomplexan protist that belongs to the neogregarines, which as a group exhibit relatively high virulence towards a range of insects. Our review encompasses the available information on its morphology, molecular characteristics, pathology, host range, and geographic distribution. Additionally, we explore three plausible hypotheses, each not necessarily exclusive of the others, in an effort to shed light on the occurrence of A. bombi in South America. These hypotheses include the two classically accepted, but less supported in view of current data (entry via B. terrestris , entry via B. ruderatus ), and one postulated for the first time here with arguably better support (pre-existing presence before the introduction of B. terrestris and B. ruderatus , plus the possibility of multiple Apicystis species coexisting). We aim for this review to stimulate interest in this relatively obscure parasitic microbe that affects crucial insect pollinators.

In the first half of the twentieth century, the South American Locust (SAL), Schistocerca cancellata (Serville, 1838), was a major pest of agriculture in Argentina, Bolivia, Paraguay, Uruguay, and Brazil. From 1954–2014, a preventive management program appeared to limit SAL populations, with only small- to moderate-scale treatments required, limited to outbreak areas in northwest Argentina. However, the lack of major locust outbreaks led to a gradual reduction in resources, and in 2015, the sudden appearance of swarms marked the beginning of a substantial upsurge, with many swarms reported initially in Argentina in 2015, followed by expansion into neighboring countries over the next few years. The upsurge required a rapid allocation of resources for management of SAL and a detailed examination of the improvements needed for the successful management of this species. This paper provides a review of SAL biology, management history, and perspectives on navigating a plague period after a 60-year recession.

The worldwide spread of diseases is considered a major threat to biodiversity and a possible driver of the decline of pollinator populations, particularly when novel species or strains of parasites emerge. Previous studies have suggested that populations of introduced European honeybee (Apis mellifera) and bumblebee species (Bombus terrestris and Bombus ruderatus) in Argentina share the neogregarine parasite Apicystis bombi with the native bumblebee (Bombus dahlbomii). In this study we investigated whether A. bombi is acting as an emergent parasite in the non-native populations. Specifically, we asked whether A. bombi, recently identified in Argentina, was introduced by European, non-native bees. Using ITS1 and ITS2 to assess the parasite's intraspecific genetic variation in bees from Argentina and Europe, we found a largely unstructured parasite population, with only 15% of the genetic variation being explained by geographic location. The most abundant haplotype in Argentina (found in all 9 specimens of non-native species) was identical to the most abundant haplotype in Europe (found in 6 out of 8 specimens). Similarly, there was no evidence of structuring by host species, with this factor explaining only 17% of the genetic variation. Interestingly, parasites in native Bombus ephippiatus from Mexico were genetically distant from the Argentine and European samples, suggesting that sufficient variability does exist in the ITS region to identify continent-level genetic structure in the parasite. Thus, the data suggest that A. bombi from Argentina and Europe share a common, relatively recent origin. Although our data did not provide information on the direction of transfer, the absence of genetic structure across space and host species suggests that A. bombi may be acting as an emergent infectious disease across bee taxa and continents.

Gregarina ronderosi is an obligate parasite of the digestive tract of the pest grasshopper Dichroplus elongatus. It is one of only two eugregarines of Argentine grasshoppers described with their complete life cycles. Given the lack of knowledge regarding fundamental epizootiologic aspects of eugregarine infections in Argentine grasshoppers, the objective was to initiate the recording of the geographic distribution of G. ronderosi in the Pampas region, its natural prevalence, and the intensity of infections under natural conditions. To this end, 4084 individuals of D. elongatus were collected at 42 localities in the Pampas region between 2008 and 2012. Mean prevalence of G. ronderosi for all localities with presence (17 localities) was 29.7 ± SE 6.6% (n = 1071). Infected individuals (n = 396) were categorized according to infection intensity: three (0.8%) had very heavy infections, 80 (20%) showed heavy infections, 210 (53%) moderate, and 103 (26%) light ones. The known geographic distribution of G. ronderosi was expanded, high prevalence events suggesting the occurrence of epizootics were recorded, and intense infections categorized as very heavy and heavy were detected under natural conditions for the first time.

Both the identity and prevalence of parasitoid dipterans associated with bumble bees (Bombus spp.) in southern South America are little known. Between 2009 and 2017, a total of 2978 bumble bees were individually collected in 63 localities from 11 provinces of the country. After dissections, the presence of parasitoids was observed in the native bumble bees Bombus pauloensis, B. bellicosus, B. opifex, and B. brasiliensis, plus in the exotic invasive species B. terrestris. A combination of both morphological and molecular analysis based on the COI gene allowed the isolation of two species of Physocephala (Conopidae) and one of Helicobia (Sarcophagidae), expanding their host range and geographic distribution. The second instar larva of Helicobia aurescens is described.

Siguiendo el procedimiento estándar de inocular por vía oral ninfas de tercer estadio con 105 esporos cada una, se determinó la infectividad del microsporidio Paranosema locustae (Canning), un patógeno desarrollado para el control biológico a largo plazo de tucuras, respecto del Romaleidae Tropidacris collaris (Stoll), especie que en años recientes ha demandado una mayor aplicación de insecticidas para su control. La proporción de insectos que desarrolló infección fue baja (38 %; n = 50), la producción de esporos en ellos fue casi nula (sólo dos infecciones traza) y no se observaron signos o síntomas típicos asociados a infecciones fuertes. Dado que una alta producción de unidades infectivas transmisibles (esporos) es normalmente necesaria para la persistencia de una enfermedad infecciosa (con transmisión horizontal predominante) en la población del huésped, se estima que P. locustae no sería una alternativa eficaz para el control de T. collaris. Following the standard procedure of orally inoculating third-instar nymphs with 105 spores each, the infectivity of the microsporidium Paranosema locustae (Canning), a pathogen developed for the long-term control of grasshoppers, to Tropidacris collaris (Stoll), was determined. In recent years, T. collaris has demanded a heavier use of insecticides for its control. The proportion of insects that developed infection was low (38 %; n = 50), the level of spore production was almost nil (only two trace infections), and typical signs or symptoms associated with heavy infections were not observed. Since a high production of infective transmissible units (spores) is normally needed for an infectious disease with predominant horizontal transmission to be able to persist in the population of the host, it is inferred that P. locustae would not be an efficacious alternative for the control of T. collaris.

Se realizó el seguimiento en laboratorio de cinco cohortes de Baeacris pseudopunctulatus Ronderos, con el objetivo de conocer algunos aspectos fundamentales su biología y reproducción bajo condiciones controladas (30º C, 14L: 10O, 40% HR). Se registraron 5 estadios ninfales. La duración del ciclo ninfal fue de 30,14 ± 0,85 días. La duración promedio de las cohortes fue de 10,66 ± 1,7 semanas. El número promedio de posturas por hembra fue de 3,56 ± 0,52. El número promedio de huevos por postura fue de 15,5 ± 0,6, con un mínimo de 10 huevos y un máximo de 22. La fecundidad promedio (número de huevos/hembra) fue de 46,03 ± 6,84. La tasa de oviposición fue de 1,20 ± 0,21 huevos/hembra/día. Five cohorts of Baeacris pseudopunctulatus Ronderos were monitored under controlled conditions (30º C, 14L:10D, 40% RH) in order to determine some fundamental aspects of its biology and reproduction. Five nymphal instars were recorded. The observed developmental time in nymphs was 30,14 ± 0,85 days. Mean duration of cohorts was 10,66 ± 1,7 weeks. Mean number of egg-pods per female was 3,56 ± 0,52, and mean number of eggs per pod was 15,5 ± 0,6, with a minimum of 10 and a maximum of 22. Mean fecundity (number of eggs per female) was 46,03 ± 6,84. The egg-laying rate was 1,20 ± 0,21 eggs/female/day.

During surveys for the detection of protists associated to Apidae in the Pampas region, biconcave oval spores, and spore clumps were observed in the Malpighian tubules of honeybees from Dufaur, Saavedra county, southwestern Buenos Aires province. Mature spores measured 4.8 ± 0.05 x 2.4 ± 0.03 μm, and mean spore load was 5.71 ± 1.49 x 106 per honeybee. Detections were from July to October 2006, and prevalence in positive colonies ranged from 1 to 16.7%. Morphology of the spores, the site of development, and the identity of the host species suggest that the isolated microorganism belongs to the genus Nephridiophaga and would be N. apis Ivanić, the type species, knowledge on which is extremely limited. The finding constitutes the first record of a nephridiophagid in honeybees outside of Europe.

In this study, the effects of strain Beauveria bassiana (LPSC 1067) as an endophyte in corn plants on consumption, fecundity, and food preference of Dichroplus maculipennis were examined. We observed that the daily consumption by grasshoppers fed with control plants was almost twice that of those that were fed treated plants. Significant differences in fecundity of grasshoppers that were fed with treated plants compared with those that only fed on control plants were also observed. The number of eggs laid per female fed with control plants was 27.2, while the number of eggs laid per female that were fed during 15 d with treated plants was 17.7. Similar results were observed when the number of embryonated eggs was evaluated. The highest number of embryonated eggs were recorded in those females that only fed on control plants (96%) while fewer embryonated eggs were recorded in grasshoppers fed for 15 d with treated plants only (25%). In relation to food preference the average consumption rate for D. maculipennis females on control corn plants was 303.8 ± 24.5 mg while it was only 25 ± 2.1 mg on plants treated with B. bassiana as an endophyte. In summary, we observed that B. bassiana as a corn plant endophyte negatively affected the daily consumption rate, fecundity and food preference of D. maculipennis.