Neotropical Research Articles

Long-term contamination by non-native fish assemblages in a Neotropical floodplain.

Biological invasions are a major threat to biodiversity in species-rich regions. Therefore, it is important to understand mechanisms behind the long-term establishment of non-native fish species in aquatic environments in the Neotropical region. Here, we associated fish biomass, species richness, and the proportion of non-native species (contamination and Kempton's indices) to quantify the non-native pressure over fish biodiversity in lakes and rivers of the Parana River floodplain, seasonally, from 2000 to 2017. We divided species into native and non-native assemblages sampled in spatio-temporal gradients. Temporal trends were examined using linear regressions and generalised additive models. Fish biomass in gillnets increased for both native and non-native fish species, but their Kempton indices were inversely correlated. Extinction of native species occurred locally with biotic differentiation of non-native species in lakes, rivers, and ecosystem contamination. A constant increase in fish biomass resulted in overwhelming biodiversity of non-natives at the end of the time series evaluated. Native biotic resistance to introductions was not detected in deterministic trends. The observed patterns were consistent with previous studies showing native biotic homogenisation and extinction of species in response to biological invasions, landscape fragmentation, and riverine impoundments. Increases in abundance and species richness of non-native fish were the biodiversity drivers that resulted in non-native species outweighing native species in the Parana floodplain.

Molecular identification of Fusarium species in commercial vanilla and crop wild relatives in Colombia.

Vanilla is an economically important crop for low-lying humid tropical regions, but cultivated plants face serious phytosanitary problems. Fusarium wilt is a devastating disease affecting vanilla crops, caused by the fungal pathogens Fusarium oxysporum f. sp. vanillae (Fov) and F. oxysporum f. sp. radicis-vanillae (Forv), part of the F. oxysporum species complex (FOSC). We characterized 29 fungal isolates from a vanilla crop and crop wild relatives (CWR) using molecular (EF1-α and ITS-rRNA loci) and morphological traits. Fusarium was the predominant genus, followed by Colletotrichum and Clonostachys. Four Fusarium species were identified: F. oxysporum (37.9%), Fusarium solani (20.7%), Fusarium pseudocircinatum (13.8%) and Fusarium concentricum (10.3%). The latter three species were isolated only from CWR and may represent latent pathogens. Fov was isolated from both the crop and CWR, while a Forv-affiliated isolate was also found in a vanilla crop, marking the first report in the neotropical region. The EF1-α locus provided greater genotype resolution, as well as having reference sequences for Forv. However, the fungal barcode ITS locus is widely applied. We recommend the continued use of both loci for Fusarium diagnosis in vanilla to facilitate early detection and the development of effective integrated crop management strategies.

Unravelling the diversity of Posthodiplostomum Dubois, 1936 (Trematoda: Diplostomidae) in fish-eating birds from the Neotropical region of Mexico, with the description of a new species.

Adults of the genus Posthodiplostomum, Dubois, 1936 are parasites of fish-eating birds, mainly of the family Ardeidae, and are globally distributed. The genus currently comprises 35 species, although recent molecular evidence has shown that the diversity of the genus is underestimated since several candidate species have been recognized. In the Neotropical region of Mexico, at least 6 Posthodiplostomum lineages have been detected with metacercaria stages recovered from unrelated fish hosts. Here, we obtained adult specimens of Posthodiplostomum from 6 fish-eating birds representing 2 families (Butorides virescens, Ardea herodias, Nycticorax nycticorax, Tigrisoma mexicanum – Ardeidae, and Rynchops niger and Leucophaeus atricilla – Lariidae) from 4 localities in southern Mexico. Specimens were sequenced for 2 nuclear (28S and ITS1–5.8S–ITS2) and 1 mitochondrial (cox1) molecular marker. Phylogenetic analyses allowed us to link metacercariae and adult specimens and recognized a lineage, which was described morphologically. The new species can be distinguished from its congeners by its prosoma morphology and body size; this is the first described species in the Neotropical region of Mexico. Additionally, new host and locality records for P. macrocotyle and P. pricei are presented, expanding their geographical distribution range in the Americas.

Henneguya patriciai n. sp. (Cnidaria: Myxosporea) parasitizing Leporinus friderici (Bloch 1794) from Tartarugalzinho river, eastern Amazon.

The Amazon basin has the largest number of fish in the world, and among the most common fishes of the Neotropical region, the threespot (Leporinus friderici) is cited, which in relation to its microparasitic fauna, has described only 1 species of the genus Henneguya, Henneguya friderici. The Myxozoa class is considered an obligate parasite, being morphologically characterized by spores formed by valves connected by a suture line. This study describes a new species of Henneguya sp. in the Amazon region for L. friderici. This parasite was found in the host's pyloric caeca and caudal kidney, with mature spores with a total spore length of 38.4 ± 2.5 (35.9–40.9) μm; the spore body 14.4 ± 1.1 (13.3–15.5) μm and 7.3 ± 0.6 (6.7–7.9) μm wide. Regarding its 2 polar capsules, they had a length of 5.1 ± 0.4 (4.7–5.5) μm and a width of 2.0 ± 0.1 (1.9–2.1) μm in the same pear-shaped, and each polar capsule contained 9–11 turns. Morphological and phylogenetic analyses denote that this is a new species of the genus Henneguya.

Establishment of a cell culture from the frog Leptodactylus fuscus as a model for (eco)toxicological assays

Leptodactylus fuscus is a frog species widely distributed in the Neotropical region, occurring in several biomes, which makes it a potential biomonitor of environmental conditions. To advance the establishment of this species in this field, we developed a fibroblast-like cell line derived from the digits of the forelimbs (LFUfd) and evaluated its response to possible environmental stressors. An adult male L. fuscus was collected, anesthetized, and euthanized with eugenol. Digits from the forelimbs were extracted, decontaminated, and dissociated. Cells were plated and cultivated in vented flasks with DMEM/F12+GlutaMAX medium and 20% FBS at 28 °C. On the 15th passage, we made the chromosome preparations, where we placed them on slides and stained them with Giemsa for karyotype analysis. The cellular response to multiple stressors (Temperature, Hydrogen Peroxide, and Aluminum) was evaluated through the MTT assay. The temperature test evaluated two groups (28 °C and 37 °C for 24 h). The effect of hydrogen peroxide (H2O2) was analyzed by treatment for 1 h at 28 °C in different concentrations (control, 2 μM, 20 μM, 50 μM, 100 μM and 200 μM). The effects of aluminum have been tested at three concentrations (0.5 mg/L, 1 mg/L, and 10 mg/L). The karyotype obtained showed 22 chromosomes, according to the description of the species, although a small proportion of aneuploid cells was observed (∼7%). At 37 °C there was a reduction in cell survival and no effects on cell viability at the H2O2 concentrations tested; however, there was a decrease in cell viability when exposed to aluminum in all the concentrations tested.. The growth behavior and karyotype observed indicate the establishment of a continuous cell culture with a stable genome that responds to environmental changes.

Revision of the punctatus species-group of Dissomphalus Ashmead (Hymenoptera, Bethylidae)

The Neotropical region is known for its high species diversity. Dissomphalus Ashmead exemplifies this phenomenon, being the most speciose genus within Bethylidae, with 34 species-groups and 287 species. Among these groups, punctatus is one of the smallest, comprising only seven species. The objective of this contribution is to conduct a taxonomic study of punctatus species-group in the Neotropical region. Our results are surprising by discovering forty-six species, thirty-nine of which are new to science: D. alexandrinae sp. nov., D. alzirae sp. nov., D. ameliae sp. nov., D. annae sp. nov., D. antonietae sp. nov., D. ashauerae sp. nov., D. beatrizae sp. nov., D. boriae sp. nov., D. carmenae sp. nov., D. carolinae sp. nov., D. dandarae sp. nov., D. deaneae sp. nov., D. elisae sp. nov., D. elzae sp. nov., D. enedinae sp. nov., D. eulaliae sp. nov., D. evaristoae sp. nov., D. grazielae sp. nov., D. guidonae sp. nov., D. jaquelineae sp. nov., D. johannae sp. nov., D. leliae sp. nov., D. limae sp. nov., D. lispectorae sp. nov., D. luisae sp. nov., D. lumae sp. nov., D. lutzae sp. nov., D. margarethae sp. nov., D. martae sp. nov., D. maryae sp. nov., D. meirelesae sp. nov., D. mirandae sp. nov., D. nisiae sp. nov., D. penhae sp. nov., D. ritae sp. nov., D. silveirae sp. nov., D. soniae sp. nov., D. sueliae sp. nov., D. vivianeae sp. nov. which are described and illustrated. The status of Dissomphalus montanus (Kieffer, 1910), stat. resurr. is resurrected from the synonymy of D. punctatus (Kieffer, 1910) seven are previously described: D. acutipupu Colombo & Azevedo, D. bahiensis Redighieri & Azevedo, D. cuca Colombo & Azevedo, D. montanus (Kieffer), D. napo Evans, D. punctatus (Kieffer) and D. tupinikim Colombo & Azevedo. A key to males of all species in this group is provided. Throughout this paper, we demonstrate the diversity found in the genitalia structures of this group and emphasize their importance in the taxonomy of Dissomphalus.

Trichomyia Haliday in Curtis (Diptera: Psychodidae) from southern Brazil: four new species and seven new records

The Neotropical region currently has the greatest richness of species in the genus Trichomyia Haliday in Curtis, but many regions, such as southern Brazil, have the fauna poorly explored. Here we describe four new species: Trichomyia brisolai sp. nov., T. aculeata sp. nov., T. marumbi sp. nov. and T. uncata sp. nov. and provide new records for seven brazilian species: T. inermis, T. brasiliensis, T. danieli, T. nocturna, T. riodocensis, T. truncata and T. mineira from the southern region of Brazil.

A new species of Gieysztoria Ruebush & Hayes, 1939 (Platyhelminthes, Rhabdocoela, Dalyelliidae) from Argentina with comments on geographical distribution of the genus in the Neotropical region

A new species of Gieysztoria Ruebush & Hayes, 1939 (Platyhelminthes, Rhabdocoela, Dalyelliidae) from Argentina with comments on geographical distribution of the genus in the Neotropical region

Identification and characterization of a novel Pavlovskyella (Acari: Argasidae) from Chile, parasite of the culpeo fox (Lycalopex culpaeus).

Soft ticks (Argasidae) of the subgenus Pavlovskyella Pospelova-Shtrom are worldwide distributed parasites of medical importance. However, the systematics of the subgenus are currently under debate because genetic data shows that the group is paraphyletic. Meanwhile, species of Pavlovskyella continue to be discovered. In this study a novel species of the subgenus is described from specimens collected on a fox in central Chile. The larva of this new species differentiates from other Pavlovskyella spp. by having the following combination of characters: subpyriform dorsal plate; 15 pairs of setae, 7 anterolateral, 3 central, and 5 posterolateral, and hypostome with denticles in the distal third. Nymphs and adults of the species lack cheeks, eyes or bulging structures on the flank, but exhibit dorsoventral grooves, and humps on tarsi I, II, and III. Moreover, a patch of glabrous integument appears on the distal portion of coxal folds. A phylogenetic analysis using the mitogenome indicates a monophyletic group composed by Ornithodoros (Pavlovskyella) brasiliensis Aragão, Ornithodoros (Pavlovskyella) furcosus Neumann, Ornithodoros (Pavlovskyella) improvisus Muñoz-Leal & Venzal, and Ornithodoros (Pavlovskyella) rostratus Aragão. Interestingly, a phylogeny using 18S-28S rDNA sequences shows that South American Pavlovskyella spp. are paraphyletic, as depicted in previous studies. Adding species of the subgenus from the Neotropical region to phylogenetic analyses could aid to solve this paraphyly. Furthermore, this is the fifth species of Pavlovskyella described in South America, and the second in Chile.

Pyriproxyfen exposure compromises cocoon spinning and damages the Malpighian tubules of the nontarget predator Ceraeochrysa claveri (Neuroptera: Chrysopidae)

Pyriproxyfen has been extensively employed in the Neotropical region for agricultural pest management and insect vectors. However, measuring the sublethal and indirect effects of this active ingredient on nontarget organisms, such as lacewings, is important. Using morphological tools on target organs, we can evaluate these effects and use them as biomarkers for future ecotoxicological studies. Here, we investigated the effects of pyriproxyfen exposure on cocoon spinning and Malpighian tubules in Ceraeochrysa claveri adults. For this purpose, first-instar C. claveri larvae were orally exposed to Diatraea saccharalis egg clusters treated with pyriproxyfen in a solution of 50 or 100 mg a.i. L-1 throughout the larval stage. Insecticide exposure decreases predator survival, mainly in the prepupal and pupal stages, along with changes in the internal and external surfaces and thickness of the cocoon wall. Histopathological and ultrastructural injuries, including cytoplasmic vacuolization, loss of microvilli and a reduction in neutral glycoconjugates, were observed in Malphigian tubule cells of adults (≤ 24 h old). These changes indicate toxicological effects on Malpighian tubules that in lacewing involve cocoon spinning during metamorphosis and, in the adult stage, act in physiological processes of excretion and osmoregulation. Furthermore, it can affect the efficiency of the cocoon in protecting the specimen during metamorphosis against natural enemies and environmental factors. This organ has demonstrated its applicability as a biomarker for assessing the multisystemic effects of insecticides, thereby assisting in future risk assessments aimed at conserving nontargeted specimens.

Systematics of Apatelodidae Neumoegen & Dyar, 1894 (Lepidoptera: Bombycoidea) based on molecular and morphological data.

Apatelodidae is a family of New World bombycoids distributed mainly in the Neotropical region, with 14 genera, 222 valid species and 8 subspecies. These moths are medium-sized with a wingspan ranging from 2 to 8cm, generally greyish, straw-yellow or reddish-brown, with darker spots and lines on the dorsal side of the wings. We combine adult morphology and molecular data to test, under a probabilistic framework, the monophyly of apatelodid genera and the placement of Tamphana (Bombycidae). We sampled the type species of 12 of the 14 valid genera of Apatelodidae, including the type species of synonymised genera. We sampled ~75% of the species from all valid genera in the family and outgroups from Bombycidae, Brahmaeidae, Eupterotidae and Phiditiidae, totalling 195 terminals. Examination of the specimens resulted in a matrix of 138 morphological characters (116 from male; 22 from female) from the head (7 from male; 1 from female), thorax (37 from male; 4 from female), abdomen (5 from male) and genitalia (66 from male; 17 from female). For the molecular analyses, we used four genes: DDC (647bp) for 14% of terminals; CAD (2486bp) for 23% of terminals, Wgl (409bp) for 38% of terminals and COI (658bp) for 75% of terminals. Species of Tamphana were recovered in Apatelodidae as two independent clades. The genera Arotros , Crastolliana , Drepatelodes , Pantelodes , and Prothysana were recovered as monophyletic. The remaining apatelodid genera were polyphyletic. We propose a new genus-level classification: Tamphana is transferred to Apatelodidae; 16 new genera are proposed: Aymara gen. nov. , Campesina gen. nov. , Caribas gen. nov. , Cecile gen. nov. , Kaweskar gen. nov. , Lempira gen. nov. , Misak gen. nov. , Mocambo gen. nov. , Nhanderu gen. nov. , Peabiru gen. nov. , Raoni gen. nov. , Tapuia gen. nov. , Tibira gen. nov. , Tupac gen. nov. , Tuyvae gen. nov. and Zapata gen. nov. Two new species are described: Mocambo lauracensis sp. nov. , and Nhanderu takua sp. nov. We revalidate the genus Hygrochroa stat. rev. and three species: Carnotena perlineata stat. rev., Tupac bombycina stat. rev., comb. nov. and Zanola vivax stat. rev. Overall, we propose 82 new generic combinations, synonymise 16 species, and restore the status of 3 species: Apatelodes floramia stat. rest. , Carnotena rectilinea comb. nov. , stat. rest. and Ephoria nubilosa stat. rest. Additionally, we summarise data on the natural history and distribution of each Apatelodidae species. ZooBank: urn:lsid:zoobank.org:pub:254AA924-30B3-48A8-AB15-CCF2745C3B8E.

Two centuries of ornithological exploration of the Rio Doce Basin, southeastern Brazil. Part II—A catalogue of its birds and a gazetteer

The Rio Doce Hydrographic Basin (RDB) lies almost completely in the Brazilian Atlantic Forest, a highly threatened tropical rainforest. The RDB has suffered dramatic anthropogenic impacts during the last two centuries and is currently one of the most degraded regions in southeastern Brazil. In this paper, we gathered 140,742 bird records collected since the early 19th by more than two thousand naturalists, professional scientists, and citizen scientists. This vast database was compiled from several sources, including published literature, unpublished technical reports, natural history museums, and citizen science platforms. After checking and standardizing the database, we found high species richness in the RDB, with 689 species recorded to date, from which 675 (98%) were documented by specimens or digital vouchers. This database is presented as a detailed catalogue, including maps containing all localities in which each species has been recorded. We present text accounts for 40 noteworthy species recorded in the RDB, and a complete gazetteer for the 636 localities sampled. Preliminary analyses reveal that the RDB avifauna suffered a dramatic change in its species composition during the last two centuries, mostly due to human activity. Highly sensitive species associated to pristine forests vanished, while species associated to dry and open habitat expanded their ranges in the RDB. Finally, in addition to thoroughly characterization of the RDB avifauna, this paper provides the basis for a series of studies about the avifauna of one of the hottest hotspots of biodiversity in the entire Neotropical region.

Black flies (Diptera: Simuliidae) in the Galapagos Islands: Native or adventive?

Invasive species are a threat to ecosystems worldwide, but determining if a species is adventive or native is not always straightforward. The black flies that inhabit the Galapagos Islands, long known as Simulium ochraceum, are blood-feeding pests of humans and livestock. They first came to the attention of residents in 1989, suggesting a recent arrival. Earlier colonization, however, has been suggested, based largely on polymorphic genetic loci. To address questions of origin, provenance, and length of residency, we conducted a macrogenomic analysis of the polytene chromosomes of the S. ochraceum complex from seven sites in the Galapagos Islands and 30 sites in mainland Ecuador, Central America, and the Caribbean. Among 500 analyzed larvae, we discovered 88 chromosomal rearrangements representing 13 cytoforms, at least seven of which are probably full species. All evidence points to a single, cohesive cytoform with full species status in the Galapagos, conspecific with mainland populations, and widely distributed in the Neotropical Region. It has an identical, nearly monomorphic banding sequence with 10 novel fixed inversions and a subtle but unique Y-linked chromosomal rearrangement across all populations sampled in the Galapagos, the mainland, and the Caribbean. We recalled the name Simulium antillarum from synonymy with S. ochraceum and applied it to the Galapagos black flies, and we established that wolcotti is a junior synonym of antillarum. The time(s) and mode(s) of arrival of S. antillarum in the Galapagos remain uncertain, although the wide geographic distribution, including islands in the Caribbean, suggests that the species is an adept colonizer. Regardless of how long it has been in the archipelago, S. antillarum might have assumed a functional role in the streams of San Cristobal, but otherwise has had a detrimental effect on humans and livestock and potentially on the unique birds and mammals of the Galapagos Islands.

A specimen-based database of small-eared shrews (Mammalia, Eulipotyphla, Cryptotis) in the Neotropical Region.

This database compiles comprehensive occurrence information, based on voucher specimens of small-eared shrews, genus Cryptotis, that occur from México to Peru. The database integrates the information obtained from four main sources: natural history museums, public databases, fieldwork and scientific literature. It contains 3,639 records from 53 species in 12 countries. Of the total, 83.54% have collecting dates, 51.36% of the specimens are sexed and 84.56% have decimal degrees coordinates. By generating this database and making it publicly available, we hope to improve the biological knowledge of this group of small mammals still poorly studied in the region. It aims to be a valuable resource for students, researchers, conservationists and decision-makers. The dataset contains information on all species of the genus Cryptotis in the Neotropical Region (namely from México to Peru), incorporating the most updated taxonomic and nomenclatural changes. The database includes records in regions and countries that are poorly represented in currently available data repositories. Most records have verified temporal and spatial information.

Morphological data and DNA barcoding reveal the presence of the alien freshwater leech Helobdella octatestisaca (Hirudinida: Glossiphoniformes) in North Africa (Tunisia).

We hereby report the first occurrence of Helobdella octatestisaca in North Africa, specifically in Tunisia, as a likely introduced species from the Neotropical Region. Historically, leeches bearing a prominent chitinous scute on their dorsal surface were commonly diagnosed as H. stagnalis. Most probably, H. octatestisaca had previously been misidentified as H. stagnalis in Tunisia. The identification was primarily based on morphological evidence, supplemented by genetic data obtained from COI DNA barcoding. The morphology of the examined specimens was consistent with the original species description, notably characterized by the presence of four pairs of testisacs. To support our findings, we conducted a phylogenetic analysis using the Maximum Likelihood method based on COI alignment constructed with the newly obtained sequence from Tunisian specimens and complete or nearly complete 'Folmer fragment' sequences of congeners sourced from the GenBank database. This study highlights the first identification of H. octatestisaca in North Africa and suggests that previous records of H. stagnalis in Tunisia likely misidentified this species.

Differential climatic niche diversification processes in South American rodents (Octodontoidea) across tropical and extratropical regions

ABSTRACT Studying niche evolution becomes central to understanding the processes driving species diversification along latitudinal gradients. Octodontoidea rodents serve as a model group for understanding how the colonisation of extratropical regions has shaped the climatic niche evolution of species. We analyse the time and mode of climatic niche evolution among different Octodontoidea lineages to understand how niche evolutionary processes operate across the spatial gradient of the Neotropical region. We constructed ecological niche models for living Octodontoidea species to assess the timing and mode of climatic niche evolution across tropical and extratropical lineages. We estimated niche similarity and correlated it with species divergence times, and estimated the rate of climatic niche diversification across lineages. Our results show a trend of greater niche overlap in more recent lineages and lower niche overlap in older lineages. However, extratropical lineages exhibit lower climatic niche overlaps. From diversification analysis, we detected that the Ctenomyidae group shows higher rates of niche diversification, whereas the tropical Echimyidae group exhibits the lowest rates of climatic niche diversification. Our results support the idea that the lineages restricted to tropical regions tend towards niche conservatism. However, some tropical lineages have successfully colonised extratropical regions, and this colonisation has been accompanied by strong selective pressures, leading to higher rates of niche diversification and lower climatic niche overlap among species.

Bird Leg Skin Lesions and Urbanization in a Neotropical Savanna City.

Urban sprawl threatens biodiversity and is responsible for significant changes in the species that live in these environments. Given the high cost of comprehensive surveillance, monitoring disease indirectly, such as detecting skin lesions in birds, may help us better understand the prevalence of diseases affecting wild populations. We assessed the frequency of leg skin lesions, as a proxy of disease presence, in 1,565 individuals of 25 species, along the urban matrix of a large Neotropical city, Brasília, Federal District, Brazil. We tested the hypothesis that there is an increase in the frequency of skin lesions in birds due to urban intensification. We observed an increasing trend in some bird species between the frequency of occurrence of lesions and the intensity of urbanization. Species with a higher number of captures had an increase in the percentage of lesions, indicating that the occurrence of lesions may be linked to higher population density or that detection of the effect occurs only when sample sizes are high and controlled among urbanization categories. Our study highlights how the intensity of urbanization may increase the risk of disease transmission for these species. Unfortunately, studies on this topic are scarce in Neotropical regions, despite the region's high biodiversity and urban expansion.

Assessing Hydrological Response and Resilience of Watersheds as Strategy for Climatic Change Adaptation in Neotropical Region

This study aimed to assess the hydrological response and resilience of watersheds in a neotropical region to identify regions sensitive to climate variations, enabling the development of adaptive strategies in response to global environmental changes. This study applied Budyko’s framework using Fuh’s hydrological model rewritten by Zhou to estimate hydrological response and Budyko’s metrics (deviation and elasticity) to estimate hydrological resilience to climatic changes in 26 watersheds in southeastern Brazil. The proposed modeling was able to capture the differences among the watersheds, with “m” values ranging from 1.79 to 3.63. It was possible to rank the hydrological resilience from low to high across watersheds using Budyko’s metrics, where the highest values of elasticity were found in watersheds with a higher percentage of forest cover. The sensitive analyses showed that watersheds with higher “m” values are more sensitive to changes in precipitation and potential evapotranspiration. The results also demonstrate that mean elevation and stream density were two key variables that influence the “m” value; these physiographic characteristics may alter the water and energy balance of the watershed affecting the water yield. A relationship between watershed’s hydrological response and resilience was proposed to identify critical areas for the stability of water yield in the watersheds, providing a guide for public policy and suggesting ways to help the management of water resources in watersheds.

Exploring Natural Infection in Alternative Hosts of Corn Stunt Spiroplasma and Tracking the Temporal Dynamics of Corn Stunt Disease in the Brazilian Cerrado Biome

The corn stunt disease complex, caused by the mollicutes Spiroplasma kunkelii (Css) and the maize bushy stunt (MBS) phytoplasma, is a major phytosanitary issue for corn production in the neotropical region of Brazil. In this study, we investigated the presence of alternative hosts for S. kunkelii (Css) in the Brazilian Cerrado biome and explored the potential for asymptomatic Css infections in maize plants. To identify possible alternative hosts, we collected samples from ornamental and native plants located in Cerrado regions with a high incidence of corn stunt disease. We also monitored the disease’s progression over time and calculated the area under the disease progression curve (AUDPC). Additionally, we sampled healthy, asymptomatic maize plants growing near symptomatic ones and analyzed all the samples using qPCR to detect the pathogen. Our results showed no Css infection in the sampled alternative host species and no asymptomatic infections in the nearby maize plants. The incidence of maize stunting varied significantly among the sample years and counties. In Aparecida do Rio Negro, the infection rate was six times higher in 2020 compared to 2019, while Porto Nacional showed an 11-fold increase. During surveillance from March to July, the infection rate at the Sierra site went from less than 3% in March 2019 to 6% in July (F1,4 = 415.84; p = 0.0003). MBS infection increased significantly, while S. kunkelii remained stable below 3%. In 2020, MBS increased from 3% to more than 12%. A similar trend was observed at the Sede site, where MBS increased from 9% in 2019 to 11% in 2020. An increase in the AUDPC was observed both within individual years and between 2019 and 2020, indicating a worsening trend in disease severity. Overall, our findings reinforce the need for preventive measures in managing maize crop fields.

Pathways for accidental biocontrol: The human-mediated dispersal of insect predators and parasitoids.

Introductions of insect predators and parasitoids for biological control are a key method for pest management. Yet in recent decades, biological control has become more strictly regulated and less frequent. Conversely, the rate of unintentional insect introductions through human activities is rising. While accidental introductions of insect natural enemies can potentially have serious ecological consequences, they are challenging to quantify as their movements go largely unobserved. We used historical border interception records collected by the US Department of Agriculture from 1913 to 2018 to describe the diversity of entomophagous insects transported unintentionally, their main introduction pathways, and trends in host specificity. There were 35,312 interceptions of insect predators and parasitoids during this period, representing 93 families from 11 orders, and 196 species from these families. Commodity associations varied, but imported plants and plant products were the main introduction pathway. Most interceptions originated with commodities imported from the Neotropical, Panamaian, and Western Palearctic regions. Among the intercepted species, 27% were found in material originating from more than one country. Two thirds of species were polyphagous host generalists. Furthermore, 25% of species had already been introduced intentionally as biological control agents internationally, and 4.6% have documented negative impacts on native biodiversity or human society. Most of the intercepted species that have not established in the United States are host generalists or have at least one known host species available. The unintentional transport of diverse natural enemy insects has the potential to cause substantial ecological impacts, both in terms of controlling pests through accidental biocontrol and disrupting native communities. Characterizing the insects being transported and their introduction pathways can inform biosecurity practices and management.