Sergio R. Sánchez-Peña

Occurrence of Entomopathogenic Fungi from Agricultural and Natural Ecosystems in Saltillo, México, and their Virulence Towards Thrips and Whiteflies

Abstract Entomopathogenic fungi were collected from soil in four adjacent habitats (oak forest, agricultural soil, pine reforestation and chaparral habitat) in Saltillo, México using the insect bait method with Tenebrio molitor (L.) (Coleoptera: Tenebrionidae) larvae as bait. Overall, of the larvae exposed to soil, 171 (20%) hosted Beauveria bassiana (Balsamo) Vuillemin (Hypocreales: Cordycipitaceae), 25 (3%) hosted Metarhizium anisopliae (Metschnikoff) Sorokin (Hypocreales: Clavicipitaceae) and 1 (0.1%) hosted lsaria (=Paecilomyces) sp. (Hypocreales: Cordycipitaceae). B. bassiana was significantly more frequent on larvae exposed to oak forest soil. M. anisopliae was significantly more frequent on larvae exposed to agricultural soil. From the infected bait insects, 93 isolates of B. bassiana and 24 isolates of M. anisopliae were obtained. Strains were tested for their infectivity against Cuban laurel thrips, Gynaikothrips uzeli Zimmerman (Thysanoptera: Phlaeothripidae) and the greenhouse whitefly, Trialeurodes vaporariorum (Westwood) (Hemiptera: Aleyrodidae). B. bassiana isolates caused the highest mortality on thrips (some causing 88% mortality after 6 days); both fungal species caused similarly high mortality levels against whiteflies (75%) after 6 days. Large amounts of germplasm of entomopathogenic fungi, fundamentally B. bassiana and M. anisopliae, exist in the habitats sampled; pathogenicity varied among strains, and some strains possessed significant virulence. Soils in these habitats are reservoirs of diverse strains with potential for use in biocontrol.

Pathogenicity of Hirsutella citriformis (Ascomycota: Cordycipitaceae) to Diaphorina citri (Hemiptera: Psyllidae) and Bactericera cockerelli (Hemiptera: Triozidae)

BioOne sees sustainable scholarly publishing as an inherently collaborative enterprise connecting authors, nonprofit publishers, academic institutions, research libraries, and research funders in the common goal of maximizing access to critical research. Pathogenicity of Hirsutella citriformis (Ascomycota: Cordycipitaceae) to Diaphorina citri (Hemiptera: Psyllidae) and Bactericera cockerelli (Hemiptera: Triozidae)

Activity of oil-formulated conidia of the fungal entomopathogens Nomuraea rileyi and Isaria tenuipes against lepidopterous larvae

The fungi Nomuraea rileyi and Isaria tenuipes (=Paecilomyces tenuipes) are ecologically obligate, widespread pathogens of lepidopterans. Bioassays were carried out to evaluate the activity of oil-suspended conidia of N. rileyi and I. tenuipes against larvae of Spodoptera frugiperda, Spodoptera exigua, Helicoverpa zea, and Heliothis virescens. The tests consisted of two bioassay sets. In the first set, conidia of N. rileyi and I. tenuipes were suspended in water+Tween 80, and in vegetable (canola, soybean) and mineral (proprietary mixture of alkanes and cyclic paraffins) oils, and tested against S. frugiperda. Both fungi were highly compatible with oils and caused mortalities near 100% in all oil treatments; the lowest LT(50) values were 4.7 days for N. rileyi in mineral oil and 6.0 days for I. tenuipes in soybean oil. The second set included additional fungal strains and oil formulations (mineral, canola, sunflower, olive and peanut oils) tested against larvae of S. exigua, S. frugiperda, H. zea and H. virescens. The highest activity was that of N. rileyi in mineral oil against Spodoptera spp., with LT(50) values of 2.5 days (strain ARSEF 135) and 3 days (strain ARSEF 762) respectively. For two different isolates of I. tenuipes the lowest LT(50) values (5.1-5.6 days respectively) were obtained with mineral oil formulations against Spodoptera spp. and H. zea respectively. Additionally, we tested both fungi against prepupae of all four lepidopteran species. Mortalities with I. tenuipes against S. exigua ranged from 90% to 100% (strains ARSEF 2488 and 4096); N. rileyi caused 95% mortality on S. frugiperda. The activity of formulations depended on host species and oil used; Spodoptera spp. was more susceptible to these fungi than Heliothis and Helicoverpa. The results indicate that a comprehensive evaluation of these entomopathogens in agriculture using oil application technologies is advisable, particularly, in organic and sustainable settings.

Molecular diversity of the microsporidium Kneallhazia solenopsae reveals an expanded host range among fire ants in North America.

Kneallhazia solenopsae is a pathogenic microsporidium that infects the fire ants Solenopsis invicta and Solenopsis richteri in South America and the USA. In this study, we analyzed the prevalence and molecular diversity of K. solenopsae in fire ants from North and South America. We report the first empirical evidence of K. solenopsae infections in the tropical fire ant, Solenopsis geminata, and S. geminata×Solenopsis xyloni hybrids, revealing an expanded host range for this microsporidium. We also analyzed the molecular diversity at the 16S ribosomal RNA gene in K. solenopsae from the ant hosts S.invicta, S. richteri, S. geminata and S. geminata×S. xyloni hybrids from North America, Argentina and Brazil. We found 22 16S haplotypes. One of these haplotypes (WD_1) appears to be widely distributed, and is found in S. invicta from the USA and S. geminata from southern Mexico. Phylogenetic analyses of 16S sequences revealed that K. solenopsae haplotypes fall into one of two major clades that are differentiated by 2-3%. In some cases, multiple K. solenopsae haplotypes per colony were found, suggesting either an incomplete homogenization among gene copies within the 16S gene cluster or multiple K. solenopsae variants simultaneously infecting host colonies.

Some Fungus-Growing Ants (Hymenoptera: Formicidae) from Northeastern Mexico

ABSTRACT The fungus-growing ants (Hymenoptera: Formicidae: Attini) of northeastern Mexico are poorly known. Herein new distributional records in NE Mexico and habitat observations are provided for the fungus-growing ants Apterostigma mexicanum Lattke, Atta texana (Buckley), Cyphomyrmex rimosus (Spinola), Mycocepurus smithii Forel, Mycetosoritis hartmanni Wheeler, Sericomyrmex aztecus Wheeler, Trachymyrmex smithi Buren, and Trachymyrmex turrifex Wheeler.

New View on Origin of Attine Ant-Fungus Mutualism: Exploitation of a Preexisting Insect-Fungus Symbiosis (Hymenoptera: Formicidae)

Abstract Current hypotheses on the origin of the fungus–attine ant (Hymenoptera: Formicidae) symbiosis propose, as an ancestral first step in the development of fungal cultivation, fortuitous feeding on fungi growing adventitiously on substrates such as rotting wood, insect parts, seeds stored by ants in nests, regurgitated infrabuccal pellets, free-living soil fungi, or mycorrhizae. However, feeding-deterrent fungi regularly colonize these substrates. De novo feeding on these fungi by the attine ancestor is unlikely because the almost universal presence of mycotoxins on adventitious fungi is a formidable barrier to mycophagy. In addition, there is no evolutionary history of mycophagy in the Hymenoptera. Instead, I propose that attine mycophagy began from opportunistic, selective feeding on wood-colonizing fungi previously “domesticated” by other insects: ambrosia beetles: (Coleoptera: Curculionidae: Scolytinae or Platypodinae); and less likely, woodwasps (Hymenoptera: Siricoidea). Attine ancestors foraged for beetle brood and fungal biomass in the galleries of those insects, which provided the attine ancestor with fungi that were nutritious and nontoxic to insects. The invading ants’ debris (fecal spots, exuviae, meconia, and saliva) possibly allowed the growth of the “good” domesticated fungi in galleries, while ants mechanically eliminated undesirable ones. Feeding on beetle fungi first allowed the development of broad mycophagy in ants, and, later, of the gardening habits. Subsequently, more restricted, specific mycophagy evolved. Only after serious barriers were overcome did incipient mycophagy develop, followed by cultivation. The ambrosia fungi-lined beetle galleries in wood provide one location favorable for this sequence. An analogous progression in mycophagy and incipient fungus manipulation, departing from the omnivore diet has occurred in Megalomyrmex ants that feed parasitically on brood and/or fungus gardens of attines. Colonies of the ancestral attine nested in wood and adopted mated foundress queens after mating flights, and colonies reproduced by budding. Queen adoption by established colonies allowed the chronological continuation of the incipient symbiosis. Mycophagy preadapted the ants to test free-living fungi in wood and soil as cultivars. The fortuitous finding of more adequate lepiotaceous strains in soil allowed the adaptive radiation exhibited in present-day attines. The cultivation, by the primitive attine Apterostigma, of wood-colonizing Basidiomycotina is possibly of ancestral significance.

Geographical Distribution of Bagrada hilaris (Hemiptera: Pentatomidae) in Mexico

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae), commonly known as Bagrada bug or painted bug, is a major pest of commercial cruciferous plants. It is an Old World insect native to Africa, Asia, and southern Europe (Taylor et al. 2015, Ann. Entomol. Soc. Am. 108: 536–551). Bagrada hilaris was first discovered in the United States in 2008 in Los Angeles, CA (Huang et al. 2014, Crop Prot. 59: 7–13). Since then, it has rapidly expanded its range into Arizona, Nevada, New Mexico, and west Texas (Reed et al. 2013, Int. J. Pest Manag. 4: 1–7). Bagrada hilaris feeds on apical meristems, cotyledons, and leaves of cruciferous hosts, causing economic losses (Palumbo 2014, Veg. West 18: 18–20). Seedling mortality reportedly reached 60% in some fields in California in 2009 (Reed et al. 2013). Bagrada hilaris was first reported in Mexico at Saltillo, state of Coahuila (Sánchez-Peña 2014, Southwest. Entomol. 39: 375–377). Severe crop damage has already been observed in Sonora state. In Saltillo, it has been observed feeding on broccoli (Brassica oleracea var. italica L.), radish (Raphanus sativus L.), London rocket (Sisymbrium irio L.), and wild arugula (Eruca sativa [L.] Miller). The potential impact of this pest in cruciferous crop production is considerable for Mexico, with 40,000 ha in cole crop production in 2014 (Servicio de Información Agroalimentaria y Pesquera [SIAP], 2014. Accessed 20 Sep 2015. www.siap.gob.mx.). Several generations can develop per year; specific natural enemies were absent in Saltillo (R.I.T.A. and S.R.S.P. unpubl. obs.). In 2014, the main states producing broccoli were in central Mexico: Guanajuato (292,345 t), Michoacán (45,878 t), and Puebla (26,002 t). The main states producing radish were Puebla (13,271 t), Sonora (5,964 t), and Baja California (5,598 t) (SIAP 2014). Herein, we report information on the geographical distribution of the Bagrada bug in Mexico as a baseline for future biological and management studies of this pest.

Field Trial of Aqueous and Emulsion Preparations of Entomopathogenic Fungi Against the Asian Citrus Psyllid (Hemiptera: Liviidae) in a Lime Orchard in Mexico

Liberibacter-caused Huanglongbing disease vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), has spread to most citrus-growing areas worldwide. In Mexico, research efforts to manage the disease and to slow its spread have intensified since it was detected there in 2009. Integration of microbial control with other management practices should be investigated for D. citri and the disease (Meyer et al. 2008, J. Invertebr. Pathol. 99: 96–102). To that end, we assessed the impact of applications of entomopathogenic fungi on D. citri nymphs in a single test conducted in a commercial Persian lime (Citrus latifolia Tanaka) orchard in Veracruz, Mexico, in 2011. Three fungi were evaluated. Beauveria and Metarhizium isolates were isolated from soil with the insect-bait method using Tenebrio molitor L. larvae (Sanchez-Pena et al. 2011, J. Insect Sci. [BioOne Paper No. 1, 10 pg.]) in the citrus-growing region in Nuevo Leon, Mexico. Isaria fumosoroseaWize was isolated from D. citri collected in Gomez Farias, Tamaulipas (Casique-Valdez and Sanchez-Pena 2010, 58th Annual Meeting Southwestern Branch, Entomological Society of America, Cancun, Mexico). One isolate each of Beauveria sp. (B6C), I. fumosorosea (IF8B19), andMetarhizium sp. (M11) were selected for field tests based on (a) activity against D. citri nymphs in the laboratory and (b) stable and uniform production of conidia on autoclaved rice grains (Casique-Valdez 2010, MS Thesis, Universidad Autonoma Agraria Antonio

Identification of Fire Ants (Hymenoptera: Formicidae) from Northeastern Mexico with Morphology and Molecular Markers

ABSTRACT The invasive red imported fire ant, Solenopsis invicta Buren, has successfully dispersed across many countries from its South American homeland and now has reached the US-Mexico border (e.g., Matamoros, state of Tamaulipas, México), where it now coexists with native fire ants, Solenopsis geminata, Solenopsis xyloni, and others. The morphological identification of Solenopsis spp. workers is difficult, particularly small ones. We examined the sequence of the cytochrome oxidase I (COI) mitochondrial gene (mtDNA) as a marker for fire ants collected at several Mexican localities. PCR products from this locus yielded unique sequences and restriction patterns that allowed distinguishing between S. invicta, S. geminata, and specimens harboring S. xyloni sequences. The S. invicta sequences obtained were 99% identical to sequences reported from Florida and New Mexico specimens. The S. xyloni sequences obtained were 96% identical to New Mexico sequences. The S. geminata sequences were similar (93% identity) to those from Florida, and shared a Hinf I restriction site with some but not all Florida sequences. The S. xyloni sequences were detected in S. geminata/S. xyloni hybrids identified by morphology; along with other characters, the marker allows their characterization.

Note:In vitro antagonism of actinomycetes isolated from fungus-growing ants against plant pathogenic fungi

Fungus-growing ants have been found recently to be symbiotic with actinomycetes living on the ant’s cuticle; these bacteria are inhibitory to soil fungi that are detrimental to the ants’ fungus gardens. In order to investigate whether actinomycetes found on the cuticle of attine ants also had inhibitory properties against plant pathogenic fungi, we isolated 32 strains of actinomycetes from fungus-growing ants (Atta, Trachymyrmex, andCyphomyrmex), from the Mexican states of Coahuila, Nuevo León and Tamaulipas. Of the actinomycetes tested against selected plant pathogenic fungi (Alternaria solani, Aspergillus flavus, Colletotrichum lindemuthianum, Rhizoctonia solani, Sclerotium sp.) on Czapek-Dox agar medium, 13 isolates inhibited at least one of the fungi.C. lindemuthianum was inhibited by 11 actinomycetes, andRhizoctonia by three. An actinomycete strain isolated fromCyphomyrmex rimosus inhibited all five fungi tested.