Sergio René Sánchez Peña

Aim: We develop Atta leafcutter-ants as bioindicators that respond at fine scales to geographic and seasonal climate changes in the Americas, thereby addressing the paucity of versatile insect bioindicator systems capable of monitoring climate in both Southern and Northern Hemispheres. Location: American tropics and sub-tropics from latitudes S33.6 to N33.2, with case studies from Colombia, Mexico, and southern USA. Time Period: 2012-2024. Taxon Studied: Atta leafcutter-ants. Methods: We elucidate biogeographic patterns of mating-flight phenology of Atta leafcutter-ants across the entire Atta range from Uruguay/Argentina to the USA, using 2335 records of Atta reproductives from the community database iNaturalist, then ground-truth these patterns by comparison with (i) mating-flight records (n=806) from the Atta literature; and (ii) mating-flight observations (n=836) accumulated by a consortium of experts who have researched Atta for a combined 1000+ work-years. Onset of mating flights can be timed with great precision in Atta populations because mass-mating flights are synchronized and triggered by the first major rainfall of a rainy season. Results: Biogeographic patterns in climate-dependent mating-flight phenologies recorded at iNaturalist are corroborated by observations accumulated in the literature and by Atta experts. Analyses reveal so-far unknown gradients in mating-flight phenology (e.g., Colombia to USA) that are correlated to geographic climate gradients, and season switches of mating flights from early to late in the year between proximate Atta populations (e.g., 200 kilometers apart), for example in the climatically complex Andean regions of Colombia. Regional differences in Atta mating-flight phenology correspond to temporal differences in rainfall between ecoregions of Colombia. Main Conclusions: Atta ants are tractable insect bioindicators to monitor climate impacts with detailed spatial and temporal resolution across a 9200-kilometer trans-equatorial transect in the Americas. We outline future research directions to explore climate-dependent biology using the continuously growing, and now ground-truthed, information at iNaturalist on Atta mating behavior.

Candidatus Liberibacter solanacearum (CLso) transmission by Bactericera cockerelli (Šulc) (Hemiptera: Triozidae) impacts solanaceous crops. CLso was detected in Berlandier’s wolfberry ( Lycium berlandieri Dunal; Solanaceae) leaf and branch tissues, and in B . cockerelli adults (43.75 %, n = 80) developing from this plant in the field in northeastern Mexico, confirming CLso acquisition by B . cockerelli from wolfberry. Symptoms and molecular detection indicated that B . cockerelli transmits CLso from wolfberry to chili pepper ( Capsicum annuum L.; Solanaceae). Lycium berlandieri is a wild reservoir of B . cockerelli and CLso. Results are consistent with greenhouse trials and represent the first confirmation of B . cockerelli full development on L. berlandieri in the field.

The subphylum Entomophthoromycotina (Phylum Zoopagomycota) includes many arthropod pathogens, some of which are renowned for their abilities to alter host behavior prior to death and cause epizootics that impact host populations. The last checklist of arthropod-pathogenic species in this group was published in 1963 and consisted of 39 species in a single genus. Since then, more species have been named, and their taxonomy has changed extensively. We have constructed an updated checklist for species of Entomophthoromycotina in North America; this checklist includes species in the continental United States, Canada, and Mexico. Data were compiled based on available published literature and metadata available from the ARSEF culture collection, adjusting names based on current taxonomy. In North America, the arthropod-pathogenic Entomophthoromycotina now include 80 species belonging to 14 genera, within two classes, plus one species in a form genus. This checklist provides a current framework for future studies of the biodiversity of this group of fungi.

Invasive species are a leading cause of global biodiversity decline. Larvae of the cactus moth Cactoblastis cactorum Berg (Lepidoptera: Pyralidae: Phycitinae) consume prickly pear cactus species ( Opuntia ; Cactaceae) in its native South American range. High host specificity made C. cactorum an appropriate biological control agent of Opuntia species, which have become invasive weeds around the world. This biological control program was successful. Ironically, the success of cactus weed biological control facilitated a series of events which led to C. cactorum invasion of North America where Opuntia diversity is tremendous. In 2017, C. cactorum established along the southeast Texas coast. In 2020, we began monitoring C. cactorum dispersal towards south and south-west Texas with cactus moth pheromone traps. Our objectives were to document the extent of the invasion and calculate dispersal rates towards commercial Opuntia -growing regions in Mexico. There are four overlapping moth flight peaks in Texas. Between 2017 and 2022, the C. cactorum populations invaded over 27,000 km ² in south-east and south-central Texas at a dispersal rate up to 47 km year. Since 2022, this dispersal rate slowed as the moth invasion front came into contact with the Tamaulipan thornscrub region of south Texas where Opuntia density is high and native cactus moth species are attacked by a diverse assemblage of parasitoids. We present data on the density of native cactus moth species in Texas which shows that their density increases west and south-west of the area currently occupied by C. cactorum . These data suggest that apparent competition may be occuring between C. cactorum and native cactus moth species via shared parasitoids. This hypothesis is not mutually exclusive of other biological barriers that may contribute to explaining why the Texas C. cactorum dispersal rate has slowed significantly. We conclude with a discussion about how to leverage these data to support future deployment of C. cactorum biological control agents in Texas.

A collection of egg parasitoids in the Scelionidae are identified as members of the Telenomus californicus Ashmead, 1893 complex (californicus+dalmanni+arzamae groups). They were reared from eggs of the cactus zebra worm, Melitara cf. junctoliniella Hulst, 1900 (Pyralidae: Phycitinae) infesting Opuntia streptacantha Lemaire, 1839 (Cactaceae) at Bustamante, Nuevo León, Mexico. Lacking both male specimens and a revision of the complex, no species-level identification could be made. The taxonomic placement of these wasps is discussed as well as possible implementation of these egg parasitoids in new-association biological control of the invasive cactus moth Cactoblastis cactorum (Berg, 1885) (Pyralidae: Phycitinae) in North America.

Diaphorina citri Kuwayama (Hemiptera: Liviidae) is a vector of Liberibacter asiaticus Jagoueix et al. and Liberibacter americanus Teixeira et al., causal agents of the critical yellow dragon disease or Huanglongbing (HLB), which affects citrus production worldwide. Recently, green synthetic nanoparticles have emerged as a potential alternative to control of agricultural insect pests. The insecticide effect of silver nanoparticles (AgNPs) on 2nd instar nymphs of D. citri under laboratory and greenhouse conditions was evaluated. Mortality was recorded 24, 48, and 72 h after application on D. citri nymphs under both laboratory and greenhouse conditions. The laboratory results showed that AgNPs caused 97.84 and 100% mortality at 32 and 64 ppm, respectively, 72 h after treatment. In the greenhouse, AgNPs caused 78.69 and 80.14% mortality using 64 and 128 ppm 72 h after application. This research is the first to evaluate the green synthesis AgNPs on D. citri and are a promising strategy to control the pest.

Novel trophic associations have sometimes resulted in fortuitous and significant biological control. After the invasion of North America by the South American cactus moth, Cactoblastis cactorum (Berg) (Pyralidae: Phycitinae), it is pertinent to characterize the assemblage of local natural enemies that could utilize this moth in new host-parasitoid associations. Herein we report on Apanteles mimoristae Muesebeck (Braconidae: Microgastrinae), a North American gregarious endoparasitoid wasp attacking the caterpillar of the phycitine cactus moth Melitara cf. nephelepasa (Dyar) (Pyralidae: Phycitinae, also known as zebra worm), also native to North America; both collected in Opuntia ficus-indica (L.) Mill. (Cactaceae) cultivated fields at rural areas of Mexico City. We provide an updated morphological account for A. mimoristae visualized with light microscopy and scanning electron microscope (SEM); a fragment of its cytochrome oxidase subunit I (COI) gene sequence data is reported for the first time. Additionally, we analyze its taxonomical position relative to other Apanteles species from the Americas including those attacking cactus-feeding moths. Our analyses place A. mimoristae (from Mexico) in a clade with A. esthercentenoae Fernández-Triana (from Costa Rica), a parasitoid of both Cromarcha stroudagnesia Solis (Pyralidae) and Palpita venatalis (Schaus) (Crambidae) (non cactus-feeding), and in a sister clade to A. opuntiarum Martínez & Berta (from Argentina) and A. alexanderi Brèthes (from Argentina and Uruguay), parasitoids of the cactus-feeding phycitines Cactoblastis and Tucumania respectively. Finally, we provide an updated key for the identification of Apanteles species recorded parasitizing cactus moth caterpillars in the American continent.

La falta de información sobre plantas hospedantes silvestres de Bactericera cockerelli ha limitado la comprensión de la ecología y fenología del insecto y el papel real de estas plantas en la dinámica de la enfermedad. Debido a la vectorización de la bacteria fitopatógena Candidatus Liberibacter solanacearum (Lso), B. cockerelli es una de las plagas más importantes de cultivos de solanáceas. En este documento, se reporta que B. cockerelli está asociada con una planta huésped silvestre no enlistada, Margaranthus solanaceus Schltdl., en las llanuras bajas del noreste de México. Se recolectaron un total de 37 muestras de plantas Margaranthus en Cadereyta, estado de Nuevo León, México. De éstas se obtuvieron 761 huevos y 129 ninfas (medias de 20.6 ± 1.04 huevos y 3.48 ± 0.4 ninfas por planta). El insecto completó su desarrollo hasta adulto en esta planta. La PCR indicó que tres de 35 plantas examinadas (8,6%) fueron positivas a la infección por Lso; debido a dificultades metodológicas, este porcentaje probablemente esté subestimado. Todos los psílidos adultos (100%) en una muestra (n = 21) que emergieron de Margaranthus y fueron analizados por PCR también fueron positivos a Lso. Este es el primer informe de M. solanaceous como huésped de B. cockerelli, de Lso y de B. cockerelli infectado con Lso. Junto con otros huéspedes silvestres, esta planta puede contribuir a la dinámica poblacional de B. cockerelli y Lso en América del Norte.