Implications of combined taxonomic, morphometric, and molecular characteristics for the species status of Paracentrobia tapajosae and Paracentrobia subflava (Hymenoptera: Trichogrammatidae), egg parasitoids of different leafhopper hosts in the Americas.

The present study evaluated the taxonomy, morphology, and molecular variation of the egg parasitoids Paracentrobia subflava developing within eggs of the corn leafhopper Dalbulus maidis from Mexico, and Paracentrobia tapajosae developing within eggs of Tapajosa rubromarginata and eggs of D. maidis from Argentina. The parasitoids from the different host species were found to have a significant difference in body size and morphology of head, wings, ovipositor, and chaetotaxy. On the other hand, geometric morphometric analysis of the male genitalia showed no difference between parasitoids emerged from T. rubromarginata and D. maidis. Additionally, the COI and ITS2 molecular markers demonstrated that the parasitoids emerging from these two different hosts cluster into a single clade. This new information suggests the placement of P. tapajosae syn. nov. as a junior synonym of P. subflava.

Diversity and Parasitism by Parasitic Wasps That Attack Dalbulus maidis (Hemiptera: Cicadellidae) on Year-Round and Seasonal Maize Agroecosystems.

Agroecosystems undergo frequent anthropogenic disturbance that may affect the diversity, community, and abundance of natural enemies living there. In the tropics, annual crops such as maize are planted two times (year-round crops) or one time (seasonal crops) per year. Little is known about how natural enemies of insect pests respond to maize agroecosystems planted one vs. two times during each annual cycle. The objective was to investigate the diversity and parasitism of egg parasitoids of the pest Dalbulus maidis (DeLong) (Hemiptera: Cicadellidae) in maize agroecosystems planted year-round and seasonally. Potted maize plants with D. maidis eggs were placed within these two maize agroecosystems to attract egg parasitoids during the maize-growing wet season in Mexico. In these two maize agroecosystems, similar levels of diversity were found, using the Shannon-Wiener index (H'). Communities of parasitic wasps were found attacking the eggs of D. maidis in both maize agroecosystems, but there were differences in the composition of these communities. In the year-round maize agroecosystem, Paracentrobia sp. near subflava (Girault) (Hymenoptera: Trichogrammatidae) was the most common, while Anagrus virlai Triapitsyn (Hymenoptera: Mymaridae) was most common in the seasonal maize. A greater total abundance and total rate of parasitoid emergence were found in the year-round maize agroecosystem compared with the seasonal maize. In addition, a positive relationship between the number of D. maidis eggs and parasitoid abundance was found in both maize agroecosystems. However, a negative density dependence between the number of D. maidis eggs and the percentage of parasitism was found in both maize agroecosystems.

Diversity of Planthoppers (Hemiptera: Delphacidae) on Maize Crops and Edge Grasses in Mexico.

Delphacid planthoppers (Hemiptera: Delphacidae) are a group of economically important sap-feeding insects that vector plant pathogens and are pests of crops, such as maize, wheat, and rice. This study was conducted to evaluate planthopper diversity, abundance, and the presence of potential vectors on maize crops and associated edge grass habitats. In Jalisco, west-central Mexico, delphacids were sampled using a sweep net in two different habitats (with and without irrigation) during the dry and rainy seasons of 2013 and 2014. A total of 5,621 specimens were collected and nine species were identified: Metadelphax propinqua (Fieber), Delphacodes koebelei Muir and Giffard, Delphacodes arcuata Beamer, Sogatella kolophon (Kirkaldy), Syndelphax fulvidorsum (Metcalf), Chionomus balboae (Muir & Giffard), Toya idonea (Beamer), Syndelphax humilis (Van Duzee), and Tagosodes cubanus (Crawford) (Hemiptera: Delphacidae), all belonging to the tribe Delphacini (Delphacinae). A high diversity of delphacids was found in the edge grasses during the dry season and rainy season. Planthopper abundance was higher in the edge grasses than in the maize fields during the rainy season. The most abundant species was M. propinqua representing 67.5% of the specimens collected. Populations of M. propinqua in edge grasses peaked during the dry season in December and January. Metadelphax propinqua, S. kolophon, and T. cubanus are known to be potential plant pathogen vectors.

Egg Parasitoids of Dalbulus maidis (Hemiptera: Cicadellidae) Within Maize Agroecosystems and in the Edge Zones of Maize Fields, and on Maize Varieties During the Wet Season in Mexico.

Little is known about Dalbulus maidis (DeLong) egg parasitoids within maize fields, in the edge zones that surround these fields, and the parasitism on D. maidis eggs oviposited on different maize varieties. The objectives of the present study were first to understand which egg parasitoid species attack D. maidis eggs within maize fields and in the surrounding edge zones, and second, to compare parasitism on two maize varieties (land race Ancho-pozolero and hybrid Tigre-Asgrow) during the maize-growing wet season. We used maize plants with sentinel eggs to attract the egg parasitoids in two consecutive wet seasons, in 2015 and 2016. In 2015, Anagrus sp. (Hymenoptera: Mymaridae) and Paracentrobia sp. (Hymenoptera: Trichogrammatidae) parasitized D. maidis eggs within the maize field and on its edges. However, much more parasitism was seen within the maize agroecosystem than in the maize edge zones. In 2016, two Mymaridae species, Anagrus columbi Perkins and Anagrus sp, and two Trichogrammatidae genera, Pseudoligosita sp. and Paracentrobia sp., attacked the D. maidis eggs laid on maize hybrids but not those oviposited on the maize land race. Our findings indicate that parasitism of corn leafhopper eggs differs with agroecosystem location and maize varieties.

Egg parasitoids of the corn leafhopper, Dalbulus maidis, in the southernmost area of its distribution range.

Egg parasitoids of the corn leafhopper, Dalbulus maidis (DeLong and Wolcott) (Hemiptera: Cicadellidae), were surveyed exposing sentinel eggs of the leafhopper along a latitudinal transect of 600 km in Argentina, the southernmost area of its distribution range. Four parasitoid species were obtained: the mymarids Anagrus breviphragma Soyka (Hymenoptera: Mymaridae), Anagrus flaveolus Waterhouse, and Polynema sp., and the trichogrammatid Pseudoligosita longifrangiata (Viggiani) (Hymenoptera: Trichogrammatidae). The low parasitism rate, low species richness, and high proportion of generalist egg parasitoids were quite clear in the southern distribution limit of the vector, in contrast to regions where corn crops are available all year round and there are continuous and overlapping generations of the pest. Further studies need to be done in order to determine the native host of the above egg parasitoids, the seasonal abundance, and the possible occurrence of other species affecting D. maidis populations in the studied area.

First record of Eudorylas schreiteri (Shannon) (Diptera: Pipunculidae) as a parasitoid of the corn leafhopper (Hemiptera: Cicadellidae) in Argentina, with a table of pipunculid-host associations in the neotropical region.

The big-headed fly Eudorylas schreiteri (Shannon) is recorded for the first time as an endoparasitoid of the corn leafhopper Dalbulus maidis (DeLong & Wolcott) in Northern Argentina. A table of known Neotropical pipunculid-host associations is presented.

First record of Eudorylas schreiteri (Shannon) (Diptera: Pipunculidae) as a parasitoid of the corn leafhopper (Hemiptera: Cicadellidae) in Argentina, with a table of pipunculid-host associations in the neotropical region / Primeiro registro de Eudorylas schreiteri (Shannon) (Diptera: Pipunculidae) como parasitóide da cigarrinha do milho (Hemiptera: Cicadellidae) na Argentina, e uma tabela dos hospedeiros de pipunculídeos na região neotropical

The big-headed fly Eudorylas schreiteri (Shannon) is recorded for the first time as an endoparasitoid of the corn leafhopper Dalbulus maidis (DeLong & Wolcott) in Northern Argentina. A table of known Neotropical pipunculid-host associations is presented.

Eudorylas schreiteri (Shannon) é registrada pela primeira vez como endoparasitóide da cigarrinha do milho Dalbulus maidis (DeLong & Wolcott) no norte da Argentina. Uma tabela das espécies neotropicais de pipunculídeos com hospedeiros conhecidos é apresentada.

Positive effects of shade and shelter construction by ants on leafhopper-ant mutualism.

The myrmecophilous five-spotted gamagrass leafhopper, Dalbulus quinquenotatus DeLong and Nault, and its tending ants on gamagrass Tripsacum dactyloides L. were examined to determine the influence of shade and ant-constructed shelters on the population sizes of D. quinquenotatus and ants. Gamagrass plants hosting ants and leafhoppers were exposed to 50, 30, or 0% artificially constructed shade. The greatest numbers of leafhoppers and ants were found on plants that received 50% shade. Shelters made by the ant Solenopsis geminata (F.) contained large numbers of leafhoppers and ants but were found only on T. dactyloides exposed to 50% shade in artificially constructed habitats. Additional sampling was conducted on wild gamagrass plants in the field to explore the presence of ants tending leafhoppers in shelters and to evaluate whether ant-constructed shelters protect leafhopper nymphs from parasitoid wasps. Large aggregations of S. geminata in shelters were also found in natural gamagrass habitats. Leafhopper nymphs living in shelters made by S. geminata may be protected against the dryinid wasp parasitoid Anteon ciudadi Olmi. No sheltered nymphs were parasitized by dryinids, whereas 24% of unsheltered nymphs had dryinid parasitism.

Habitat of the corn leafhopper (Hemiptera: Cicadellidae) during the dry (winter) season in Mexico.

Although the corn leafhopper Dalbulus maidis (DeLong and Wolcott) is the most important vector of maize pathogens in Latin America, little is known about how and where it overwinters (passes the dry season), particularly in Mexico. The objectives of this study were (1) to monitor the abundance of D. maidis adults throughout the dry season in maize and maize-free habitats and (2) to determine where and how D. maidis adults, exposed or nonexposed to the maize pathogen Spiroplasma kunkelii Whitcomb, overwinter in a maize-free habitat. Work for the first objective was done during the two consecutive dry seasons of 1999-2000 and 2000-2001; the second objective was done during the dry seasons of 2003-2004 and 2005-2006. During the dry winter seasons, D. maidis was prevalent as long as maize was present in irrigated areas. The leafhopper was found in 52 of the 58 irrigated maize fields sampled in Mexico at the end of the dry seasons of 1999-2000 and 2000-2001. However, leafhopper adults were not found in nonirrigated maize-free habitats at high elevation during the dry winter season (February, March, and April), although leafhopper adults were prevalent on perennial wild grasses in January after maize harvest. Additional experiments revealed, however, that corn leafhopper adults, although few in number, survived the entire dry season in these nonirrigated maize-free fields. Also, no detectable difference in survival existed between leafhoppers exposed and those not exposed to S. kunkelli during the two dry seasons in the maize-free habitat.