Abundance and Species Richness of Leafhoppers and Planthoppers (Hemiptera: Cicadellidae and Delphacidae) in Brazilian Maize Crops

Fil: De Oliveira, Charles Martins. Embrapa Cerrados. Planaltina. Brasília/DF; BrazilFil: De Oliveira, Elizabeth. Embrapa Milho e Sorgo. Sete Lagoas/MG; BrazilFil: Prazeres De Souza, Isabel Regina. Embrapa Milho e Sorgo. Sete Lagoas/MG; BrazilFil: Alves, Elcio. DuPont do Brazil S.A. DivisÆo Pioneer Sementes. Itumbiara/GO; BrazilFil: Dolezal, William. Pioneer Hi-Bred International. Itumbiara/GO; BrazilFil: Paradell, Susana Liria. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Marino de Remes Lenicov, Ana María. División Entomología. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Frizzas, Marina Regina. Universidade de Brasília. Departamento de Zoologia. Instituto de Ciências Biológicas. Brasília/DF; Brazi

The species of Megaphragma Timberlake (Hymenoptera: Trichogrammatidae) from Argentina

Trichogrammatidae are an almost worldwide family of egg parasitoids that consist of 88 genera (Pinto 2006). Species of Megaphragma Timberlake (tribe Oligositini) are egg parasitoids of Thysanoptera. Fifteen species are assigned to Megaphragma, but only three have been reported from the Neotropical region (Noyes 2002). Megaphragma mymaripenne Timberlake (1924) has been recorded previously from Argentina (De Santis 1970), but M. striatum Viggiani (1997) was known only from Mexico, and M. caribea Delvare (1993) is known only from Guadeloupe (Noyes 2002; Pinto 2006). Recently, one of us (E. Luft) reared Megaphragma sp. from eggs of Thysanoptera on corn in San Miguel de Tucumán, Argentina, and this record instigated a review of all material of the genus recorded from Argentina. We searched for specimens deposited in the major entomological collections of Argentina: Instituto Fundación Miguel Lillo (San Miguel de Tucumán) (IMLA), Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (Buenos Aires city) (MBA), and Museo de Ciencias Naturales de La Plata (La Plata, Buenos Aires province) (MLPA), but found specimens only in MLPA. In addition, one of us (G. Viggiani) studied material of Megaphragma from Argentina preserved in two other collections, that of the University of California Riverside (UCR) and of the Universidad Rómulo Gallegos, Venezuela (URGV). The results of this study are presented here.Fil: Viggiani, Gennaro. Università degli Studi di Napoli Federico II; ItaliaFil: Luft Albarracin, Erica Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; ArgentinaFil: Virla, Eduardo Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Planta Piloto de Procesos Industriales Microbiológicos; Argentin

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

Estimation of direct damage to maize seedlings by the corn leafhopper,<i>Dalbulus maidis</i>(Hemiptera: Cicadellidae), under different watering regimes

AbstractThe corn leafhopperDalbulus maidis(Hemiptera: Cicadellidae), a specialist herbivore, is the cause of serious losses in maize yield for its capacity to transmit three important plant pathogens. They are also active phloem feeders, that insert stylets into the plant as they feed. Females place their eggs endophytically, totally inserted in the central midrib or the leaf blades, leaving conspicuous openings in the place where the ovipositor was inserted. In spite of the consequences that feeding and oviposition may have on the water status of the plant and the production of biomass, direct damage caused by the leafhopper has been only scarcely studied. In the present contribution, we measured biomass loss due to direct damage in maize plants under two watering regimes, with water supplyad libitumand with a watering restricted regime, emulating the most frequent field conditions. Moreover, we analyzed the effects of increasing densities of the vector on the biomass loss and plant mortality and the effects of females vs males. We observed that a density of 10 insects is sufficient to cause damage to 10-day-old seedlings, even in anad libitumwatering regime; however, in drought conditions, damage can be significantly greater, causing plant mortality. Also, females cause more damage than males, due to their oviposition habits.</jats:p