Froghopper

Abstract: The objective of this work was to evaluate the efficiency of some insecticides for controlling root froghopper, Mahanarva fimbriolata (Stal), and their effects on sugarcane quality and yield. Two experiments were carried out under field conditions to test the insecticides imidacloprid at 480, 720 or 960 g of active ingredient (AI).ha-1, aldicarb at 1,200 or 1,500 g AI.ha-1 and thiamethoxam at 150 or 200 g AI.ha-1, in comparison with the control (without insecticide). In one of the experiment, the treatments were applied when root froghopper infestation was 3.4 insects per meter. In this experiment, imidacloprid and thiamethoxam reduced pest infestations for at least 121 days. In another experiment, the insecticides were applied when froghopper infestation was 9.6 insects per meter. Best control was obtained with aldicarb at 1,500 g AI.ha-1 while thiamethoxam and imidacloprid reduced pest infestations only when they were applied at higher doses. The reduction of pest infestation with insecticides applications did not affect the sugar content in the stalks or fiber, but increased the sugarcane yield, reaching values up to 15.3 t.ha-1.

Abstract: Resistance to an endophyte, Acremonium coenophialum Morgan-Jones & Gams, and management tactics were evaluated against several leafhopper species under field conditions. ‘Georgia-5’ tall fescue, Festuca arundinacea Schreb., was planted to a randomized block design split plot with a factorial arrangement of pest management treatments in the subplot. Leafhopper and froghopper populations were monitored throughout the year by taking sweep samples approximately every 2 wk. Of the 28 species of leafhoppers and froghoppers collected, 6 species of leafhoppers and 1 species of froghopper comprised over 80% of the specimens collected. With the exception of the nematicide treatment, there was no significant difference in leafhopper population densities due to chemical treatments. Four species of leafhoppers and one species of froghopper showed significantly higher population densities on endophyte-free tall fescue when compared with the endophyte-infected tall fescue plots. The greatest differences between endophyte-free and endophyte-infected tall fescue plots occurred at leafhopper peak seasonal densities. Although chemical treatments apparently have little effect on leafhopper population densities, the Acremonium endophyte provides tall fescue with resistance against some leafhopper species.

Abstract: Male-specific associations of adult froghoppers (Homoptera: Cercopidae) with alternative food plant hosts is reported. Four accounts from the field and one from the literature are presented: Iphirhina quota on Bourreria costaricensis (Boraginaceae), Huaina inca on Solanaceae sp., Prosapia simulans and Prosapia sp. (near 1 bicincta) on Ilex haberi (Aquifoliaceae), and Prosapia bicincta on Ilex cornuta and Ilex opaca. In three cases host use is limited to adults while in two cases use is limited to only adult males. In four cases adults feed on plants that differ taxonomically, structurally and ecologically from hosts normally utilized by all life stages. These associations are not considered aggregations per se because froghoppers are not clustered and because these associations cannot be explained by the usual criteria supporting the adaptiveness of insect aggregations. Indirect evidence suggests that these unusual hosts may be unavailable to nymphs and not sought by females. This passive lack of opportunity by nymphs and females, in tandem with an active selection/attraction by males, is a plausible explanation for the existence of male-specific hosts. RESUMEN Se reportan asociaciones machos-especlficas de los cercopidos adultos (Homoptera: Cercopidae) con plantas hospederas. Se presentan cuatro casos de campo y uno de la literatura: Iphirhina quota sobre Bourreria costaricensis (Boraginaceae), Huaina inca sobre Solanaceae sp., Prosapia simulans y Prosapia sp. (relacionado a ? bicincta) sobre Ilex haberi (Aquifoliaceae), y Prosapia bicincta sobre Ilex cornuta e Ilex opaca. En tres casos el uso del huesped esta' limitado a los adultos mientras en dos casos el uso esta' limitado a los adultos machos. En cuatro casos los adultos se alimentan de plantas que se diferencian taxonomica, estructural y ecologicamente de los hospederos que utilizan normalmente en todos los estados de vida. Estas asociaciones no estan consideradas como agregaciones per se porque los adultos no se agrupan y porque no pueden ser explicadas por los criterios usuales que apoyan la adaptividad de agregaciones de insectos. Evidencia indirecta sugiere que estos hospederos inusuales pueden estar indisponibles para las ninfas y no ser buscados por las hembras. Esta pasiva falta de oportunidad para las ninfas y hembras, en combinacion con la activa seleccion/ atraccion por los machos, es una explicacion posible para la existencia de hospederos macho-especificos.

Abstract: Egg parasitism by the microhymenopteran Anagrus urichi Pickles was found on samples of spittlebug eggs collected in Brachiaria decumbens pasture. It is the first record of spittlebug egg parasitism for the State of Mato Grosso do Sul, Brazil. The rate of 10.4% of parasitism was observed in 1688 spittlebug eggs, comprising seven samples. On average, 4.7 wasps emerged from each parasitized egg. Thirteen percent of parasitism were observed when 100 eggs of the spittlebug Notozulia entreriana (Berg), obtained in the laboratory, were exposed to eight of these parasitoids. It is anticipated the possibility of mass rearing A. urichi.