Natural enemies and their impact on Diuraphis noxia (Mordvilko) (Hemiptera: Aphididae) populations

Abstract

The influence of natural enemies on the population growth of Diuraphis noxia (Mordvilko) in wheat fields in eastern South Africa was investigated. Since the natural enemies were not present in the initial stages, the apparent mortality observed must have been due to other causes. During the logarithmic phase of aphid population growth, predators, in particular the coccinellid Hippodamia variegata (Goeze), had a slight inhibitory effect on growth. During the decline phase of the aphid population, the potential population size was reduced by as much as 52% by predation. The most abundant parasitoids, Aphidius colemani Viereck and Diaeretiella rapae (M'Intosh), had a negligible effect. Although natural enemy populations showed functional responses to increases in Diuraphis noxia numbers, they did not prevent the latter from attaining and exceeding economic injury levels.

Overlapping oviposition and chemical defense of eggs in two co-occurring species of ladybird predators of aphids

“…This conclusion is consistent with the earlier findings that show ladybird predators often share common food resources and synchronize their numerical (Tamaki and Long 1978;Frazer et al 1981;Aalbersberg et al 1988). As a consequence, interspecific interaction in aphid patches shared by two or more species of predators is a reality (Agarwala and Bardhanroy 1997;Hironori and Katsuhiro 1997;Agarwala et al 1998;Obrycki et al 1998;Taylor et al 1998;Takizawa et al 2000).…”

An overview of the context and scope of wheat (Triticum aestivum) research in South Africa from 1983 to 2008

“…Yield losses due to D. noxia are severe with possible individual plant losses as high as 90% (Walters, 1984 (Marasas et al, 1997;Tolmay et al, 2000) that has been actively researched and promoted to this day. This strategy has encouraged the use of a variety of natural enemies of the aphid such as parasitic wasps (Prinsloo, 1998;2000;Prinsloo & Du Plessis, 2000), predators (Aalbersberg et al, 1988) and entomopathogenic fungi (Hatting et al, 1999;2000;, in support of D. noxia resistant cultivars, which have formed the backbone of the control programme. One of these parasitic wasps namely Aphelinus hordei, was introduced from the Ukraine in 1991.…”

Effects of intra and interspecific interactions on the survival of two predatory ladybirds (Coleoptera: Coccinellidae) in relation to prey abundance

“…Menge and Sutherland, 1987;Begon et al, 1996). Intraguild predation is common among arthropods in agricultural (Rosenheim et al, 1993(Rosenheim et al, , 1995Cisneros and Rosenheim, 1997) and natural ecosystems (Moran and Hurd, 1994;Snyder and Hurd, 1995); therefore, intraguild predation is thought to be an important factor affecting population dynamics and community structure in several taxa of predatory arthropods (Polis et al, 1989;Spence and Carcamo, 1991;Polis and Holt, 1992;Fincke, 1994;Wagner and Wise, 1996; Holt and Polis, 1997;Mizell, 2007;Montserrat et al, 2008).Many species of predatory arthropods are attracted to sites where aphids are abundant (Sakuratani, 1977;Aalbersberg et al, 1988;Winder et al, 1994;Wyss, 1995;Nakashima and Akashi, 2005;Alhmedi et al, 2007). In these aphidophagous guilds, intraguild predation often occurs and its incidence depends on prey abundance and the developmental stages and species of the predator involved (Takahashi, 1989;Agarwala and Dixon, 1992; Rosenheim et al, 1993;Cisneros and Rosenheim, 1997;Dinter, 1998;Lucas et al, 1998;Obrycki et al, 1998;Phoofolo and Obrycki, 1998).…”

“…Many species of predatory arthropods are attracted to sites where aphids are abundant (Sakuratani, 1977;Aalbersberg et al, 1988;Winder et al, 1994;Wyss, 1995;Nakashima and Akashi, 2005;Alhmedi et al, 2007). In these aphidophagous guilds, intraguild predation often occurs and its incidence depends on prey abundance and the developmental stages and species of the predator involved (Takahashi, 1989;Agarwala and Dixon, 1992; Rosenheim et al, 1993;Cisneros and Rosenheim, 1997;Dinter, 1998;Lucas et al, 1998;Obrycki et al, 1998;Phoofolo and Obrycki, 1998).…”