Effect of prey density on the functional and numerical responses of two species of predaceous mites (Acari: Phytoseiidae)

Abstract

Efeito da Densidade de Presa nas Respostas Funcional e Numérica de Duas Espécies deÁcaros Predadores (Acari: Phytoseiidae)RESUMO -Ácaros da família Phytoseiidae são os inimigos naturais de ácaros-praga mais importantes e estudados. Uma questão freqüentemente levantada é se os fitoseídeos podem reduzir altas densidades de ácaros fitófagos a baixos níveis. PALAVRAS-CHAVE: Iphiseiodes zuluagai, Euseius alatus, Brevipalpus phoenicis, citros, cafeeiroABSTRACT -Phytoseiidae mites are the most important and studied natural enemies of pest mites. A question frequently raised is whether phytoseiid may reduce high densities of phytophagous mites. Studies of functional and numerical responses may help to answer this question. The aim of this work was to evaluate the potential predation success of Iphiseiodes zuluagai Denmark and Muma and Euseius alatus DeLeon (Acari: Phytoseiidae) on Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae), vector of the citrus leprosis and the coffee ringspot viruses. Bioassays were performed in the laboratory. Adult females of each predator were isolated in arenas made with citrus leaves (3-cm diameter). Immature stages of B. phoenicis were offered as prey, at the following numbers/arena: 1, 2, 5, 10, 20, 30 and 35 (seven replicates), 45 (four replicates), 55 (three replicates) and 70, 100, 125, 200 and 300 (two replicates). The number of killed prey and of eggs laid by the predators was evaluated every 24h, during eight days. Killed prey was replaced daily by new prey. For both predatory mites, a positive and highly significant correlation was found between the numbers of prey offered and killed. The average daily oviposition rate also increased with the number of killed prey. At the lower densities, E. alatus killed and ate more B. phoenicis than I. zuluagai. The opposite was observed at the highest densities. It is possible that E. alatus can reduce B. phoenicis population even at low prey densities, and I. zuluagai can do the same also at high densities. The fact that E. alatus requires less prey than I. zuluagai suggests that its survivorship may be higher than that of I. zuluagai at low prey densities. KEY WORDS: Iphiseiodes zuluagai, Euseius alatus, Brevipalpus phoenicis, citrus, coffee plant 462Reis et al.

Predatory Potential of <i>Phytoseiulus macropilis</i> (Banks) Preying on <i>Tetranychus urticae</i> Koch (Acari: Phytoseiidae, Tetranychidae)

“…The results found in the present study, about increase of female oviposition with de increase of prey density, are similar to those found in a study on the effect of Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) density in the functional and numerical response of Euseius alatus DeLeon and Iphiseiodes zuluagai Denmark and Muma [18]; additionally, to the results of the study on Euseius concordis (Chant) functional and numerical response [33]; finally to the results of the evaluation of E. alatus predation potential [34]. All of these mites are phytoseiids, like P. macropilis in this work.…”

“…in the replications occurred due to the large number of mite specimens that were necessary in the highest densities [18].…”

Life table and predation rates of the syrphid fly Allograpta exotica, a control agent of the cowpea aphid Aphis craccivora

“…This relationship has been defined as the functional response (Solomon, 1949) and it is one of the most important factors in the population dynamics of predator-prey systems (Schenk and Bacher, 2002). The functional response concept was first described by Holling (1959) and has been widely used to evaluate and predict the potential effectiveness of predators as BCAs (Laing and Osborn, 1974;Everson, 1980;Sabelis, 1985;Trexler et al, 1988;De Clercq et al, 2000;Badii et al, 2004;Reis et al, 2003Reis et al, , 2007Sepúlveda and Carrillo, 2008;Timms et al, 2008;Hassanpour et al 2009). …”

Perspectivas para a criação massal de Iphiseiodes zuluagai Denmark & Muma (Acari: Phytoseiidae)

“…zuluagai é um predador capaz de explorar diversas fontes de alimento (Yamamoto & Gravena 1996;Reis et al 1998Reis et al , 2003, podendo ser classifi cado como predador tipo III (McMurtry & Croft 1997). O fato de I. zuluagai alimentar-se de Astigmata amplia o conhecimento sobre as fontes alimentares disponíveis para ele.…”

“…Em laboratório, I. zuluagai mostrou-se bastante efi ciente como predador de B. phoenicis (Reis et al 2003), podendo ainda se alimentar de pólen e substâncias açucaradas (Yamamoto & Gravena 1996, Reis et al 1998, características desejáveis para um agente de controle biológico, pois propicia sua criação sobre fontes de alimento alternativas.…”