Predation by ground beetles and wolf spiders on
herbivorous insects in a maize crop
Andreas Lang
a,1,*
, Juliane Filser
a
, Johannes R. Henschel
b
a
GSF-Forschungszentrum fu
È
r Umwelt und Gesundheit, Institut fu
È
r Bodeno
È
kologie, Neuherberg,
Postfach 1129, D-85758, Oberschleiûheim, Germany
b
Desert Ecological Research Unit, P.O. Box 953, Walvis Bay, Namibia
Received 25 May 1998; accepted 28 October 1998
Abstract
Ground beetles (Carabidae) and wolf spiders (Lycosidae) are among the dominant epigeal arthropod predators in arable land.
Their predation effect on potential insect populations was examined in a maize ®eld. The abundance and effects of ground
beetles and wolf spiders were manipulated by removal or addition within ®eld enclosures during two study periods, mid-
season and end-season. Both Carabidae and Lycosidae depressed populations of Cicadellidae and Thysanoptera, and a
reduction of Aphididae was indicated in mid-season. The results indicated a size-dependent predation effect of Carabidae on
Cicadellidae, the highest predation being on Cicadellidae with a body length above 1.1 mm. There was no strong evidence that
the predation changed with the season. The present study con®rmed that ground beetles and wolf spiders may play an
important role in controlling herbivore populations in agricultural ®elds, and revealed their potential to limit Cicadellidae and
Thysanoptera in maize ®eld. # 1999 Published by Elsevier Science B.V. All rights reserved.
Keywords: Carabidae; Lycosidae; Natural enemies; Generalist predators; Herbivores; Agroecosystem
1. Introduction
Understanding the population dynamics of insects
is of major interest in agroecosystems for controlling
pest outbreaks. Predation by natural enemies, which
control pest organisms has received much attention,
especially under reduced management intensity,
aimed at reducing pesticide applications. Generalist
predators are thought to be important, because, unlike
specialized enemies, they persist in the crop during
periods of low pest density and can prevent early
season build-up of pest numbers (Curry, 1993).
The soil surface-dwelling ground beetles (Carabi-
dae) and wolf spiders (Lycosidae) are common and
abundant predators in agroecosystems (Ekschmitt
et al., 1997). These generalist predators are considered
to be capable of reducing population densities of
insect populations (e.g. Riechert and Lockley, 1984;
Luff, 1987). Evidence provided by gut content ana-
lyses, ®eld observations, and laboratory studies show
that ground beetles and wolf spiders are true general-
ists feeding on many insect taxa (e.g. Sunderland,
1975; Hengeveld, 1980; Nyffeler et al., 1994), and
Agriculture, Ecosystems and Environment 72 (1999) 189±199
*Corresponding author. Tel.: +49-89-5902-616; fax: +49-89-
5902-461; e-mail: lang@biologie.de
1
Present address: Zoologisches Institut der Universita
È
t, Ludwig-
Maximilians-Universita
È
t, Karlstr. 25, D-80333 Mu
È
nchen, Germany.
0167-8809/99/$ ± see front matter # 1999 Published by Elsevier Science B.V. All rights reserved.
PII: S0167-8809(98)00186-8