Food webs, risks of alien enemies and reform of biological control.

Abstract

As ilwasions of alien species mount, biological control ''''ill become an increasingly important tool of conservation and agriculture. In an effort to understand indirect interactions in biological control, we review food web ecology in terms of resource competition, trophic cascades, intra-guild predation, apparent competition, omnivory and a diverse set of tri-trophic interactions. The most inclusive study suggests that food webs in biological control are simpler than in natural communities. Risks to non-target species created by biological control have been studied seriously for only about 20 years, and knowledge of these risks is incomplete. The greatest risks are known to be posed by the organisms with the broadest diets, such as vertebrates and the snail Euglandina rosea, which has probably caused the extinction of an entire genus of native snails in Polynesia. Some parasitoid species have been introduced that are sufficiently polyphagous to attack native insects, and cases of serious harm to non-target populations are now coming to light. However, polyphagous organisms continue to be imported for biological control. One case in point is the campaign against the Russian wheat aphid, in which over 8.5 million individual invertebrates, including more than 1 million individuals of 12 species of ladybird beetles new to North America, were released over the past 15 years, with little study of potential non-target effects, direct or indirect. Another case is the new use of the polyphagous black carp for suppression of pest snails in industrial catfish ponds. This fish poses great risks to the high native diversity of molluscs in the Mississippi drainage. We argue that risk to native flora in

Benefits and limitations of factitious prey and artificial diets on life parameters of predatory beetles, bugs, and lacewings: a mini-review

“…Unfortunately, generalist (polyphagous) predators have come under tremendous scrutiny because of concerns of the potential adverse effects they might pose to the environment (Strong and Pemberton 2001;van Lenteren et al 2003b;Stiling 2004;Snyder and Evans 2006). Accumulating evidence suggests that certain generalist, exotic species have the potential to out-compete native species, leading to localized extirpation of some populations (De Clercq 2002).…”

Trait‐mediated interactions and lifetime fitness of the invasive plant Centaurea solstitialis

“…The principle risk of biocontrol is nontarget attack, i.e., when an agent attacks native and/or agricultural species, and much attention has deservedly been paid to this topic (e.g., Louda and Potvin 1995, Simberloff and Stiling 1996, Strong and Pemberton 2001. The principle risk of biocontrol is nontarget attack, i.e., when an agent attacks native and/or agricultural species, and much attention has deservedly been paid to this topic (e.g., Louda and Potvin 1995, Simberloff and Stiling 1996, Strong and Pemberton 2001.…”

Measuring and evaluating ecological outcomes of biological control introductions

“…In his classic book, DeBach (1974) makes reference to periodic censuses and life tables, but he recommends against such methods on the grounds that they cannot prove cause and effect, and instead he advocates for experimental assessments of control agent effectiveness using exclusion (see Chapter 9). The reason for the lack of such work in the recent literature is not entirely clear to me, but use of demographic assessments could have prevented the ill-advised addition of more and more coccinellid predators to control pest aphids (Caltagirone, 1989;Obrycki and Kring, 1998;Rosenheim, 1998;Obrycki et al, 2000), or releases of unstudied, often taxonomically unknown or undefined, species of parasitoids, predators, and fungi, with the vast majority not establishing and none providing satisfactory control (Strong and Pemberton, 2001;Havill et al, 2012;Stehn et al, 2013). The reason for the lack of such work in the recent literature is not entirely clear to me, but use of demographic assessments could have prevented the ill-advised addition of more and more coccinellid predators to control pest aphids (Caltagirone, 1989;Obrycki and Kring, 1998;Rosenheim, 1998;Obrycki et al, 2000), or releases of unstudied, often taxonomically unknown or undefined, species of parasitoids, predators, and fungi, with the vast majority not establishing and none providing satisfactory control (Strong and Pemberton, 2001;Havill et al, 2012;Stehn et al, 2013).…”