Theoretical contributions to biological control success

Abstract

Ecologists have long tried, with little success, to develop ecological theory for biological control. Biological control illustrates how science often follows, rather than precedes, technological advances. A scientific theory of biological control remains a worthy and achievable goal. We need to (1) combine deductions from mathematical models with rigorous empiricism measuring and modeling the effects of abiotic and biotic environmental drivers on demography and population dynamics of real biological control systems in the field, (2) use a wider range of model systems to explore how population structure, movement, spatial heterogeneity, and external environmental conditions influence population and community dynamics, and (3) combine deductive and inductive approaches to address the day-to-day concerns of biocontrol scientists including how to rear and release a control organism, suppress the target organism, and minimize harm to non-target organisms. Further progress will require more fundamental research in population and community ecology directly relevant to biological control.

Pest kill rate as aggregate evaluation criterion to rank biological control agents: a case study with Neotropical predators of Tuta absoluta on tomato

“…Many suggestions about biocontrol agent selection have been published, ranging from quick fits like the collection and release of any natural enemy that might attack the pest (the ‘hit or miss approach’; DeBach, 1964), to rather time-consuming research programmes which include behavioural and ecological studies, as well as environmental risk assessments (van Lenteren, 1980; van Lenteren & Woets, 1988; van Driesche & Bellows 1996; Stiling & Cornelissen, 2005; van Lenteren et al ., 2006; Heimpel & Mills, 2017; McEvoy, 2018). Often it takes about 10 years to find, evaluate, select and eventually market a natural enemy, which is similar to the time needed to find a new synthetic pesticide.…”

Biocontrol of invasive weeds under climate change: progress, challenges and management implications

“…For example, based on habitat suitability in SDMs, the invasive plant Ambrosia artemisiifolia L. is predicted to experience decreased geographic overlap with six biocontrol candidates under climate change in its introduced European range [38 ]. SDMs can also use climate suitability to predict demographic rates and the ability of biocontrol agents to quickly attain high population densities, which are critical for significant impacts on the target plant invader [39] and management success [40]. Moreover, combining SDM and mechanistic (process-based) models by integrating physiological models of insect development into SDMs based on habitat suitability may enable more robust predictions of both range shifts [41] and population abundances [42,43].…”

An Alternative Perspective for the Theory of Biological Control

“…does provide evidence for local stability [21], but the introduction of the cinnabar moth ( Tyria jacobaeae (L.)) and the ragwort flea beetle ( Longitarsus jacobaeae (Waterhouse)) for control of tansy ragwort ( Jacobaea vulgaris (Gaertn.)) provides evidence of instability at a local scale [9]. In addition, Murdoch et al [22] found no evidence for local stability in the parasitoid–host interactions associated with successful biological control of winter moth, olive scale, larch sawfly, and walnut aphid.…”

“…Perhaps the most disappointing aspect of this historical record is that although a theoretical explanation for success versus failure has been “a relentlessly pursued but elusive goal” [7], it has achieved “few if any, general principles, or even rules of thumb, to guide the efforts of biological control” [8]. McEvoy [9] makes a compelling case for the potential of ecological theory to improve the effectiveness and safety of biological control, and for this study, the author considered why attempts to develop a predictive theory for biological control have been misguided and what future directions might be more promising and effective.…”