Quantitative methods for detecting invertebrate predation occurring in the field

Abstract

S U M M A R Y ( I ) Brief descriptions are given of methods that can be used either to determine the mortality caused by a complex of predators to a single target prey species or to quantify the diet of a single target predator species.(2) The following methods can be used quantitatively; direct observation, field caging, recovery of labelled prey, electrophoresis, single radial immunodiffusion, rocket immunoelectrophoresis, enzyme-linked immunosorbent assay.(3) The following methods have potential for quantitative use; faecal analysis, gut dissection, tube precipitin test, ring test, Oakley-Fulthorpe test, crossed immunoelectrophoresis, crossover immunoelectrophoresis, fluorescence immunoassa ys.(4) The following tests are likely to remain qualitative; chromatography, doublediffusion, immunofixation, standard immunoelectrophoresis, latex agglutination, passive haemagglutination inhibition assay, complement fixation test.( 5 ) Examples are given of the use of these tests in predation studies.(6) Precautions associated with the use of these methods are described. (7) Various equations are reviewed for estimating predation rates using data on predator density, proportion positive and detection period in post-mortem tests.(8) There are limitations to the use of all current methods. Direct observation and field caging are of restricted application and often involve disturbance to the system being studied. Faecal analysis and post-mortem methods can confuse scavenging and secondary consumption with predation and they measure biomass ingested rather than number of prey killed or injured. Recovery of labelled prey has the faults of all these methods.(9) Potential new techniques are described for determining, from an examination of its gut contents, what a predator has eaten, when it ate it and in what quantity. I N T R O D U C T I O NIn both pure and applied entomology and ecology there is often a requirement to quantify predation occurring in the field. The aim of this paper is to review available methods to determine (i) which can, and have been, used quantitatively (ii) which have potential for quantitative use (iii) what precautions and limitations are associated with their use and (iv) what are the potential future developments for improving the accuracy of quantification. The review does not include methods that provide evidence of an effect of predators on a prey population whilst not actually quantifying predation (e.g. exclusion techniques, insecticidal 0 1988 Association of Applied Biologists 202 K . D . S U N D E R L A N D check method). These are covered in reviews by Kiritani & Dempster (1973), Southwood (1978) and Grant & Shepard (1985). Direct observation and field caging methods provide information that relates directly to predation, but other methods measure consumption. The latter methods can, however, be used to estimate predation rates, if additional data are available from laboratory and field observations on the proportion of consumption attributable to predation and scavenging. Laboratory observat...

Detecting arthropod intraguild predation in the field

“…Earlier methods include direct observation of predation and visual identification of gut contents involving the use of a microscope. More recently, immunological, chemical and isotopic techniques (Kiritani and Dempster 1973;Sunderland 1988;Harwood and Greenstone 2008), have been used to deduce the diet of coccinellids and other aphids predators (reviewed in Harwood and Obrycki 2005;Weber and Lundgren 2009a). In the context of identifying IGP by arthropods, three methods are of particular interest: the use of monoclonal antibodies, gas chromatography mass spectrometry (GC-MS) and a DNA based approach.…”

Conservation and evaluation of natural enemies in IPM systems for Bemisia tabaci

“…Based on gut-content results and predator population density, Naranjo and Hagler (1998) identified O. tristicolor, L. hesperus, and G. punctipes as the most prevalent predators of B. tabaci eggs. Unfortunately, because of limitations of the technique, it is not possible to estimate quantitative rates of predation by these species (Sunderland, 1988;Hagler and Naranjo, 1996). Life table analyses provide a detailed description of the mortality forces affecting a population and allow direct estimation of the probability of dying and the causes of death.…”

“…A number of excellent reviews have addressed the general area of natural enemy evaluation for all approaches to biological control (Kiritani and Dempster, 1973;DeBach et al, 1976;Luck et al, 1988;Sunderland, 1988;Kidd and Jervis, 1996). Briefly, methods can be categorized as (1) addition of natural enemies to an area from which they are absent, (2) population census and correlation (3) exclusion or inclusion of natural enemies, usually using some sort of cage, (4) interference or removal of natural enemies by trapping, hand-picking, or more typically, use of insecticides, (5) a variety of methods that measure natural enemy feeding activity such as gut content analyses, and (6) life tables and other direct observation techniques that attempt to measure sources and rates of mortality.…”

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“…Ecologists have used a variety of immunological methods to study predation. [1][2][3][4][5][6][7] The methods are based on the common principle that antibodies raised in rabbits against predated species can be used to detect antigens of that species in the gut contents of predators. In determining the predatory role of backswimmers against mosquito larvae and pupae, serum obtained from rabbits hyperimmunized with antigens of mosquito larvae and pupae were used to probe for the mosquito larvae and pupae within the bodies of the backswimmers.…”

“…Serological techniques for studying predator and prey relationships have previously been studied. [1][2][3][4][5][6][7] This paper reports the possibility of using an immunodiffusion technique as a tool for detecting mosquito larval and pupal antigens in the body of potentially predacious animals. The experiment was done using backswimmers, Notonecta sp., a general predator with the larvae and pupae of Aedes aegypti and Culex quinquefasciatus in a predatormosquito model system.…”