On the assessment of prey suitability in aphidophagous Coccinellidae

Abstract

Abstract. Empirical protocols for assessing the suitability of prey for aphidophagous coccinellids are examined and a modified scheme of categorization is presented. It is argued that prey suitability should be assessed independently for larval development and adult reproduction because of potentially divergent nutritional requirements between these life stages. A scheme is proposed for assessing prey suitability for larval development using conspecific eggs as a reference diet against which diets of various prey types can be compared both within and among coccinellid species. Among suitable prey (those that support ca. 100% survival of larvae to the adult stage), those that promote faster development and yield larger adults relative to a conspecific egg diet are considered "optimal" for larvae. Prey that yield viable adults with similar or reduced adult weight after a similar or extended period of development relative to a diet of conspecific eggs are classified as "adequate". Prey are "marginal" if they support the survival of some larvae, but significantly less than 100%. Supplementary water should be provided with any non-aphid diet (e.g. pollen and alternative sources of animal protein) given the potential for food-specific diet-drought stress interactions. For adults, suitable prey are classified as "adequate" if they support the production of viable eggs when fed as a monotypic diet, or "marginal" if they merely prolong adult life relative to a water source. Prey that comprise an optimal or adequate diet for both larval development and adult reproduction are termed "complete" and these can be indexed for relative suitability according to derived estimates of rm. Potential sources of error in diet evaluation studies are identified and discussed.

Weighty matters: Body size, diet and specialization in aphidophagous ladybird beetles (Coleoptera: Coccinellidae)

“…This approach is rooted in studies of the dietary specialization in phytophagous insects, where trade-offs involving the ability to tolerate plant defensive compounds are considered to be important factors in dietary specialization (e.g. Jaenike, 1990;Schoonhoven et al, 1998); it also continues a long tradition of work on prey suitability in ladybirds, which is often still viewed predominantly in terms of prey content, particularly defensive chemicals (Hodek, 1973(Hodek, , 1996Michaud, 2005). There have been three tests of chemistry related trade-offs on different prey (Rana et al, 2002;Ueno, 2003;Fukunaga & Akimoto, 2007), but only one of these has claimed to find any evidence for a chemical trade-off (Rana et al, 2002), and even in this case, the results are open to question (Sloggett, 2008).…”

Slow and fast development in ladybirds: occurrence, effects and significance

“…Semyanov, 2001;Pervez and Omkar, 2004;Nasution, 2007), prey quality (e.g. Kalaskar and Evans, 2001;Omkar and Srivastava, 2003;Kalushkov and Hodek, 2004;Michaud, 2005;Omkar and Mishra, 2005), prey quantity (Omkar and Pervez, 2003;Omkar et al, 2009), photoperiods and wavelengths (Hodek and Ružička, 1979;Hodek and Iperti, 1983;Mishra and Omkar, 2005;Omkar et al, 2005) and sex (Hodek and Hönek, 1996;Dixon, 2000).…”

Prey range of the predatory ladybird Cryptolaemus montrouzieri

“…For instance, prey species that were found to be less suitable for development and reproduction of C. montrouzieri could still be an adequate food source to sustain adult survival (85 % of the adults provided with A. bipunctata eggs was still alive after 65 days). This is probably due to the predator's different nutritional requirements during its larval stages and adult life (Michaud 2005). Besides, our experiments indicate that it is worth investigating a predator's reproductive capacity on a certain candidate prey even when the larvae had difficulty to complete their development on this prey.…”