Chapter 5 Food Relationships Ivo Hodek 1 and Edward W. Evans2 1 Institute of Entomology, Academy of Sciences, CZ 370 05, Cˇ esk é Bud eˇ jovice, Czech Republic 2 Department of Biology, Utah State University, Logan, UT 84322 USA Ecology and Behaviour of the Ladybird Beetles (Coccinellidae), First Edition. Edited by I. Hodek, H.F. van Emden, A. Honeˇk. © 2012 Blackwell Publishing Ltd. Published 2012 by Blackwell Publishing Ltd. 141 5.1 INTRODUCTION balance its nutritional needs (Specty et al. 2003 , Kagata & Katayama 2006 ). Studies of food relations in coccinellids were among The importance of behavioural studies and their the earliest fi elds of research on this family, because of relative shortage in relation to insect predators has the evident interest in ladybirds as natural enemies of recently been stressed (Mills & Kean 2010 ). However, aphid, coccid and mite pests. The history of studies in these studies ( 5.4 ) decisive, qualitative progress has of coccinellid food relations can be divided into been made. Sensory responses, which were previously three periods. In the earliest period, studies focussed questioned, have not only been repetitively docu- on what the ladybirds eat and lists of the prey species mented by many teams in several countries, but also eaten were compiled. In the middle phase, hypotheses the chemical composition of some attracting volatiles and models were constructed that were based on has been revealed; thus the volatiles produced by only fragmentary experiments, usually executed in herbivore - injured plants have been found to attract extremely artifi cial settings. This remained character- enemies to those herbivores. The adaptive phenome- istic well into the end decades of the last century. In non of oviposition deterring substances, left on the agreement with Burk (1988) , the need for empirical substrate by crawling larvae, has been discovered hypothesis testing in future decades was stressed by (Ruzicka 1997 ) and then recorded in a number of coc- Hodek (1996) . cinellid species, and one chemical responsible has Fortunately a new generation of researchers has already been identifi ed (Klewer et al. 2007 ). undertaken more comprehensive causal studies in Under the pressure of the typically discontinuous several branches of coccinellid food research and occurrence of aphid prey, the evolution of coccinellid important progress has been achieved within a rela- feeding behaviour evidently has not led to development tively short period. Here, in the introduction, we briefl y of gustatory discrimination in generalists, at least call attention to some of the studies that are discussed in aphidophagous coccinellids. It has been recorded in this chapter. repeatedly that the ladybirds do not avoid less suitable In 5.2 , Sloggett ’ s (2008b) prey size – density hypoth- or even toxic food. They even do not prefer better food esis, based on concrete observations, opens a new when given a choice (e.g. Nielsen et al. 2002 , Nedv eˇ d dimension of prey specifi city: size relation between the & Salvucci 2008 , Snyder & Clevenger 2004 ; 5.2.1.1 , prey and predator instead of (or together with) physi- 5.2.5 , 5.2.6.1 ). ological suitability and/or chemical composition of the We compile the fi ndings in this chapter in the prey. Body size may be more important than prey optimistic expectation that they represent just the chemistry as a universal factor underlying dietary beginning of a new fruitful period for studies of coc- specialization. cinellid food and feeding. New light has been thrown on nutritional comple- mentarity by Evans and co - authors (Kalaskar & Evans 2001 , Evans et al. 2004 , Evans & Gunther 2005 ) and 5.2 FOOD SPECIFICITY Michaud & Jyoti (2008) , and differences in the larval versus adult food specifi city was stressed by Michaud 5.2.1 Food range (2005) . Some problems of food ecology are being solved by detailed fi eld experiments, often using the Although a tendency to feed on the same or similar addition of artifi cial food and sometimes the mark – prey can be observed in taxonomic groups of coc- recapture techniques (Evans & Toler 2007 , Hon eˇ k cinellids, one may fi nd prey specialists even within et al. 2008a, b , Sloggett 2008a, b , Sloggett et al. 2008 ; individual tribes . Thus, for example, in the generally 5.2.7 ). aphidophagous tribe Coccinellini there are also non - Important recent advances have also been made predaceous species, such as the phytophagous Bulaea concerning patterns and processes of food consump- lichatschovi (Capra 1947 , Dyadechko 1954 , Savoiskaya tion ( 5.3 ). Close study has revealed new insights, for 1966, 1970a ) and the pollinivorous and mycophagous example, as to how prey limitation early in life affects Tytthaspis sedecimpunctata (Dauguet 1949 , Turian ladybird performance later on (Dmitriew & Rowe 1969 , Ricci 1982 , Ricci et al. 1983 ; 5.2.6 ). Within this 2007 ), and how the biochemical properties of prey tribe there are further species which specialize on versus predator may infl uence a ladybird ’ s ability to immature stages of Coleoptera, such as Aiolocaria spp. Food relationships 143 (Iwata 1932, 1965 , Savoiskaya 1970a, 1983 , Kuznet- classifi cation of coccinellids is still partially artifi cial sov 1993 ), Calvia quindecimguttata (Kanervo 1940 ) (Giorgi et al. 2009 ; Chapter 1 ) and thus discussing the and Coccinella hieroglyphica (Hippa et al. 1984 ; food specialization of a whole tribe cannot but have its Table 5.1 ) which feed on pre - imaginal stages of Chry- limitations (Hodek 1996 ). somelidae, or Neocalvia spp. which prey on larvae of Predaceous coccinellids have a wide range of ac - mycophagous coccinellids of the tribe Psylloborini cepted food . Apart from feeding on sternorrhynchan (Camargo 1937 ). Thus, not only entomophagy, but Hemiptera and phytophagous mites, they often prey also also phytophagy and mycophagy are represented on Thysanoptera and young instars of holometabolan within the tribe Coccinellini. Phytophagy is typical for insects (Evans 2009 ) and even food of plant origin the subfamily Epilachninae, mycophagy in the tribe as well as fungi. Taxonomic differences in the rate of Psylloborini (Sutherland & Parrella 2009 ) and feeding coccinellid development are related to the predominant on mites in Stethorini (Biddinger et al. 2009 ). The type of food consumed (Table 5.2 ). Table 5.1 Larval mortality and pupal weight of C occinella hieroglyphica fed on aphids or chrysomelids (Hippa et al. 1984 ) . Larval Fresh weight of Ǩ mortality pupae (mg) Prey % n mean S.E. n Myzus persicae* 20.9 43 9.78 0.13 12 Symydobius oblongus* 22.9 70 9.89 0.12 25 Galerucella sagittariae† —— — —— eggs 67.7 31 10.19 0.72 5 larvae 10.8 74 12.47 0.22 17 *Aphidoidea. †Chrysomelidae. Table 5.2 Rate of natural increase ( rm ) of acariphagous, aphidophagous and coccidophagous coccinellid species (after Roy et al. 2003 ) . Temp rm Species Prey relationship (°C) (d−1) Parastethorus nogripes Acariphagous 25.0 0.152 Stethorus madecassus Acariphagous 25.0 0.155 Stethorus punctum picipes Acariphagous 24.0 0.121 Stethorus pusillus Acariphagous 24.0 0.100 Coccinella septempunctata Aphidophagous 26.0 0.190 Coleomegilla maculata lengi Aphidophagous 25.0 0.110 Olla v -nigrum Aphidophagous 25.7 0.160 Propylea quatuordecimpunctata Aphidophagous 26.0 0.140 Diomus hennesseyi Coccidophagous* 25.0 0.103 Exochomus fl aviventris Coccidophagous* 25.0 0.050 Hyperaspis notata Coccidophagous* 25.0 0.081 Hyperaspis raynevali Coccidophagous* 25.0 0.081 Hyperaspis senegalensis hottentotta Coccidophagous* 26.0 0.070 Rodolia iceryae Coccidophagous* 27.0 0.064 *Coccidophagous ladybirds have characteristically slower development: 5 –10 % per day. 144 I. Hodek and E. W. Evans The great variety of food consumed led to the as - based on examinations of gut contents and fi eld sumption that food specifi city in coccinellids concerns observations. only major taxonomic groupings: e.g. aphidophagous Majerus (1994) gives a useful list of principal and ladybirds only eat aphids. Observed acceptance secondary foods of British coccinellids (although has been mistaken for suitability of prey, even by without defi ning these two categories). Another helpful experienced workers. For example Balduf (1935) food list of Klausnitzer and Klausnitzer (1997) for concluded, on the basis of a survey of accepted food, central European Coccinellidae does not differentiate that no special groups of aphids are selected by lady- the suitabilities of different prey, but just gives exam- birds of the tribes Hippodamiini and Coccinellini. ples of prey consumed by ladybirds based on the Kanervo (1940) treated the six species of aphid prey as authors ’ observations. Species of psyllids and aleyro- a single complex because coccinellids did not show any dids observed to be preyed on by coccinellids have great preference for individual species of aphids. Such recently been listed, while an other compilation in the an assumption has long been perpetuated even though same paper lists essential coccid prey (Hodek & Hon eˇ k contradictory evidence has been reported. This is 2009 ). notably the case in the incorrect characterization of After the invasion of the soybean pest Aphis glycines prey of Adalia bipunctata . Although habitat preference to the USA, Wu et al. (2004) compiled a list of its is important, overgeneralizations may often be errone- natural enemies (including seven coccinellid species) ous. The conclusion that all aphids living on shrubs or in China and southern Korea. Propylea japonica (62%) trees represent suitable prey for A. bipunctata , while and Har. axyridis (10%) were earlier reported as domi- aphids from other habitats are unfavourable prey for nant ladybeetles on A. glycines in China (Wang & Ba this ladybird (Pruszynski & Lipa 1971 ), has already 1998 ). been refuted by earlier data on Aphis sambuci (Hodek 1956 , Blackman 1965 ) as well as by more recent data 5.2.1.1 Methods for d etection of f ood r ange discussed in this chapter. Early studies of predator – prey relationships were The natural food range of coccinellids can be ascert- mostly limited to compiling lists of observed feeding in ained in several ways (Weber & Lundgren 2009 ).