Effects of alternative food on cannibalism and herbivore suppression by carabid larvae

Abstract

1. Predator and alternative food density are important factors influencing herbivore suppression by generalist predators. Herbivore suppression can be reduced if predators forage preferentially on alternative foods. Cannibalism can increase at high predator densities, further reducing herbivore suppression. However, complex interactions are possible, as alternative food can increase predator abundance and survival restoring top-down effects on herbivores.2. In two species of carabid larvae (Poecilus chalcites and Anisodactylus ovularis), we studied how alternative foods (fly pupae and grass seeds) and predator density affect predation of black cutworm larvae and how alternative foods affect cannibalism among carabid larvae.3. Adding alternative food to microcosms generally reduced total predation of cutworms. However, the strength of this effect was dependent on carabid species, larval density, and food type.4. Increasing larval density from one to three per microcosm reduced per-capita predation by both species irrespective of alternative food treatment.5. Alternative food reduced cannibalism in both carabid species and increased survival of carabid larvae in field plots, such that twice as many were captured in plots subsidised with pupae than plots with no alternative food.6. These results provide new insight into the complex interactions that influence predator survival and herbivore suppression in resource diverse habitats by demonstrating the primacy of intraguild interactions among carabid larvae.

Factors that influence the level of weed seed predation: A review

“…Besides, seasonal population fluctuations (Honek et al 2006), phenological changes in predators life cycle (e.g., overwintering stages, breeding season, dispersal etc. ), biotic factors such as high-level trophic interactions (Davis & Raghu 2010), the presence of alternative food sources (Frank et al 2010(Frank et al , 2011, abiotic factors such as temperature , seed distribution patterns on the soil surface (Noroozi et al 2012), and the method of seed exposure in the field (Shuler et al 2008;Saska et al 2014) can be attributed to levels of weed seed predation in the field.…”

Impact of predatory carabids on below- and above-ground pests and yield in strawberry

“…It is also possible that the sentinel weed seeds in our field trials during August and September may have reduced predation in our other trials with belowground O. sulcatus larvae. Other carabid species have been shown to feed less on insect prey when grass seeds are present (Frank et al 2010(Frank et al , 2011.…”

“…9 week 9 year F 2,519 = 9.3, P \ 0.001 year F 2,75 = 6.9, P = 0.002, week 9 year F 1,75 = 3.9, P = 0.053, treat. 9 week 9 year F 2,75 = 2.7, P = 0.076 (Thomas et al 2009;Frank et al 2010). In our study, few carabid larvae were collected from soil samples or in pitfall traps to study their potential impact.…”

Arthropod carrion influences plant choice, oviposition, and cannibalism by a specialist predator on a sticky plant

“…Cannibalism is pervasive amongst arthropods, including carnivorous (Elgar, 1992) and non-carnivorous taxa (Richardson et al, 2010), and it can be the result of a variety of density-dependent and independent factors (Fox, 1975;Polis, 1981;Richardson et al, 2010). Cannibalism by natural enemies may be increased when prey abundance is reduced or low in quality (Hironori & Katsuhiro, 1997;Snyder et al, 2000;Denno et al, 2004;Moreno-Ripoll et al, 2012) and is ameliorated by alternative foods, including PPFs (Cottrell & Yeargan, 1998;Leon-Beck & Coll, 2007;Frank et al, 2010). Arthropod carrion had mixed effects on egg cannibalism by J. wickhami: at low adult densities, egg cannibalism was infrequent and did not decrease when carrion was present.…”

“…By providing food resources, plants may satiate natural enemies and decrease consumption of herbivores (Cottrell & Yeargan, 1998;Stenberg et al, 2011). Alternatively, satiation may reduce cannibalism (Leon-Beck & Coll, 2007;Frank et al, 2010), an important factor contributing to natural enemy population dynamics (Fox, 1975;Polis et al, 1989). Whether arthropod carrion, entrapped on plants, functions similarly to any of the previously mentioned mechanisms is unknown; thus far authors have postulated that carrion either attracts or retains predators on the plants (Krimmel & Pearse, 2013;LoPresti et al, 2015).…”