Assimilation of carbon and nitrogen from pollen and nectar by a predaceous larva and its effects on growth and development

Abstract

Abstract. 1. Predaceous insects may benefit from feeding on non‐prey foods, such as pollen, nectar, and honeydew, because they can provide nutrients that help maintain metabolism and enhance overall nutrient intake. Yet, the extent to which predaceous insects can assimilate non‐prey food and the importance of diet mixing during particular life history stages is poorly understood. In this study the relative contribution of an omnivorous diet to the growth and survivorship of a predaceous larva was tested in a hypothetical situation in which nutritionally optimal prey was not available. The study system comprised a predaceous larva (second‐ and third‐instar larvae of the green lacewing Chrysoperla carnea), nutritionally poor prey (larvae of Drosophila melanogaster), and non‐prey food (pollen suspension, a mixture of bee pollen and artificial nectar (1 M sucrose solution)). Chrysoperla carnea larvae in the mixed diet treatment were provided with both Drosophila larvae and pollen suspension, while those reared on the prey and non‐prey diet treatments received only Drosophila larvae or pollen suspension respectively. 2. The inclusion of pollen and sucrose in their diet enhanced the growth of C. carnea larvae. Second instars reared on the mixed diet developed significantly faster than their cohorts reared on the prey diet, however third instars reared on the mixed diet did not develop faster than their cohorts reared on the prey diet. Larvae reared on the mixed diet became larger adults than did those reared on either the prey or non‐prey diets. Third instars reared on the non‐prey diet completed their development while second instars in the non‐prey diet treatment failed to pupate. 3. Stable isotope analysis indicated that the larvae obtained most of their carbon (55–73%) and nitrogen (71–73%) from Drosophila but acquired only a minor amount of carbon (2–5%) and nitrogen (3–11%) from pollen. Larvae reared on the mixed and non‐prey diets acquired a relatively significant amount of carbon (23–51%) from sucrose. 4. A model, which included a novel fractionation factor to account for the isotopic effect of metamorphosis, was developed to explain the proportion of larval growth attributable to each diet item. It explained the adult δ13C values to within 0.2‰ and adult δ15N values to within 0.7‰ in all treatments. 5. Adults fed 15N‐labelled pollen as larvae retained the 15N signal of the pollen as adults. 6. The collective results of this study support the view that, despite their dependence on prey arthropods to obtain most of their dietary nitrogen, omnivorous lacewing larvae can enhance their growth and development by supplementing their diets with alternative non‐prey food resources. This finding is consistent with the notion that omnivory has evolved as a feeding strategy to acquire both additional nitrogen as well as trace nutrients.

Suitability of leguminous cover crop pollens as food source for the green lacewing Chrysoperla externa (Hagen) (Neuroptera: Chrysopidae)

“…Moreover, the authors found a large proportion of unaltered starch in C. carnea feces. Alternatively, as pointed out by Patt et al (2003), apart from the nutritional value of macro-nutrients found in pollen, vitamins, mineral nutrients and sterols are important for digestion and other metabolic processes (Stanley & Linskens 1974, Waldbauer & Friedman 1991. Thus, differences in the digestibility and assimilation of nutrients from different pollen species are expected to have influence on predator fecundity.…”

“…The nutritional value of such food varies with predator species and circumstances in which they find themselves. For some predaceous species non-prey items are essential during a non carnivorous life stage (Principi & Carnard 1984, Hickman & Wratten 1997, and for others plant-food may act as a supplement until nutritional optimal prey is located or as a complement of a suboptimal prey (Eubanks & Denno 1999, Evans et al 1999, Beckman & Hurd 2003, Patt et al 2003. Green lacewings are polyphagous predators whose larvae are carnivorous and adults have varied feeding habits with species being either carnivorous or glyciphagous and polliniphagous (Principi & Carnard 1984).…”

Los crisópidos de la Península Ibérica y Baleares (Insecta, Neuropterida, Neuroptera: Chrysopidae)

“…63,64), siendo, especialmente en estos estadios larvario, excelentes aliados contra estos fitófa-gos (New, 1988b;McEwen et al, 2001;Miller et al, 2004), y a veces son muy selectivas, elemento que contribuye a la citada especificidad de sustrato sobre los que a veces hallamos los imagos de algunas especies. A veces son predadoras de huevos de otras especies de crisopas o de otros insectos (Canard, 1970bCarvalho et al, 1998), y complementan su dieta con levaduras, polen y néctar (Hagen & Tassan, 1970;Patt et al, 2003), y en más de una ocasión (y no es broma) el autor ha observado alguna "osada larva antropófaga" introduciéndome sus mandíbulas por algún pliegue de mi piel con la "maliciosa" intención de obtener de mí algún fluido como alimento.…”

15N/14N ratios of amino acids as a tool for studying terrestrial food webs: a case study of terrestrial insects (bees, wasps, and hornets)

“…Little information is available regarding isotopic and trophic changes associated with metamorphosis, from feeding during the larval and adult stages through starvation during the chrysalis stage. Also, pollen and nectar are basal resources in terrestrial food webs (e.g., Memmott 1999;O'Reilly et al 2002, Patt et al 2003, and feeding on pollen and nectar by pollinators is important for maintaining plantpollinator interactions and terrestrial food webs (Memmott 1999). However, investigations of feeding on pollen and nectar would be difficult using only bulk d 15 N values (Patt et al 2003), because large variations exist among the d 15 N values of these foods.…”