An Investigation Into the Chemical
Composition of Alternative
Invertebrate Prey
D.G.A.B. Oonincx1 and E.S. Dierenfeld2
1Wageningen Institute of Animal Sciences, Animal Nutrition Group, Wageningen
University, Wageningen, The Netherlands
2Department of Animal Health and Nutrition, Saint Louis Zoo, St. Louis, Missouri
The aim of this study was to determine the chemical composition of eight
invertebrate species and evaluate their suitability as alternative prey. The species selected were rusty red ****roaches (Blatta lateralis), six-spotted ****roaches (Eublaberus distanti), Madagascar hissing ****roaches (Gromphadorhina portentosa), fruit flies (Drosophila melanogaster), false katydids (Microcentrum rhombifolium), beetles of the mealworm (Tenebrio molitor), and superworm beetles (Zophobas morio), as well as woodlice (Porcellio scaber).
Dry matter (DM), crude protein, crude fat, neutral detergent fiber, acid detergent fiber, ash, macro and trace minerals, vitamins A and E, and carotenoid concentrations were quantified. Significant differences were found between species. Crude protein content ranged from 38 to 76% DM, fat from14 to 54% DM, and ash from 2 to 8% DM. In most species, calciumhosphorus was low (0.08–0.30:1); however, P. scaber was an exception (12:1) and might prove useful as a dietary source of calcium for insectivores. Vitamin E content was low for most species (6–16 mg/kg
DM), except for D. melanogaster and M. rhombifolium (112 and 110 mg/kg DM). The retinol content, as a measure of vitamin A activity, was low in all specimens, but varied greatly among samples (0.670–886 mg/kg DM). The data presented can be used to alter diets to better suit the estimated requirements of insectivores in captivity. Future research on the topic of composition of invertebrate prey species should focus on determination of nutrient differences owing to species, developmental stage, and diet.
INTRODUCTION
In most zoos and private collections, only a limited selection of invertebrates is offered as feeder animals. This selection often depends on the availability and acceptance by the predator. However, other factors should also be taken into account when formulating an optimal diet, such as natural feeding ecology, dietary requirements of the predator, and the chemical composition and potential digestibility of the prey offered. For the commonly fed invertebrates, information on chemical composition is available [Barker et al., 1998; Bernard and Allen, 1997; Finke, 2002; Jansen and Nijboer, 2003; Oonincx et al., 2010]. Although readily available, these species may not be the most suitable prey for insectivorous species to meet optimal nutritional demands or fulfill behavioral needs. The aim of this study was to determine the chemical composition of a selection of alternative invertebrate species that may be used to complement or improve the diet for insectivorous animals in zoos and private collections.
MATERIALS AND METHODS
Animals
Seven species of potential feeder insects and one species of crustacean were
examined in this investigation. Because earlier studies on insects have shown diet to be a major determinant influencing their chemical composition [Oonincx and van der Poel, 2010; Ramos-Elorduy et al., 2002; Simpson and Raubenheimer, 2001], information on the provided diet is detailed where available.
Rusty red ****roaches (Blatta lateralis: Dictyoptera; Blattidae) of two sizes,
small (second instar nymphs; 0.9–1.3 cm) and medium (third instar nymphs;
1.3–1.9 cm), were provided by a commercial supplier (TheBugpros.com). They were offered a small amount of water upon arrival and sampled within 24 hr of receipt via overnight shipment.
Six-spotted ****roaches (Eublaberus distanti: Dictyoptera; Blaberidae) of three sizes, small (1.5–3.0 cm), large (4.5–5.0 cm), and adult nymphs (4.5–5.0 cm), were provided by Agama International (Montevallo, AL). Upon arrival, they were housed on a substrate of woodland soil and provided with apple and dog food (Purina HiPro, Nestle´ Purina PetCare Company, St. Louis, MO) and sampled within 24 hr of receipt via overnight shipment.
Madagascar hissing ****roaches (Gromphadorhina portentosa: Dictyoptera;
Blattidae) of two sizes, small (1.5–3.5 cm) and adult (4.0–6.0 cm), were reared at the St. Louis Zoo on a diet of laboratory rodent biscuit (Rodent Block, Purina Mills, St. Louis, MO) and dry dog food (Purina HiPro), supplemented with lettuce, apples, and sweet potatoes. Animals were sampled immediately after removal from their enclosure.
Fruit flies (Drosophila melanogaster: Diptera; Drosophilidae) were purchased
from Carolina Biological Supplies (Burlington, NC) and reared for two generations on Formula 424 (Carolina Biological Supplies). Adult D. melanogaster were chilled in their rearing containers at 71C for approximately 15 min and sampled immediately after removal from their enclosure.
False katydids (Microcentrum rhombifolium: Orthoptera; Tettigoniidae) were
provided by the St. Louis Zoo Insectarium where they were reared on a diet of firethorn (Pyracantha spp.), supplemented with raspberries, blackberries (Rubus spp.), and lettuce (Lactuca spp.) leaves. Only adults were sampled, immediately after removal from their enclosure.
Common rough woodlice (Porcellio scaber: Isopoda; Porcellionidae) were
provided by the St. Louis Zoo’s Insectarium and reared at the Orthwein Animal Nutrition Center (OANC) at the zoo for 6 weeks. They were housed in plastic bins on a substrate of wood chip mulch, leaf litter, and well-rotted wood, and supplemented with sweet potato, carrot, and apple. Only adults were sampled, immediately after removal from their enclosure.
Mealworm beetles (Tenebrio molitor: Coleoptera; Tenebrionidae) were provided by Timberline Fisheries (Marion, IL). Upon arrival, they were housed on a substrate of wheat bran, as provided by the supplier, and a fresh slice of potato was provided for moisture; beetles were sampled within 24 hr of arrival.
Superworm beetles (Zophobas morio: Coleoptera; Tenebrionidae) were provided by the same supplier, and housed and sampled identically as described above for mealworm beetles.
Laboratory Analyses
For all species except woodlice (quantity insufficient), fresh tissues (n51–5
samples) were homogenized in a food processor and subsamples (0.5 g, in duplicate) were taken for vitamin A, E, and carotenoid extraction, according to Barker et al. [1998]. After evaporation under N2 gas, extracts were sealed in cryovials and stored at 201C until shipped overnight to Arizona State University for HPLC analysis [McGraw et al., 2006]. Dry matter (DM) content of remaining tissues was determined via freeze drying at the OANC Nutrition Laboratory until a stable weight was reached. Dried samples were ground in a laboratory mill and sent to Dairy One Forage Laboratory (Ithaca, NY) for proximate (crude protein, crude fat, detergent fiber fractions, ash) and macro (calcium (Ca), phosphorus (P), magnesium (Mg), potassium (K), and sodium (Na)) and trace mineral (iron (Fe), zinc (Zn), copper (Cu), manganese (Mn), and molybdenum (Mo)) determinations. Invertebrates were pooled to provide a minimum of 10 g DM per sample for each set of analyses.
Proximate and mineral assay data, except for the M. rhombifolium and
woodlice (n51), were analyzed by MANOVA using SPSS version 15.0 to determine whether species effects on composition were present. Within the ****roaches, a MANOVA was used to determine the effect of developmental stage. For specific differences, the data were analyzed by analyses of variance (ANOVA) followed by a Tukey’s Honestly Significant Difference test. Differences between mean values were considered significant at ar0.05.
RESULTS
Average values of proximate, mineral, and vitamin analyses are presented in Tables 1–3, respectively. Where applicable, standard deviations and the stage of development are shown. The MANOVA indicated that species had a significant effect (Pillai’s trace F59.424, Po0.001) on all analyzed nutrients, except for Mo. ****roaches
The three ****roach species differed distinctively in chemical composition.
Six-spotted roaches contained the highest DM content ( 40–50%) of the three species. Stage of development significantly affected most nutrients (Pillai’s trace F55.129, P50.007), as well as DM content, with the exception of Fe, Mo, and S. All roaches contained high concentrations of crude protein (38–76% DM basis; Table 1), similar to values found in literature on American ****roaches (Periplaneta americana; 54% DM) [Bernard and Allen, 1997].
****roaches contained moderate-to-high concentrations of crude fat. In the
earlier stages of development (small vs. large or adult stages), they contained more protein and less fat than larger specimens of the same species, as is true for most animals (a notable exception being neonatal rodents). Crude fat percentage increased with age in B. lateralis (from 14 to 27% DM) and G. portentosa (from 20 to 25% DM), but that same pattern was not present in E. distanti. The reported fat content of American ****roaches (28.4%) was slightly higher than the first two species, but lower than E. distanti [31–54% DM; Bernard and Allen, 1997].
In terms of dietary ‘‘fiber’’ content, both neutral detergent fiber (NDF) and acid detergent fiber (ADF) content were similar for B. lateralis, averaging about 12% of DM. Approximately 60–90% of ADF in insects is chitin provided by the exoskeleton [Barker et al., 1998; Finke, 2007; Oyarzun et al., 1996]. The ADF content of G. portentosa was 10–13% of DM. However, NDF in this species was considerably higher ( 36% of DM) and may represent true dietary fiber from vegetables in the digestive tract.
Both body and gut content, especially in species with a relatively large gut or consuming high fiber diets, contribute to the nutrient content of feeder prey species. Thus, diet may provide essential nutrients otherwise unavailable from the insect with an empty gut [Finke, 2003; Klasing et al., 2000].
Total ash content of E. distanti was significantly lower (2–4% DM) than in B. lateralis (7–8% DM; Po0.001)) and G. portentosa (4–8% DM; P50.007), similar to American ****roaches [3.3% DM; Bernard and Allen, 1997]. Mineral content among the three ****roach species differed greatly (Table 2). As expected [Barker et al., 1998; Finke, 2002; Studier and Sevick, 1992], an inverse Ca

ratio was found in ****roaches. Therefore, if using ****roaches as a feeder species, Ca supplementation is necessary to achieve a Ca

of 1:1 [Donoghue and Langenberg, 1994]. Larger invertebrates (adult or large nymphs) contained lower concentrations of most minerals (Ca, P, Mg, K, Na, Zn, Cu, Mn, and Mo) compared with smaller sized individuals of the same species. Nonetheless, roaches seem to be an excellent dietary source of Zn and Cu. Fe content in E. distanti and G. portentosa increased with age. Because excess dietary Fe can contribute to Fe storage diseases in several species of birds and mammals [Bonar et al., 2006; Farina et al., 2005; Sheppard and Dierenfeld, 2002; Williams et al., 2008], it is important to know all contributory factors for Fe intake.
Vitamin E content of ****roaches was relatively low (11–16mg/kg DM; Table 3), providing approximately 20IU vitamin E/kg DM (1mg51.49IU). Pennino et al. [1991] found almost 10-fold higher concentrations of vitamin E (179 IU/kg DM) in wild-caught ****roaches. Retinol content varied from 25 to 116mg/kg DM; therefore, calculated vitamin A activity (0.3 mg retinol51 IU) was low (o400 IU/kg DM) compared with estimated requirements, using domestic felids as a carnivore model for insectivores ( 5,000 IU/kg DM maintenance; 9,000 IU vitamin A/kg DM, growth, and reproduction; [NRC, 2006].
As with vitamin E, free-ranging ****roaches reported by Pennino et al. [1991] contained considerably more vitamin A (1,000 IU/kg DM) than the ****roaches in this study. Lutein, zeaxanthin, and b-carotene was found in all samples. Although dehydrolutein (DHL) and anhydrolutein (AHL) are metabolites of lutein, DHL was not quantifiable in B. lateralis or E. distanti, and AHL was only found in E. distanti samples. Both b-carotene (Bcar), found in all three ****roach species, and b-cryptoxanthin (Bcry) have provitamin A activity in many species [McGraw et al., 2006]. Owing to the widely varying molecular structures of carotenoids, there might be species-dependant differences in the ability of vitamin A synthesis from these compounds. Because vitamin A deficiency has been reported for insectivores fed unsupplemented invertebrates [Ferguson et al., 1996], vitamin A metabolism could be explored among different ****roach species fed identical diets to evaluate synthetic pathways, and determine optimal dietary regimens/ingredients for production of feeder insects with the most appropriate vitamin A levels.
Compared with mealworm and superworm larvae, rusty red roaches (B. lateralis) and hissing ****roaches (G. portentosa) provide high protein, lower fat alternative food items for insectivores—more similar to cricket proximate nutrient composition [Barker et al., 1998; Bernard and Allen, 1997; Finke, 2002; Jansen and Nijboer, 2003; Oonincx et al., 2010; Pennino et al., 1991].
Six-spotted ****roach nymphs (E. distanti), on the other hand, tended to be higher in fat and may be a poorer source of protein than either the other roach species, crickets, or beetle larvae. Owing to their high fat content, they may be considered a high-calorie treat item or could prove useful for improving body condition of insectivores. Mineral content of roaches was variable, depending on species, size, and diet, but all roaches examined still contained inverse Ca

ratios, in the same ranges as the more commonly fed invertebrate prey [Barker et al., 1998; Bernard and Allen, 1997; Finke, 2002; Jansen and Nijboer, 2003; Oonincx et al., 2010]. Other macrominerals were found in concentrations that would be considered adequate to meet known nutritional requirements of domestic felids [NRC, 2006], considered to be the most suitable physiologic model for insectivores. Conversely, some microminerals, particularly Fe, could be excessive. Small hissing
****roaches are similar in body size to adult house crickets, and may provide a suitable nutritional substitute for crickets in insectivore diets (if consumed by the insectivore).
Published online in Wiley Online Library (wileyonlinelibrary.com).
DOI 10.1002/zoo.20382
Received 31 July 2009; Revised 24 December 2010; Accepted 7 January 2011
The current address of D.G.A.B. Oonincx is Laboratory of Entomology, Department of Plant Sciences,
Wageningen University, PO Box 8031, 6700 EH Wageningen, The Netherlands.
The current address of E.S. Dierenfeld is Novus International, Inc., 20 Research Drive, St. Charles,
MO 63304.
Correspondence to: D.G.A.B. Oonincx, Laboratory of Entomology, Department of Plant Sciences,
Wageningen University, PO Box 8031, 6700 EH Wageningen, The Netherlands.
E-mail:
dennisoonincx@hotmail.com
r 2011 Wiley-Liss, Inc.
Zoo Biol 29:1–15, 2011. c 2011 Wiley-Liss, Inc.
Keywords: chemical composition; insect; invertebrate; insectivory