Annals of Warsaw University of Life Sciences – SGGW Animal Science No 52, 2013: 135–139 (Ann. Warsaw Univ. of Life Sci. – SGGW, Anim. Sci. 52, 2013)

The effect of density on the breeding optimization of the tropical house cricket Gryllodes sigillatus (Walker) (Orthoptera: Gryllidae) ANNA MAZURKIEWICZ1, DOROTA TUMIALIS1, ELĩBIETA PEZOWICZ1, JAKUB URBAēSKI2, PAWEà GALEWSKI1, KATARZYNA GÓRAL3 1Department of Animal Environment Biology, Warsaw University of Life Sciences – SGGW 2Department of Genetics and Animal Breeding, Warsaw University of Life Sciences – SGGW 3Insect Factory

Abstract: The effect of density on the breeding an additive to animals’ diet. Moreover, optimization of the tropical house cricket Gryl- insects are more and more often con- lodes sigillatus (Walker) (Orthoptera: Gryllidae). sidered food for humans. This is because The study was aimed at testing the density effect in the tropical house cricket breeding on its sur- of the need to search for new protein vival and growth rate when fed ad libitum. The sources for growing human population tropical house crickets were kept in nine contain- and of a curiosity and desire to learn ers of a volume of 81 litres each. Three experi- new tastes and to break nutritional stere- mental variants were used: 7.5 ml of crickets were otypes. For the second mentioned reason placed in the ¿ rst container, 15 ml in the second and 30 ml in the third. Temperature in contain- the ¿ rst in Poland restaurant “Co To To ers was 29°C, the experiment lasted 25 days. Ob- Je”, that serves exclusively insect dishes, tained results showed that survival did not depend has recently been open in Warsaw. on the initial density in culture containers while Above mentioned circumstances indi- crickets kept at a high density had smaller body cate that the market for food insects has length. The results may affect the optimization of house cricket breeding. a great potential but needs some improve- ment. Insects imported are usually weak Key words: the tropical house cricket, Gryllodes and soon die of exhaustion and conditions sigillatus, survival, population density, growth rate, optimization of breeding of transportation. Country breeding still needs to be developed since its ef¿ ciency may be higher and there is a de¿ cit of in- INTRODUCTION sects from local production. Food insects most often bred include: Terraristics enjoys increasing popularity. crickets, cockroaches, locusts, larvae More and more reptiles and amphibians of wood-eaters, mealworms and wax are kept by both experienced and novice moths. Crickets are bred to the larg- breeders. The animals require mainly est extent. They have low requirements live food. The nutritive requirements of compared with other food insects. The reptiles, amphibians, but also of popular tropical house cricket Gryllodes sigilla- African pigmy hedgehogs Atelerix albi- tus (Walker) has relatively high protein ventris (Wagner, 1841) and many bird content from among bred insect species species, are ful¿ lled by feeding them with (Table 1). insects. They are the main component or 136 A. Mazurkiewicz et al.

The tropical house cricket is the productivity and the quality of animal smallest of bred crickets (18–22 mm products in food invertebrates. of length). It has two transverse black bands on its abdomen and resembles the house cricket. Females are larger than MATERIAL AND METHODS males and wingless. Males have partly reduced wings, hence they contain less Experimental crickets were provided chitin and are more easily digested. The with basic elements of welfare. Having tropical house crickets are distinguished ad libitum access to food and water they by low aggression towards other crick- were free from hunger and thirst. Crickets ets and cannibalism is rare among them. were free from discomfort – their resting Biting animals that feed on them is also area was made of cardboard egg trays rare. The insects are very fast, which is which increased living area and offered an advantage for animals actively hunt- a shelter. The animals were free from ing for their prey. They also show a high pain, injuries, diseases and stress. Stud- fertility and resistance to viruses (like ies were carried out in the food insect e.g. Acheta domesticus Densovirus) and farm “Fabryka owadów” in Warsaw. fungi, which makes them ideal animals Before setting up the experiment, for mass production. The development freshly hatched (maximum 24 h after from hatching till imago lasts 8–15 hatching) cricket larvae were mixed to weeks depending on temperature. obtain uniform sample. The experiment

TABLE 1. Nutritive value of crickets (http://www.livefoodsdirect.co.uk/Category/Banded-Crickets) Speci¿ cation Gryllodes sigillatus Gryllus assimilis Gryllus bimaculatis Energy (kcal/kJ per 100 g) 164/687 130/546 153/640 Protein (%) 21.4 15.2 14.7 Fat (%) 6.9 5.7 8.3 Carbohydrates (%) 4.0 4.5 4.9 Water (%) 66.1 73.3 70.8 Ash (%) 1.6 1.3 1.3

Performed studies had to estimate the lasted 25 days. The initial number of effect of initial density on survival and crickets in 1 ml (mean from three sam- body length in crickets. This information ples) was 424.7. is useful to increase the pro¿ tability of The tropical house crickets were kept breeding. in nine containers of a volume of 81 li- The main aim of performed studies tres each (60×40×34 cm). Temperature was to intensify breeding. This requires, in containers was 29°C. All containers however, providing animal welfare and had the same ventilation and were placed hygienic conditions. Like in farm ani- at the same height on shelves to avoid mals, habitat conditions affect health and differences in temperature between cul- tures. The effect of density on the breeding optimization... 137

Ten pieces of cardboard egg trays calculated by multiplying the ¿ nal vol- glued together were placed in each con- ume of crickets by the number of crick- tainer. They served as the main living ets in 5 ml. Mean body length of crickets area for crickets. was calculated from measurements of 90 There was a small waterer (a bowl randomly selected specimens from each with hydrogel which prevented larvae experimental variant. from drowning) in each container to pro- To calculate the survival of crickets’ vide crickets with permanent free access larvae, their number was counted and to water. Dry food consisted of a mix- calculated per 1 ml before experiment ture of wheat bran and ¿ shmeal (a pro- in the same way as in the end of experi- tein additive that inhibits cannibalism) ment. in the ratio 2 : 1 and trays with carrot – ANOVA, non-parametric Kruskal- a base of diet during the experiment. The -Wallis rank test and non-paramet- access to food and water was provided ric Mann-Whitney U test were used to ad libitum to exclude food as the growth check the statistical signi¿ cance of dif- limiting factor. ferences.

TABLE 2. The relationship between survival and ¿ nal number of crickets and the initial sample volume after 25 days of experiments Variant (initial Standard N Mean Minimum Maximum ȋ2 p volume) deviation emp 7.5 3 27.6000 2.12838 25.30 29.50 Survival 15 3 16.7667 1.70098 15.10 18.50 5.600 0.061 30 3 18.4000 3.96863 15.40 22.90 7.5 3 879.0000 67.10440 806.00 938.00 Final 15 3 1070.0000 109.05503 963.00 1181.00 7.200 0.027 30 3 2343.6667 505.55349 1966.00 2918.00

Three experimental variants were RESULTS AND DISCUSSION used: 7.5 ml of crickets were placed in the ¿ rst container, 15 ml in the second, Performed experiments showed that the and 30 ml in the third. Each variant was initial volume of crickets used in each triplicated. experimental variant did not affect insect On 25th day of experiment crickets survival (p = 0.061) – Table 2. were taken off from culture containers The effect of initial volume of crickets and their volume measured with a cylin- on body length after 25 days of experi- der with millilitre scale. Than two random ment was highly signi¿ cant (p < 0.001). 5 ml samples were taken from each cul- The longest body had the crickets from ture, transferred to containers and photo- experimental variant with the initial vol- graphed. The photos were used to count ume of 7.5 ml, the shortest – those from individuals with the Adobe Photoshop the variant with initial volume of 30 ml software. Final number of crickets was (Table 3). 138 A. Mazurkiewicz et al.

TABLE 3. The relationship between body length and initial volume of the sample after 25 days of experiments Initial Standard N Mean Minimum Maximum Femp p volume deviation 7.5 90 7.2744 0.91216 5.70 10.10 15 90 6.9544 0.95637 5.10 10.00 38.247 <0.001 30 90 6.1344 0.83305 4.50 8.30

Initial volume signi¿ cantly affected kept at 27°C achieved higher survival at the ¿ nal number of crickets in experi- high densities but their growth rate de- mental variants (p = 0.027). The high- clined (Lyimo et al. 1992). est number of insects was obtained In order to obtain the greatest number from culture of initial volume of 30 ml of adult crickets in the shortest possible (Table 2). time one may set up a culture of rela- Many studies (pertaining, however, tively high density but crickets will not mostly to vertebrates) on density-de- achieve as large body size as they would pendent survival indicate that young in- at lower densities. dividuals may die more often at a high density (Sheperd and Cushing 1980, Van der Veer 1986, Myers and Cadigan 1993, REFERENCES Ohman and Hirche 2001, Holbrook and BARNES A.I., SIVA-JOTHY M.T., 2000: Schmitt 2002). In view of the breeding Density-dependent prophylaxis in the ef¿ ciency an important ¿ nding of our mealworm beetle, Tenebrio molitor L. study is that the initial volume does not (Coleoptera: Tenebrionidae): cuticular affect crickets’ survival. One may expect melanization is an indicator of invest- that similar mechanisms were involved ment in immunity. Proc. R. Soc. Lond. here as in mealworms which at high den- B22, 267, 177–182. GIMNIG J.E., OMBOK M., OTIENO S., sities acquired higher resistance to vi- KAUFMAN M.G., VULULE J.M., ruses and fungi (Barnes and Siva-Jothy WALKER E.D., 2002: Density-depen- 2000). Survival of mosquito larvae bred dent development of Anopheles gambiae at medium temperature also increased at (Diptera: Culicidae) larvae in arti¿ cial high densities (Lyimo et al. 1992). Note- habitats. J. Med. Entomol., 39, 162–72. worthy, no symptoms of viral or fungal HAWLEY W.A., 1985: The effect of larval diseases were observed during our ex- density on adult longevity of a mosquito, Aedes sierrensis: epidemiological conse- periments. quences. J. Anim. Ecol. 54, 955–964. Performed studies showed that an in- HOLBROOK S.J., SCHMITT R.J., 2002: crease of density resulted in decreased Competition for shelter space causes body length. Slower growth rate of lar- density-dependent predation mortality in vae and smaller mass of imagines was damsel¿shes. Ecology 83, 2855–2868. noted e.g. in mosquitoes (Gimnig et al. LYIMO E.O., TAKKEN W., KOELLA J.C., 2002). Body mass of female pupae of 1992: Effect of rearing temperature and lar- val density on larval survival, age at pupa- this species was conversely proportional tion and adult size of Anopheles gambiae. to density (Hawley 1985). Mosquitoes Entomol. Exp. Appl. 63, 265–271. The effect of density on the breeding optimization... 139

MYERS R.A., CADIGAN N.G., 1993: Den- dostĊpie do pokarmu ad libitum. ĝwierszcze ba- sity-dependent juvenile mortality in ma- nanowe w czasie eksperymentu byáy hodowane rine demersal ¿ sh. Can. J. Fish. Aquat. áącznie w dziewiĊciu pojemnikach o pojemnoĞci Sci. 50, 1576–1590. 81 l kaĪdy. Zastosowano trzy warianty doĞwiad- OHMAN M.D., HIRCHE H.J., 2001: Densi- czeĔ: w pierwszym pojemniku umieszczono ty-dependent mortality in an oceanic co- 7,5 ml ĞwieĪo wylĊgáych Ğwierszczy, w drugim pepod population. Nature 412, 638–641. 15 ml, a w trzecim 30 ml. KaĪdy wariant do- SHEPERD J.G., CUSHING D.H., 1980: Ğwiadczenia powtórzono trzykrotnie. Temperatu- A mechanism for density-dependent ra w pomieszczeniu wynosiáa 29°C. Eksperyment survival of larval ¿sh as the basis for trwaá 25 dni. W wyniku przeprowadzonych badaĔ stwierdzono, Īe objĊtoĞü początkowa Ğwiersz- a stock-recruitment relationship. J. Cons. czy uĪytych w kaĪdym wariancie doĞwiadczenia Int. Explor. Mer. 39, 160–67. nie wpáywa na przeĪywalnoĞü owadów, jednak Van Der VEER H.W., 1986: Immigration, Ğwierszcze hodowane w wiĊkszym zagĊszczeniu settlement, and density-dependent mor- miaáy mniejszą dáugoĞü ciaáa. Uzyskane wyniki tality of a larval and early postlarval mogą przyczyniü siĊ do zoptymalizowania ho- 0-group plaice (Pleuronectes platessa) dowli tego gatunku Ğwierszcza. population in the western Wadden Sea. Mar. Ecol. Prog. Ser. 29, 223–236. http://www.livefoodsdirect.co.uk/Category/ MS. received in November 2013 Banded-Crickets Authors’ address: Streszczenie: Wpáyw zagĊszczenia na optymali- Anna Mazurkiewicz zacjĊ hodowli Ğwierszcza bananowego Gryllodes Wydziaá Nauk o ZwierzĊtach SGGW sigillatus (Walker) (Orthoptera: Gryllidae). Praca Katedra Biologii ĝrodowiska Zwierząt miaáa na celu zbadanie wpáywu zagĊszczenia po- ul. Ciszewskiego 8, 02-786 Warszawa czątkowego w hodowli Ğwierszczy bananowych Poland na ich przeĪywalnoĞü oraz szybkoĞü wzrostu przy e-mail: [email protected]