Ecolocv eNo Bnnevron

Model for Use in Mass-Production of Acheta domesticus(Orthoptera: Gryllidae) as Food

MEGHA N. PARAJULEE, GENE R. DTFOLIART, ENO DAVID B. HOGG

Department of Entomology, University of Wisconsin,Madison, WI 53706

ABSTRAcT e p,od,,"uJ,, EiSt"iilx"i;'"'Jil;L1itl111l]3?11.,

.n" harvest or a qrede-termined numbei of eggs of house cricket, Acheta domesticus (L.), per day by regulatingthe numbers and ages of adults in the breeding colony. With a discard age of 24 d, theproduction model predicted a sustainable harvest of -4,000 (4,440) and 6,000 (6,660)

crickets per day when four or six pairs, respectively, of newly emerged adults were addedper day to an initial breeding colony of 50 pairs. Natality was,based on the number ofnymphs surviving to 7 d per surviving female, after which little nymphal mortality oc-curted. Orripositional surface area availability was not a limiting factor in egg production.

KEY WORDS Acheta domesticus, human food, mass-production

Tnn nousr cRICKET, Acheta domesticus (L.), isa cosmopolitan, omnivorous insect that is easilyreared under conffned conditions (Patton 1978).Previous research (Jordan & Baker 1956; Patton1963, 1967; Polt l97l; Clifford et al. 1977; Mc-Farlane 1985; Parajulee & DeFoliart 1993) de-scribed the rearing methods and emphasized thewidespread use and suitability of house cricketsfor laboratory studies. In the United States andCanada it is widely used as ffsh bait and formaintaining insectivorous vertebrates in captiv-ity. Finke et al. (1989) found that the housecricket is of high protein quality and slightlysuperior to soy protein at all levels of feedingwhen fed to weanling rats, and Nakagaki et al.(1987) found that dried house crickets are asource ofhigh quality protein for broiler chicks.The cricket is recommended by Taylor & Carter(1976) as an ingredient in gourmet recipes. Na-kagaki & DeFoliart (1991) have shown thecricket to be competitive compared with otherlivestock on the basis of food conversion effi-ciency. Because of its palatability, protein qual-ity, and high food conversion efficiency, thecricket is a promising candidate for wider promo-tion as food and animal feed (DeFoliart 1989).

We designed a mass-rearing system which in-volves a breeding colony and 32 rearing units,each unit providing enough space (50 by 44by20.5 cm) to rear =6,000 crickets to harvestablesize (eighth instar). One cage is seeded each daywith enough eggs to allow for mortality, and the6,000-cricket cohort is harvested 32 d later. Fol-lowing harvest, each cage is reseeded (one cageper day) with 9-d-old eggs (ready to hatch) fromthe breeding colony. Thus, 6,000 crickets per day

are harvested on a continuing basis. The systemis expandable depending upon the daily produc-tion desired.

Previously, it has been difficult to determineproper number of eggs to seed per cage withoutsorting and counting thousands of eggs from theoviposition medium.each day. The two objec-tives of our study were to (1) develop and test aproduction model based on age-specific natalityand cumulative net maternity of crickets thatwould accurately predict the number and ages ofcrickets needed in the breeding colony to pro-duce the desired number ofeggs per day, and (2)to determine whether the area of ovipositionalsurface available was limiting to daily egg pro-duction.

Materials and Methods

Developing the Production Model. To deter-mine cricket natality and cumulative net ma-ternity, we used net reproductive rate (Rn) as

defined as2,l,m, (Andrewartha & Birch 1954),where survivorship (1") is the probability of anindividual female attaining age r (days) and na-tality (m,) is the number of female nymphs pro-duced by a female between ages r-l and r. Wedefine cumulative net maternity as 2(Ro) to in-clude male offspring.

Three simultaneous replicates of 50 pairs ofnewly emerged adult crickets were confined inglass terraria (50 bv 30 by 26 cm) covered with aperforated aluminium lid to prevent cricketsfrom escaping. We started the experiments with50 pairs because ofaberrations in cricket behav-ior at low population densities (McFarlane

0022-0493 193 I 1 424 -1428$02.00 l0 O I 993 Entomolo gical S ociety of America

October 1993 Penelur,rn ET AL.: PnooucrloN Monnr, ronAcheta domesticus t425

1962). The crickets were fed the Animal Nutri-tion Research Council Reference Chick diet (Na-tional Research Council 1977) for broiler-typechicks, modified by the addition of 0.5% NaCland 3Vo fish protein (McFarlane 1964). Observa-tions were made daily to determine survival offemales and to remove dead crickets. Feed andwater were provided ad libitum. The feed wasprovided in a petri dish at one end ofthe terrar-ium. Fresh tap water was supplied to the breed-ing colony using a standard chick watering de-vice consisting of a 0.9-liter glass jar with ascrew-on plastic pan base. Aluminum screeningunder the water outlet prevented the cricketsfrom crawling into the opening and drowning.The water bottles were emptied, washed, andrefilled every 3 d to prevent crickets from drink-ing fouled water. Three pieces of cardboardchicken egg cartons (30 by f5 cm) were placed ineach terrarium to provide resting and hiding sur-faces for the crickets.

Petri dishes (15 cm diameter) were used as eggtrays and filled with moistened peat moss as anovipositional substrate. For 45 d, individual eggtrays were exposed to the crickets for 24 h-peri-ods, allowing for oviposition. The trays werethen removed, covered with a lid, and incubatedat 34 -r 2"C (Roe et al. 1980). Just before egghatch, the trays were placed in vented plasticstorage boxes (34 by 2I by 9 cm) to rear thenymphs. Condensed water on the undersurfaceof the lid was removed by paper towels to pre-vent drowning of newly eclosed nymphs. Afterthe eggs hatched (incubation period of 9 d at34 -r 2'C), the lid was removed from the egg trayand food and water were provided for the newlyeclosed nymphs. A cotton dental wick (I by 5 cm)was inserted into a vial containing water and laidon its side on the storage box floor to providewater for the nymphs. One or two folded papertowels were provided in each storage box to in-crease surface area and facilitate cricket molting.Finely ground feed was sprinkled over the papertowels. Nymphs were reared for 7 d, then killedby freezing and counted. Patton (1978) deter-mined that at 32 I l"C, A. domesticus moltsoccur at :3-d intervals, thus at34 -+ 2'C, most ofour nymphs were in the third instar when killedfor counting. Clifford et al. (1977) found that mostA. domesticas mortality occurs in the first andsecond instars with essentially l00Vo survivalthereafter; thus, the number of crickets survivingto 7 d should closely approximate the total num-ber of crickets surviving to harvest. Our fecun-dity model, then, is based on the number ofnymphs surviving to the seventh day.

The life-history statistics, such as net repro-ductive rate and cumulative net maternity, werecalculated from the age-speciffc life-table analy-sis. These life-history statistics were then used toexamine the dynamics of production for the ad-dition of either 4 or 6 pairs of newly emerged

adults per day in an initial breeding colony of50pairs.

Testing the Production Model. The initialbreeding colony consisted of 50 pairs of newlyemerged adult crickets conffned in an aluminumcage (50 by 44by 20.5 cm), to which four pairs ofnewly emerged adults were added daily (herein-after referred to as a four-pair colony). Petridishes (I5 cm diameter) were used as egg traysand moistened peat moss was provided as anovipositional substrate as described above. For50 d, individual egg trays were exposed to thebreeding colony for a 24-h period, allowing foroviposition, then removed and incubated at 34 -r2oC under continuous light. The egg trays wereplaced in vented storage boxes and nymphs werereared, killed, and counted as described previ-ously.

In a second experiment under the conditionsand procedures just described, six pairs of newlyemerged adults were added daily to an initialbreeding colony of 50 pairs (hereafter referred toas a six-pair colony). Eggs were harvested andnymphs reared for 7 d, then killed by freezingand counted as before.

In both experiments, older adults were not re-moved from the breeding colony, but dead adultswere removed when found.

Oviposition Substrate Area as a Limiting Fac-tor. This experiment was conducted as describedfor the four-pair colony, except that the oviposi-tional surface area was reduced by 50Vo. A semi-circular wooden block of 5 cm thickness, -2times the height of the petri dish rim, was ffttedagainst the lS-cm-diameter petri dish to providea barrier against oviposition in that half of thepetri dish. The other half was filled with moist-ened peat moss. Eggs were harvested after ex-posing the modified egg trays to the breedingcolony for a24-h period for 46 consecutive days.Egg trays were incubated and the nymphs werereared for 7 d before freezing and counting as

before. The mean production from this experi-ment was compared with that of the productionachieved from the four-pair colony experimentby using t test statistics.

Results and Discussion

Developing and Testing the ProductionModel. Fig. I shows the age-specific natality(mean number of offspring surviving for 7 d persurviving female) for the cricket cohorts. A peakof 90 offspring per female occurred on day ll,which repres ents 6.4Vo of cumulative net mater-nity, and declined to fewer than 3 offspring perfemale by day 45 (Fie. l). No adult mortality wasrecorded before age 24 d, and survivorship de-clined to TIVo by the termination of the experi-ment on day 45 (Fig. 2). Although the survivor-ship seems apparently high even on day 45(70Vo), reduced competitive ability of older fe-

L426

FEMALE AGE (DAYS)

Fig. 1. Number of A. domesticus offspring (surviv-ing for 7 d) produced per adult female per day at 34 +2'C. Each data point represents the mean of three co-horts.

males contributes to very little effect on overallpopulation growth (see below for the concept ofdiscard age and the poor competitive ability ofthe older females). The mean cumulative net ma-ternity for the generation (twice R") was 1,407.

Using the natality (Fig. 1) and survivorship(Fig. 2) data from the single-aged cricket cohorts,we developed a model to predict the harvest fora mass-rearing production system:

Et+t:2(uuwt.)i

No,t = P

Nr,r: sr - rNl - j,t - l,i>O

where E represents the number of eggs, N is thenumber of adult females, i is adult age class, f istime, b is natality (male plus female offspring),p is the number of cricket pairs added daily, ands is survivorship. A production colony differs

1.00

0.90

0.80

0.70

0.600 '1 0 20 30 40 50

FEMALE AGE (DAYS)

Fig. 2, Survivorship of female A. domesticus adrltsat34 ! 2'C.

JounNer- or EcoNol,rrc ENToMoLocy Vol. 86, no. 5

100

80

60

A

-.- obssrued

-

Predicted

B

+ Observed

-

Predicted

DAYS

Fig. 3. Daily observed and predicted production of7-d-old A. domesticus offspring from a breeding colonyof 50 pairs with four pairs (A) and six pairs (B) of newlyemerged crickets added daily.

from a single-aged colony in that a fixed numberofnewly eclosed adult pairs are added each day,resulting in a population with mixed ages. How-ever, once the adult age structure in such a col-ony becomes artiffcially "stable" (i.e., all ageclasses are represented with numbers relative totheir survival expectations), the daily productionof offspring should be sustainable and equal to amultiple of the cumulative net maternity (i.e.,1,407 per cricket pair added). Thus our modelwould predict a harvest of 5,628 and 8,442nymphs per day from colonies in which fourpairs and six pairs, respectively, were addeddaily.

The production-system results (Fig. 3) dis-agreed with our model predictions in that forboth the four-pair and six-pair colonies, the ac-tual sustainable cricket production was substan-tially less than predicted. These differenceswere probably caused by reduced competitiveabilities of the older females in the mixed-agecolonies, In the presence of younger females,older females tended to spend less time aroundthe egg trays and more time in the egg cartonresting places (M.N.P., unpublished data). Theolder females could be recognized by their dark,

o=Eo-U'l!ltoctz

o-!oEotEo

oU'FulYocooz

505040302010

oF 6000LrJvoE 4oooo

9 2ooo

605040302010

0

October 1993 Pena;ur,nr ET AL.: PnooucrroN Moner- ron Acheta domesticus r427

rough, dirty wings compared with lighter, shiny,and cleaner wings of young females. However, itdid not appear that older females experienced anincreased mortality rate in the mass-rearing col-onies compared with the single-aged colonies.

Carey & Vargas (1985) found that in mass rear-ing three species of tephritids, eggs laid after3 wk of adult life contributed little to populationgrowth. To compensate, they invoked an artiff-cially imposed last day of reproduction, termedthe adult discard age. Under our system of dailyintroducing new cricket adults into the breedingcolony, the data from the four-pair colony show a

sharp drop in cricket production on day 24 (FiS.3A), indicating a reduction in oviposition by thefemales in the original 5O-pair cohort and sug'gesting an adult discard age of 24 d. It would notbe practical in our case to actually remove crick-ets from the colonies. However, assuming thatreproduction in a mixed-age colony becomesnegligible after age 24 d, we can impose an ef-fective discard age, which results in a revisedcumuiative net maternity value of I,ll0 offspringper female. With this discard age, our model thuspredicts a harvest of 4,440 and 6,660 nymphs perday for the four-pair and six-pair colonies, re-spectively. In both cases, the experimental re-sults were in general agreement with these pre-dictions. Observed mean daily production was3,995 (t861) and 6,535 (t688) nymphs for thefour-pair and six-pair colonies, respectively, fromdays 25 to 50 of the experiments.

One issue our production experiment did notaddress directly is the sustainability of yieldsbeyond 50 d. We assume that the daily yieldswe observed could be maintained indefinitely.However, although reproduction by older fe-males appears to be reduced in mixed-age colo-nies, survivorship (Fig. 2) may not be similarlyaffected. It is possible that over time, old cricketscould build up to levels at which they wouldinterfere with colony productivity, but this is un-likely because old crickets and the young, pro-ductive crickets appear to compete only for theessentially unlimited number of resting placesprovided by the egg cartons.

Oviposition Substrate Area as a LimitingFactor. We detected no density-dependent de-pression in per-cricket production between thefour-pair and six-pair cages. The area ofoviposi-tion substrate rather than overall cage volumecould be the limiting factor for cricket mass-production, and increasing only this area mightincrease the adult cricket density in a cage be-yond the recommended levels (Patton 1978). Ourresults, however, indicated that the ovipositionsubstrate area was not limiting (Fig. a). Nymphproduction was 3,737 -f 1,555 (mean + SD) whenthe ovipositional surface was reduced by half,and 3,773 -+L,459 when the entire area of thepetri dish was available.

0 10 20 30 40 50 60DAYS

Fig.4. Effect ofreducing the oviposition substratearea by half on the daily production of 7-d-old A. do-mesticus offspring from a colony of 50 pairs with 4 pairsof newly emerged adults added daily.

When the oviposition substrate area was re-duced, the increased density ofcrickets resultedin loss of both oviposition substrate and previ-ously laid eggs by adults kicking substrate out ofthe trays (M.N.P., unpublished data). When alarger surface area was available, there also waskicking of the substrate, but it tended to occurnear the center of the dish, resulting in less sub-strate being kicked out of the dish. The loss ofoviposition substrate is negligible using a lS-cm-diameter petri dish fflled to only three-fourths ofits depth with moistened peat moss. Dry peatmoss is light in weight, which increases the pos-sibility of loss from disturbance.

Acknowledgments

We thank Sharmila Parajulee (University ofWisconsin-Madison) for technical assistance, andJames Carey (University of California, Davis) and twoanonymous reviewers for their helpful comments. Thisresearch was supported in part by the Research Divi-sion, College of Agricultural and Life Sciences, Uni-versity of Wisconsin-Madison (Hatch Project 3038).

References Cited

Andrewartha, H. G. & L. C. Birch. 1954. The distri-bution and abundance of animals. University ofChicago Press, Chicago.

Carey,J. R. & R, I. Vargas. 1985. Demographic anal-ysis of insect mass rearing: a case study of threetephritids. J. Econ. Entomol. 78:523-527.

Clifford, C. W., R. M. Roe & J. P.Woodring. 1977.Rearing methods for obtaining house crickets,Acheta domesticus, of known age, sex, and instar.Ann. Entomol. Soc. Am. 70 69-74.

DeFoliart, G. R. 1989. The human use of insects as

food and as animal feed. Bull. Entomol. Soc. Am.35:2%-35.

Finke, M. D., G. R, DeFoliart & N. J. Benevenga.1989. Use of a four-parameter logistic model toevaluate the quality ofthe protein from three insectspecies when fed to rats. J. Nutr. 119: 864-871.

3 6000DFrllYg 4000Eo

2 2ooo

il

+ HALFSPACE

+ FULLSPACE

1428

Jordan, B. M. & J. R. Baker. f956. The house cricket(Acheta domestica) as a laboratory animal. Ento-mologist 89: 126-127.

McFarlane, J, E. 1962. A comparison of the growthof the house cricket (Orthoptera: Gryllidae) rearedsingly and in groups. Can.J.Zool.40: 559-560.

1964. The protein requirements of the housecricket, Acheta donxesticus L. Can. J. Zool. 42: 645-647.

1985. Acheta domesticus,pp.42T-434' tn P. Singh& R. F. Moore [eds.], Handbook of Insect Rearing,vol. I. Elsevier, Amsterdam.

Nakagaki, B. J. & G. R. DeFoliart. 1991. Compar-ison of diets for mass-rearing Acheta domesticus(Orthoptera: Gryllidae) as a novelty food, and com-parison of food conversion efficiency with valuesreported for livestock. J. Econ. Entomol. 84: 891-896.

Nakagaki,8.J., M.L. Sunde & G. R. DeFoliart. 1987.Protein quality of the house cricket, Acheta domes-ticus, when fed to broiler chicks. Poult. Sci. 66:1367-r371.

National Research Council. 1977. Nutrient require-ments of domestic animals. No. 1: nutrient require-ments of poultry. National Academy of Sciences,Washington, DC.

JOURNAL oF EcoNoMrc ENToMoLocY Vol. 86, no. 5

Parajulee, M. N. & G. R. DeFoliart. 1993. A simplemethod of heat supplementation for cricket mass-rearing in the absence of controlled-temperafureequipment in developing countries. j. Inst. Agric'Anim. Sci. (in press).

Patton, R. L. 1963. Rearing the house cricket,Acheta domesticus, on commercial feed' Ann.Entomol. Soc. Am. 56 250-257'

1967. Oligidic diets for Acheta domesticus (Or-thoptera: Gryllidae). Ann. Entomol. Soc. Am. 60:1238-t242.

1978. Growth and development parameters forAcheta domesticus. Ann. Entomol. Soc. Am. 7I: 40-42.

Polt, J. M. f971. Experiments in animal behavior.Am. Biol. Teach.38: 475-477.

Roe, R. M., C. W. Clifford & J. P.Woodring. 1980.The effect of temperature on feeding, growth, andmetabolism during the last larval stadium of thefemale house cricket, Acheta domesticus. J. InsectPhysiol. 26:639-644.

Taylor, R. L. & B. I. Carter. 1976. Entertaining withinsects, or: the original guide to insect cookery.Woodbridge, Santa Barbara, CA.

Receioed for publication 7 September'7992; ac'cepted 3 Maa 1993.