LARVAL FEEDING FROM SOME ARTIFICIAL DIETS AND ITS EFFECTS ON BIOLOGICAL PARAMETERS OF THE MEDITERRANEAN FLOUR MOTH

678 LARVAL FEEDING FROM SOME ARTIFICIAL DIETS AND ITS EFFECTS ON BIOLOGICAL PARAMETERS OF THE MEDITERRANEAN FLOUR MOTH Mhs Sf*, Mohsen Yzdnin* nd Mohmmd Hssn Sriloo* * Deprtment of Plnt Protetion, Fulty of Plnt Prodution, Gorgn University of Agriulturl Sienes nd Nturl Resoures, IRAN. E-mils: mhssf78@yhoo.om; mohsenyzdnin@gu..ir; mhsriloo@yhoo.o.in [Sf, M., Yzdnin, M. & Sriloo, M. H. 14. Lrvl feeding from some rtifiil diets nd its effets on iologil prmeters of the Mediterrnen flour moth. Munis Entomology & Zoology, 9 (2): 678-686] ABSTRACT: In this study, we evluted the effets of five diets inluding: (1) whet flour + whet rn (3:1 w/w) (FB), (2) whet germ + rewer's yest + glyerol (:1:2 w/w) (MYG), (3) whet germ + rewer's yest (:1 w/w) (MY), (4) whet rn + rewer's yest + glyerol (:1:2 w/w) (BYG), nd (5) whet rn + rewer's yest + glyerol + wter (:5::5 w/w) (BYGW) on some iologil prmeters of the Mediterrnen flour moth, Angst kuehniell. All experiments were done t lortory onditions of 25 ± 2 ºC temp., 7 ± 8% R.H., nd L:D 12:12. Eh experiment repeted four times. Some iologil properties of lrve nd dults investigted. Results showed tht rering diets hd no effet on emryoni development nd perentge egg hth. Highest mens of lrvl period, pre-oviposition period, nd egg to dult emergene period; nd lowest mens of weight of mle nd femle lrve, pupe, nd dults, femle feundity, nd dult mles' nd femles' longevity were oserved on BYG diet. In ontrst, highest mens of femle feundity, perentge of survivl from egg to dult, weight of lrve, pupe nd dults, nd dult longevity, nd lowest mens of per-oviposition period, lrvl period, nd egg to dult emergene period oserved on FB nd MYG diets. Bsed on these prmeters, FB nd MYG diets (MYG without onsidering the eonomi osts) re the est diets for rering the Mediterrnen flour moth. KEY WORDS: Mediterrnen flour moth, rtifiil diet, iologil properties. The Mediterrnen flour moth Angst kuehniell (Zeller), s enefiil inset, hs its own signifine oth in mss-rering progrms of prsitoid wsps; nd in physiologil, toxiologil, nd eologil investigtions. This moth nd other stored-produt moths nd eetles re often used in lortories with the im of studying inset life histories nd dult mting strtegies (Ryne et l., 4). These insets re osmopolitn nd re le to develop in different ommodities nd hve dpted to live in high densities nd on undnt ut poor diets (Tremterr, 1997). By literture review, it ws reveled tht in those lortory experiments in whih this inset nd its losely relted speies, the Almond moth Ephesti utell (Wlker), were used for purposes other thn mss rering, lrve were rered on stndrd rtifiil diets inluding whet germ, glyerol, dried yest nd whet rn (eg. Cook et l., 1997; Sski & Ishikw, 1999; Iked et l., 3; Ryne et l., 4) insted of nturl diets of whet flour nd rn or flours nd kernels of other grins. This is minly done to eliminte the unreognizle nd vrile effets of nturl diets (Ryne et l., 4). In inset rtifiil dies, glyerol is dded s n dditionl nutrient to prevent mold growth (Norris, 1934; Bell, 1975) nd to t s humetnt euse first instrs rrely survive if dietry moisture is too low (Benson, 1973). Some rtifiil diets suh s n rtifiil one onsisting of hyrid ommeril yellow mize nd yest nd diet ontining white mize with very high lysine nd

679 tryptophn ontents dded to yest n use for mss rering of Trihogrmm spp. on A. kuehniell (Mgrini et l., 1995). Due to this nd euse of lking ny omprehensive investigtion regrding the effets of these diets on the iology of this inset, the present study rried out to ompre seleted rtifiil diets with nturl food ontining whet flour nd rn, nd lso to pve the wy for hoosing the est nd the most pproprite rtifiil diet in prospetive reserhes with eologil, toxiologil, nd physiologil ims. MATERIALS AND METHODS Inset ulture To fulfill the projet, newly lid eggs (mx. 24 hrs old) of A. kuehniell were used. The lrve rered on whet flour for 5 genertions. Experimentl onditions were s 25±2 ºC Temp., 7 ± 8% R.H., nd L12: D12. Food tretments The ingredients of diets in the present study inluded whet flour, whet rn, whet germ, rewer's yest, nd glyerol. The tretments omprised of: (1) whet flour + whet rn (FB) (3:1 w/w) (Yzdnin et l., ); (2) whet germ + rewer's yest + glyerol (MYG) (:1:2 w/w) (Ryne et l., 4); (3) whet germ + rewer's yest (MY) (:1 w/w) (Ryne et l., 4); (4) whet rn + rewer's yest + glyerol + wter (BYGW) (:5::5 w/w) (Iked et l. 3); nd (5) whet rn + rewer's yest + glyerol (BYG) (:1:2 w/w) (Sski & Ishikw, 1999). The experiments onduted in one-wy ANOVA with four replitions. Biologil prmeters In this study, we investigted the following iologil prmeters: lrvl period durtion (the dys etween the oservtions of first instrs to emergene of the first pup); weight of fifth instrs, pupe, nd dult mles nd femles (weighting of individuls from eh developmentl stge; in the se of fifth instrs, those who were finished their feeding were seleted); feundity (rndom seletion of 25 pirs of mles nd femles with mximum longevity of 12 hrs from eh tretment nd ounting eggs lid every dy); Mle nd femle dults' longevity, proportions of eggs hthed, nd survivl from egg to dult (rering of eggs in eh replition nd lulting the perentge of survivl using the formul: Survivl % = [No. of dults emerged/no. of eggs] ). Dt nlyses The dt were nlyzed y using the MSTAT-C sttistil softwre (ver. 2.). Mens were seprted y using the LSD test, t P =.1. RESULTS AND DISCUSSION Lrvl period In the present study, the shortest nd longest lrvl periods oserved in MYG (14. dys) nd BYG (23.75 dys) diets (F4,15 = 57.49; P =.) (Fig. 1). Yzdnin et l. () reported tht in moisten diets (12% moisture ontent), lrvl period delined ompred to dry diets (8% moisture ontent). Aording to our results, in diets ontining glyerol, due to provision nd retention of moisture y glyerol (Ryne et l., 4), lrve ontriute less energy for feeding nd produing metoli wter nd their food needs re provided t higher speed. As result, lrvl period dereses (Yzdnin et l., ). On the other

68 hnd, in diets ontining whet rn, due to its toughness, the lrve (espeilly firs instrs) feed hrdly on them nd onsequently lrvl period prolongs (Yzdnin et l., ). Adding wter to BYG diet (the BYGW diet), euse of providing more food moisture, deresed the lrvl period signifintly (Fig. 1). Weight of fifth instrs mle nd femle lrve The min effets, diet (F4,3 = 17.52) nd sex (F1,3 = 18.17) were highly signifint (P.2). However, the ssoited intertion, diet sex (F4,3 = 1.75) ws not signifint (P =.165). Aording to the results of this investigtion, the highest weights for fifth instrs mle nd femle lrve oserved in MYG (26.6 nd 28.46 mg), MY (26.64 nd 27.52 mg), nd FB (21.55 nd 26.58 mg) diets while the lowest ones oserved in BYG (.4 nd 21.45 mg) diet (Fig. 2). In ll investigted diets, femle lrve weighed more thn mle ones. Yzdnin et l. () reported tht rering the lrve on diets ontining whet flour + whet rn (3:1 w/w), whet flour, whet flour + whet rn (1:1 w/w), nd whet flour + whet rn (1:3 w/w) resulted to the highest weight of fifth instrs mle nd femle lrve, respetively. They justified the mximum growth on diet ontining 25% rn with the ft tht only fifth instrs were ple of feeding on rn nd this together with the nutrient rihness of rn ompring to flour hve inresed the lrvl ody weight. In diets lking rn, though lrve fed well on them, they weighed less due to lk of nutrients. In diets ontining higher mounts of rn, euse of feeding of first, seond nd third instrs on rough prtiles of rn, nd euse of tension imposed on them, more ody weight loss is depited tht their lter effets re shown in pupe nd dults. Ziie Mdooni & Frshf Pour Ad (12) did not oserve ny signifint differene in lrvl ody weight y rering the A. kuehniell on different ultivrs of whet (Rsd, Shiroodi, Tjn, Gowhdsht, Niknejhd, N-8-19, Zgros, Azr 2, Srdri, nd Art), exept for Shiroodi nd Art. In these two ultivrs, euse of insuffiient flour ville to lrve, their ody weight deresed. The kernels of these two ultivrs hve high moisture ontents nd roughness, nd re not well grind. As result, lrve espeilly erly instrs nnot feed properly. In the present study, feeding of erly instrs from BYG diet deresed lrvl ody weight due to the presene of rn in the diet nd feeding stresses y onsuming it. Adding wter to this diet (BYGW diet) helped to inrese lrvl ody weight (for femle lrve signifintly). In MYG nd MY diets, the presene of rewer's yest nd whet germ, whih re two sustnes ontining vitmins, ould led to higher ody weight. In ll diets, femle lrve weighed more thn mle ones tht this orresponds to Yzdnin et l. () nd Eyvzin Kri (1). Weight of mle nd femle pupe As for the previous iologil prmeter, the min effets, diet (F4,3 = 18.15) nd sex (F1,3 = 11.91) were highly signifint (P.17) nd the ssoited intertion, diet sex (F4,3 = 1.17) ws not signifint (P =.345). Highest weights of mle nd femle pupe oserved in MYG (24.5 nd 27.83 mg) nd MY (21.77 nd 25.9 mg) diets nd the lowest mounts oserved in BYG (15.3 nd 17.88 mg) diet (Fig. 3). Rodriguez et l. (1988) rered the lrvl A. kuehniell on four seeds (soyen, rley, whet, nd orn) nd two vitmin ontining foods (whet germ nd red yest) nd oserved tht dding whet germ nd red yest to diet inresed ody weight of femle pupe. Furthermore, ody weight of femle pupe ws higher thn tht of mle pupe. In our study, this is lso true out the mle pupe. They suggested tht in A.

681 kuehniell, weight of pupe is relted to the lrvl diets. Higher ody weight of femle pupe ompring to the mle ones is in orreltion with femle nd mle lrvl ody weight from whih they hve evolved. Weight of mle nd femle dults In this se, not only the min effets, diet (F4,3 = 72.3) nd sex (F1,3 = 3.52) were highly signifint (P =.), ut the ssoited intertion, diet sex (F4,3 = 21.6) ws lso highly signifint (P =.). As for the two previous iologil prmeters, highest ody weights for mle nd femle dults oserved in MYG (15.16 nd 22.49 mg) nd MY (12.54 nd.5 mg) diets, nd the lest ones oserved in BYG (8.57 nd.31 mg) diet (Fig. 4). Yzdnin et l. () reported tht highest mens of mle nd femle dults' ody weight rered on different diets ontining different proportions of whet flour nd rn vried from 9.4 up to 15.13 mg for mles, nd from 15.39 up to 21.53 mg for femles tht showed signifint differene. In their study, dry nd moisten diets (with 8% nd 12% moisture ontent, respetively) hd no effet on ody weight. Eyvzin Kri (1) lso reported mens from 12.42 up to 17.31 mg nd from 17.11 up to 23.96 mg for mle nd femle dults, respetively, rered on diets ontining whet flour nd rn. Vieir et l. (1995) reported tht the mle nd femle dult weight on three different textures of mize flour (fine, medium, nd orse) were 13.19, 14.77, nd 12.38 mg for mles nd 19.37, 21.81, nd 18.3 mg for femles. In n experiment with soft whet flours with the sme nutritionl vlue ut different prtile size, rering on smples with gretest prtile size (25-419 μm) used the highest men numer of dults nd the shortest developmentl period (Lotelli et l., 8). This inset prefers flours (Yzdnin et l., ; Eyvzin Kri, 1) nd it is suggested tht prtile size of flours with the sme nutritionl vlue determines the suitility of flour for this speies. Like fifth instrs nd pupe, nd in ll tretments, femle dult weight ws more thn tht of mle ounterprts. The signifine of the intertion of two min effets (i.e. diet sex) on dults' ody weight (ut not on the weights of lrve nd pupe) revels the prole different effiienies of digested food y nd hene in the digestive physiology of mle nd femle lrve, whih ffet the dult stge. Feundity Aording to results, the higher oviposition rte (eggs/femle) oserved in FB (325.76 eggs), MYG (295.72 eggs), MY (234.4 eggs), BYGW (5.56 eggs), nd BYG (5.56 eggs) diets, respetively (F4,1 = 27.8; P =.) (Fig. 5). These results re orrelted with mens of femles' ody weight. Solis et l. (6) reported tht feundities of A. kuehniell on three rtifiil diets: orn mel, red rum, nd mixture of oth in equl proportions were equl to 3.82, 154.42, nd 226.62 eggs/femle, respetively. In reserh y Yzdnin et l. (), the numer of eggs lid y femles rered on dry nd moisten diets of: whet flour + whet rn (3:1), whet flour, whet flour + whet rn (1:1), nd whet flour + whet rn (1:3) were respetively evluted s 347.37 & 354, 297.3 & 316.97, 28. & 288., nd 264. & 269. eggs/femle. The numer of eggs per femle y rering lrve on different diets ontining whet flour nd rn (Eyvzin Kri, 1) vried from 289 up to 411. Deresing the feundity of this speies due to the feeding of lrve on rough food prtiles nd weight loss of femle dults s e result re in ordne with Yzdnin et l. () nd Eyvzin Kri (1) findings.

682 Mle nd femle dults' longevity ANOVA of dt showed tht the min effet, diet (F4,24 = 19.1) nd the ssoited intertion, diet sex (F4,24 = 4.21) were highly signifint (P.26). However, the other min effet, sex (F1,24 = 3.36) ws not signifint (P =.68). Mle nd femle dults lived longer in FB (.44 nd 8.92 dys) nd MYG (.32 nd 8.92 dys) diets, respetively, ut died sooner in MY (8.8 nd 7.48 dys), BYG (7.52 nd 7.48 dys), nd BYGW (7.3 nd 6.36 dys) diets (Fig. 6). In ll tretments, mles lived longer thn femles, ut the differenes were not signifint. Kind of diet my hve no effet on dult longevity (e.g. Ayvz & Krörklü, 8). In their experiment, Flp et l. (1995) rered four groups of A. kuehniell dults inluding: (1) pirs with free mting, no feeding; (2) pirs with free mting, feeding from honey; (3) pirs llowed to mte one, no feeding; nd (4) virgin dults, no feeding. They oserved tht in ll investigted groups, mle dults' longevity (out 12 dys) ws longer thn tht of femles (out 9 dys). Ryne et l. (4) studied the effets of glyerol on feundity nd longevity in the lmond moth, Ephesti utell (Wlker). Their results showed tht lrvl diets ontining glyerol (wet lrvl diets) signifintly inresed mle nd femle longevity. It is suggested tht glyerol in inset diets is n inert dditionl nutrient (Bell, 1975; Benson, 1973) nd euse of its positive effet on moisture retention inreses the qulity of diets (Benson, 1973). Yzdnin et l. () nd Eyvzin Kri (1) lso reported tht in this speies, mle lived longer thn femles. This phenomenon ould possily e result of oviposition (one of the most energy-demnding tivities) on femles. Proportion of eggs hthed In ll tretments, egg hthility evluted equl to %. In the reserh y Solis et l. (6), proportion of eggs hthed in the A. kuehniell rered on three rtifiil diets: orn mel, redrum, nd mixture of oth in equl proportions were equl to 59.3, 85.3, nd 9.3 per ent, respetively. Their results differ with our findings nd this differene might e due to rering of lrve on rough nd orse diets y Solis et l. In experiments rried out y Yzdnin et l. () nd Eyvzin Kri (1) on this inset nd diets sed on whet flour nd rn, proportions of eggs hthed vried respetively from 88.5 up to 9. per ent, nd from 89.75 up to 91.5 per ent with no signifint differene. Proportions of eggs hthed reported y Amrl Filho & Hi (199), Rodrigeuz Filho et l. (1991), nd Jo & Cox (1977) re 92.54, 98., nd 97. per ent, respetively. Vinuel & Mro (199) stted tht presene of food hs the highest effet on egg hthing nd emergene of lrve even if there is no diret ontt etween eggs nd food. Thus, we n sy tht food odor is one of stimulnts tht enourge lrve to leve the eggs nd sene of the odor n derese proportion of eggs hthed. Survivl from egg to dult The higher survivl rtes from egg to dult oserved in MYG (98.%), MY (92.25%), nd FB (92.%) diets, nd the lowest mens oserved in BYG (65.5%) nd BYGW (73.75%) (F4,15 = 33.94; P =.) (Fig. 7). Aording to our results, the presene of rn hd negtive effet on survivl rte. This finding is in ordne with Yzdnin et l. () nd Eyvzin Kri (1) who stted tht this inset prefers flours. Results otined from the present study indited tht onsidering the importnt iologil prmeters while rering the Mediterrnen flour moth, nd

683 lso onsidering the eonomi osts, the nturl diet ontining whet flour + whet rn (3:1) is the est for mss rering of ioontrol gents on eggs nd lrve of this moth. In ddition, this diet is prepred fst nd esy nd its onstituents re esily ville. In smll-sle rering in reserh lortories, using the MYG diet is reommended for ims other thn mss rering of nturl enemies suh s for rrying out investigtions e.g. physiologil, eologil, nd toxiologil studies. ACKNOWLEDGEMENTS We relly ppreite the finnil support y the Gorgn University of Agriulturl Sienes nd Nturl Resoures for the present reserh. LITERATURE CITED Amrl Filho, B. F. & Hi, M. E. M. 199. Biologi de Angst kuehniell (Zeller, 1879) (Lepidopter, Pyrlide). Revist de Agriultur (Piri), 65 (2): 133-143. Ayvz, A. & Krörklü, S. 8. Effet of old storge nd different diets on Ephesti kuehniell Zeller (Lep.: Pyrlide). Journl of Pest Siene, 81: 57-62. Bell, C. H. 1975. Effet of temperture nd humidity on development of for pyrlid moth pests of stored produt. Journl of Stored Produt Reserh, 11: 167-175. Benson, J. F. 1973. The iology of Lepidopter infesting stored produts, with speil referene to popultion dynmis, Biologil Reviews, 48: 1-26. Cook, P. A., Hrvey, I. F., & Prker, G. A. 1997. Prediting vrition in sperm preedene. Philosophil Trnstions of the Royl Soiety of London, B, 352: 771-78. Eyvzin Kri, N. 1. Lortory evlution of dding red yest to lrvl diets nd dult feeding from sugr onentrtions in the Mediterrnen flour moth, Ephesti kuehniell Zeller, nd its effets on some iologil properties of the moth. M. S. Thesis, Fulty of Agriulture, Triz University, 83 pp. (in Persin). Flp, L., Vieir, V. & Tvres, J. 1995. Some reprodution spets of Ephesti kuehniell Zeller (Lepidopter: Pyrlide) under mss rering onditions. Avnes en Entomolí Iéri, pgs. 367-374. Iked, T., Ishikw, H. & Sski, T. 3. Regultion of Wolhi density in the Mediterrnen flour moth, Ephesti kuehniell, nd the Almond moth, Cdr utell. Zoologil Siene, (2): 153-157. Jo, T. A. & Cox, P. D. 1977. The influene of temperture nd humidity on the life-yle of Ephesti kuehniell Zeller (Lepidopter: Pyrlide). Journl of Stored Produt Reserh, 13: 7-113. Lotelli, D. P., Limont, L. & Stmpini, M. 8. Effet of prtile size of soft whet flour on the development of Ephesti kuehniell Zeller (Lepidopter: Pyrlide). Journl of Stored Produt Reserh, 44: 269-272. Mgrini, E. A., Prr, J. R. P. M., Hddd, I. & Botelho, P. S. M. 1995. Compro de diets rtifiiis e tipos de milho pr rio de Angst kuehniell (Zeller, 1879) (Lepidopter: Pyrlide). Sienti Agriol, 52 (1): 6-64. Norris, M. J. 1934. Contriutions towrd the study of inset fertility. III. Adult nutrition, feundity nd longevity in the genus Ephesti (Lepidopter, Phyitide). Proeedings of the Zoologil Soiety of London, 1-2: 333-36. Rodriguez Filho, I. L., Hddd, M. L., Pr, J. R. P. & Stein, C. P. 1991. Compro de diets umid e se pr rio de Angst kuehniell (Zeller, 1879). Anis d Soiedde Entomológi do Brsil, (2): 417-425. Rodriguez, M. H., Cello, G. T. & Vrgs, P. 1988. Influeni de l diet en el desrrollo de Ephesti kuehniell Zeller (Lepidopter: Phyitide). Boletín de Snidd Vegetl Plgs, 14 (4): 363-369.

Lrvl period (dys) 684 Ryne, C., Nilsson, P. A. & Siv-Jothy, M. T. 4. Dietry glyerol nd dult ess to wter: effets on feundity nd dult longevity in the lmond moth. Journl of Inset Physiology, 5: 429-434. Sski, T. & Ishikw, H. 1999. Wolhi infetions nd ytoplsmi inomptiility in the Almond moth nd the Mediterrnen flour moth. Zoologil Siene, 16 (5): 739-744. Solis, D. R., Hi, M. E. E. D., Fernndes, E. S. A., Heling, M. J. A., & d Silv, T. F. 6. Estudo omprtivo do desenvolvimento de Angst kuehniell (Zeller, 1879) (Lepidopter, Pyrlide) em tres diets rtifiiis. Revist Brsileir de Zooiênis, 8 (1): 17-22. Tremterr, P. 1997. Integrted pest mngement of stored-produt insets: prtil utiliztion of pheromones. Anzeiger für Shädlingskunde Pflnzenshutz Umweltshutz, 7: 41-44. Vieir, V., Flp, L. & Tvres, J. 1995. Epigeneti vriility of Ephesti kuehniell Zeller (Lepidopter, Pyrlide) under mss rering onditions. In: Avnes en Entomologí Iéri (ed. Comité editoril). Museo Nionl de Cienis Nturles (CSIC) y Universidd Autónom de Mdrid. pp. 491-5. Vinuel, E. & Mro, V. 199. Efeto de lgunos ftores sore l elosion de huevos de Ephesti kuehniell Zeller, 1879 (Lepidopter: Pyrlide). SHILAP Revist de Lepidopterologí, 18 (72): 317-324. Yzdnin, M., Tlei-Chihi, P. & Hddd Irni-Nejhd, K.. Studying development of the Mediterrnen flour moth, Ephesti kuehniell, rered on some diets ontining whet flour nd rn. Agriulturl Siene, (3): 35-48 (in Persin). Ziie Mdooni, M. A. & Frshf Pour Ad, R. 12. Effet of different whet vrieties on some of developmentl prmeters of Angst kuehniell (Lepidopter: Pyrlide). Munis Entomology nd Zoology, 7 (2): 17-22. 25 15 19.5 14. d 21.5.5 23.75 5 Figure 1. The effet of different lrvl diets on lrvl period.

Adult's ody weight (mg) Pupl ody weight (mg) Lrvl ody weight (mg) 685 3 25 26.58 21.55 28.46 26.6 27.52 26.46 25.59 22.45 21.45.4 Femle Mle 15 5 Figure 2. Lrvl ody weight fter feeding from different diets y lrve. 3 25 15 22.69 22.25 27.83 24.5 25.9 21.77 21.35 d 16.55 de 17.88 de 15.3 e Femle Mle 5 Figure 3. Pupl ody weight fter feeding from different diets y lrve. 3 25 15 5 17.55 11.91 22.49 15.16.5 12.54 11.88.61 d.31 8.57 d d Femle Mle Figure 4. Adult's ody weight fter feeding from different diets y lrve.

Survivl from egg to dult (%) Adults' longevity (dys) Feundity (eggs/femle) 686 35 3 25 15 5 325.76 295.72 234.4 5.56 5.56 d Figure 5. The signifint effet of different lrvl diets on femle feundity. 12 8 6.44.32 8.92 8.68 d e 7.48 de 8.8 d 6.36 e 7.3 7.48 7.52 e de de Femle Mle 4 2 Figure 6. Adult longevity is ffeted y feeding of lrve from different diets. 1 8 6 92. 98. 92.25 73.75 65.5 4 Figure 7. Lrvl feeding from different diets nd its signifint effet on survivl from egg to dult prmeter.