Percentage Of Pupae Research Articles

Development of immature tiger-fly Coenosia attenuata (Stein) reared on larvae of the fungus gnat Bradysia impatiens (Johannsen) in coir substrate

The development of immature tiger-fly Coenosia attenuata (Stein) was examined when reared in coir substrate and fed third-instar larvae of the fungus gnat Bradysia impatiens (Johannsen). Single larvae of C. attenuata were fed 3, 5, 7 and 9 prey per day and two larvae were fed 6, 10, 14 and 18 prey per day. Optimal prey density was determined for larval developmental rate, time to adult eclosion, larval survival, and percentage of pupation. Other biological characteristics, such as pupal weight, pupal length, and adult body length, continued to increase with an increase in prey density. The use of coir for a rearing substrate resulted in a more efficient use of prey, less cannibalism, and improved developmental time, and survival than previously reported when agarose gel or a mixture of soil and coir were used for rearing substrates. These improvements in rearing methods are significant advancements for the use of C. attenuata as a biological control agent against whiteflies, leaf miners, fungus gnats and winged-aphids. Additionally, coir substrate serves as a mulch layer when fungus gnats are controlled with C. attenuata, such as Bradysia odoriphaga (Yang et Zhang) in Chinese chive, and B. impatiens in potted ornamental plants.

EFFICIENCY OF CERTAIN PESTICIDES ON SOME BIOLOGICAL ASPECTS OF SPODOPTERA LITTORALIS (BIOSD) UNDER FILED AND LABORATORY CONDITIONS

Efficiency of four pesticides belonging to different groups of chemicals ,namely : Chlorosan, Agrinate , Daizinone and Nasractine on some biological aspects of 2nd and 4th instar larvae of the cotton leaf worm S. littoralis (Boisd) under field and laboratory conditions were investigated . The LC50 and LC 90 values were calculated after 24 , 48 , and 72h. Post – treatment . The obtained results showed that a wide range of toxicity of the tested pesticides , however the insecticide Chlorosan proved itself to be the highest toxic compound to the treated larvae as LC50 and LC90 values after 72h. post – treatment recording 0.01 , 0.83 ppm and 0.13 , 5.23 ppm for 2nd and 4th instar larvae , respectively . On the other hand , the compound Diazinon exhibited the lowest toxicity to the tested larvae at the both levels of toxicity (LC50 and LC90 values after 72h. were 16.86 ,69.31 ppm and 39.59 , 186.67 ppm) for 2nd and 4th instar larvae , respectively . The other tested pesticides occupied an intermediate position. The tested pesticides increased the larval , pupal duration and malformed pupae and decreased the percentage of pupation , adult emergence compared with control.

Pea protease inhibitor inhibits protease activity and development of Bactrocera cucurbitae

Melon fruit fly, Bactrocera cucurbitae (Coquillett) is an important pest of cucurbit crops that can cause severe damage to its host species and thus drastically reduce the crop production. In recent years, protease inhibitors have been extensively explored against lepidopteran and some coleopteran insects and have shown significant inhibitory effects against them. They are therefore increasingly being explored for enhancing resistance in crops to insect pests. In the present study, bioassays conducted with pea protease inhibitors showed significant adverse effect on the development and physiology of the larvae of melon fruit fly. The incorporation of different concentrations (12.5, 25, 50, 100, 200 and 400μg/mL) of the pea protease inhibitor into the artificial diet of second instar (64–72h old) larvae, had significant inhibitory effects (p<0.01) when monitored through bioassays for various growth parameters such as larval period, total development period, pupal weight, percentage pupation and percentage emergence as compared to control. Enzymatic assays at different concentrations (50, 100, 200 and 400μg/mL) of pea protease inhibitor (PI) significantly reduced the activities of digestive enzymes (trypsin, chymotrypsin, leucine aminopeptidase and elastase) with an increase in treatment interval.

Light conditions affect the performance of Yponomeuta evonymellus on its native host Prunus padus and the alien Prunus serotina.

The bird cherry ermine moth, Yponomeuta evonymellus L., is considered an obligatory monophagous insect pest that feeds only on native European Prunus padus L. In recent years, however, increased larval feeding on alien P. serotina Ehrh. has been observed. In both species, general defoliation is extensive for shade grown trees, whereas it is high in P. padus, but very low in P. serotina, when trees are grown in full light conditions. The aim of the present study was to identify how the plant host species and light conditions affect the performance of Y. evonymellus. The influence of host species and light condition on their growth and development, characterized by the parameters of pupation, adult eclosion, body mass, potential fecundity, and wing size, was measured in a 2 × 2 experimental design (two light treatments, two hosts). In comparison with high light (HL) conditions, a greater percentage of pupation and a longer period and less dynamic adult emerge was observed under low light (LL) conditions. The effect of host species on these parameters was not significant. In contrast, mass, fecundity and all of the studied wing parameters were higher in larvae that grazed on P. padus than on P. serotina. Similarly the same parameters were also higher on shrubs in HL as compared with those grown under LL conditions. In general, light conditions, rather than plant species, were more often and to a greater extent, responsible for differences in the observed parameters of insect development and potential fecundity.

Effect of Beauveria bassiana and Metarhizium anisoplae on some biological aspect of Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae)

This experiment were carried out to study the effect of treatment of newly hatched (neonate) larvae and pupae of the pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) with different entomopathogenic fungi; Biover (Beauveria bassiana) and Bioranza (Metarhizium anisoplae) was investigated under laboratory conditions of 27 ± 1o C and 65 % ± 10 % R.H. The results show that P. Gossypiella was susceptible to both fungi. LC50 values obtained were1.42 and 0.98 glfor P. Gossypiella larvae treated with different concentrations of B.bassiana and M.anisopilae, respectively. The biological aspects of P. gossypiella were affected when treating the newly hatched larvae with the LC50's of both fungi. Results generally revealed changes in the different biological aspects (larval duration, pupation percentage, pupal duration and the percentage of adult emergence). Determine the effect of B. bassiana and M. anisopliae on the prey consumption rate of Oriusa lbidipennis to pink bollworm eggs.

Lethal and sublethal effects of mixtures of entomopathogenic fungi and synthetic insecticides on biological aspects of Musca domestica L.

The current study was performed to assess the effectiveness of the entomopathogenic fungi Metarhizium anisopliae var. anisopliae (Metschnikof) Sorokin and Isaria fumosorosea (Wize) Brown&Smith applied in combination with some synthetic insecticides against the house fly, Musca domestica L. (Diptera: Muscidae) at Department of Entomology, Bahauddin Zakariya University, Multan, Pakistan during 2015. An extensive, typically dose-dependent range of responses was shown by flies towards fungus-synthetic insecticide combinations using a bait method. The insecticides acetamiprid, emamectin benzoate, imidacloprid and lufenuron in combination with insect pathogenic fungi showed higher mortality than expected with significant synergistic interactions. In addition, the mixtures were also assessed for sublethal effects on biological parameters of M. domestica , namely adult longevity, fecundity, egg hatching, larval duration, percent pupation, pupal weight, pupal duration, adult emergence and sex ratio. The results showed a considerable impact of fungi and synthetic insecticide mixtures on all biological parameters of M. domestica (P<0.05) except adult emergence. A noteworthy reduction in adult longevity, fecundity, egg hatching, percent pupation and pupal weight was observed, while larval and pupal durations were prolonged. The results highlight the potential of combined use of entomopathogenic fungi and synthetic insecticides for the control of M. domestica . Moreover, the combination of entomopathogenic fungi and synthetic insecticides can reduce the concentrations of the active ingredient required to achieve the same result as when these are applied separately. However, field trials are required to validate the effects of entomopathogenic fungi and synthetic insecticides mixtures before they can be recommended as elements of an integrated pest management program for M. domestica .

Biological and histopathological effects of cyromazine on the laevae of Culex pipiens (Diptera Culicidae).

Laboratory studies were carried out to investigate the efficacy of the chitin synthesis inhibitor (cyromazine) against all larval stages of Culex pipiens. The compound was tested its efficacy on larval mortality, larval duration, pupation, pupal duration and adult emergence. Also, the histological effects of cyromazine on the midgut, the integument, the fatbodies and the muscles of 4th larval instar treated as 1st larval instar were studied. The tested compound increased the larval mortality, decreased the percent pupation and adult emergence and prolonged the pupal duration. Also, this compound elicited histological effects on the midgut, the integument, the fat bodies and the muscles of 4th larval instar of C. pipiens treated as 1st larval instar with 0.01 and 0.1 ppm.

Biological and physiological effects of Coriandrum sativum on House fly Musca domestica (Diptera: Muscidae)

This Study is conducted to evaluate effects of (leaves, fruits) powder and (oil, alcohol) extract of Coriander (Coriandrum sativum) plant on some biological and physiological aspects of House fly, Musca domestica at laboratory conditions. Result show that these preparations caused biological effects represented in high dead percentage in second instar, fed on different concentrations of food treated with them reached to 27.6, 55.3 at concentration 20% of leaf and fruit powder respectively and 67.3, 77.2% at 10% of oil and alcohol extract of fruit, respectively. Furthermore, study also show reduction in pupation and adults emergence percentage. However, leafs powder had slighter effect than powder and extract of fruit of tested plant. The study show physiological effects in treated larvae such as molting failure at subsequent molt to larvae , pupa or to adult, also morphological aberration represented in small size, dark pigment, reduce age and folding of the adult wings. In almost cases, the higher concentration the more morphogenetic aberration. This study leads us to conclude that coriander had chemical compounds which played a negative role in some biological and physiological aspects of house fly.

Effects of tea saponin on growth and development, nutritional indicators, and hormone titers in diamondback moths feeding on different host plant species

The diamondback moth (DBM) is an important worldwide pest. This insect has been studied for several decades; however, its control remains problematic. Numerous chemical insecticides have become ineffective and chemical residues constitute an important problem. In the present study, we determined the mortality of 3rd instar DBM larvae feeding on three different host plant species and exposed to various concentrations of tea saponin (TS). In addition, we evaluated growth and development parameters, nutritional indicators, and juvenile hormone (JH) and molting hormone (MH) titers in 2nd instar larvae exposed to LC20 and LC50 doses of TS. We found that treatment of DBM larvae with LC20 and LC50 doses of TS led to lower growth rates, decreased feed consumption, reduced frass production, lower pupal weights, reduced percentage pupation, slower adult emergence percentages, and diminished fecundity, but prolonged durations of the larval and pupal periods. The efficiency of conversion of ingested and digested food increased, but the approximate digestibility did not differ significantly between treatments and controls. JH and MH titers were higher after TS treatment; these increases varied according to the host species and TS concentration. Our results indicate that TS represents a potential new alternative insecticide based on its natural origin, low cost, and minimum environmental impact.

Biological and physiological effects of Coriandrum sativum on House fly Musca domestica (Diptera: Muscidae)

This Study is conducted to evaluate effects of (leaves, fruits) powder and (oil, alcohol) extract of Coriander (Coriandrum sativum) plant on some biological and physiological aspects of House fly, Musca domestica at laboratory conditions. Result show that these preparations caused biological effects represented in high dead percentage in second instar, fed on different concentrations of food treated with them reached to 27.6, 55.3 at concentration 20% of leaf and fruit powder respectively and 67.3, 77.2% at 10% of oil and alcohol extract of fruit, respectively. Furthermore, study also show reduction in pupation and adults emergence percentage. However, leafs powder had slighter effect than powder and extract of fruit of tested plant. The study show physiological effects in treated larvae such as molting failure at subsequent molt to larvae , pupa or to adult, also morphological aberration represented in small size, dark pigment, reduce age and folding of the adult wings. In almost cases, the higher concentration the more morphogenetic aberration. This study leads us to conclude that coriander had chemical compounds which played a negative role in some biological and physiological aspects of house fly.

Screening and classification of mulberry silkworm, Bombyx mori based on thermotolerance

The tropical climate prevailing in India adversely affects temperate bivoltine silkworm rearing and causes crop loss especially during summer. Identification of high temperature tolerant bivoltine breeds by screening for thermotolerance in the silkworm, Bombyx mori (Lepidoptera: Bombycidae) is an essential prerequisite for the development of thermotolerant bivoltine breeds / hybrids. Therefore, in this study, 20 silkworm breeds were reared at different temperatures (25 ± 1°C,32 ± 1°C, 34 ± 1°C and 36 ± 1°C) for 6 h every day from 3 rd d of th instar to till spinning. Significant differences ( p < 0.01) were found among all the rearing traits over temperature. Based on pupation percentage, SK4C and BHR3 were identified as thermotolerant bivoltine breeds. Hierarchical clustering analysis based on rearing traits at tested temperatures grouped 20 silkworm breeds in four clusters which included one cluster each of susceptible and tolerant, and two clusters of moderately tolerant silkworm breeds. This suggests that clustering based on rearing data at high temperatures by using Euclidean distance can be an effective approach in classifying the silkworm breeds on their thermotolerance capacity. The identified breeds would be used for development of thermo tolerant bivoltine silkworm breeds / hybrids.

ACTIVITY OF CASTOR OIL SEEDS Ricinus communis ETHANOL EXTRACT AGAINST COTTON LEAFWORM Spodoptera littoralis (BOISD.)

The present work aimed to study the effect of ethanol extract of Ricinus commnuis L. seeds on biological and physiological aspects for the cotton leafworm Spodoptera littoralis, 2nd and 4th instar larvae. The results cleared that the larval duration was 17.08 and 15.58 days & 10.11 and 9.36 days for treated and the untreated 2nd & 4th instar larvae respectively. The pupation percentage was 60.0 and 96.0 % for treated and untreated 2nd instar larvae and 61.0 and 93.0 for treated and untreated 4th instar larvae. The pupal weight was affected by the botanical extract. The pupal duration was 11.40 and 11.71 days for treated and untreated 2nd instar larvae and it was 11.96 and 12.51 days for treated and untreated 4th instar larvae. The emergence percentages resulted from treated 2nd and 4th instar larvae were 82.0 and 85.2 % compared with 97.0 % and 92.0 % for that resulted from the untreated larvae, respectively. On the other hand, the malformed adult was 28.0 and 2.0 % for 2nd instar larvae (treated and untreated) and 16.0 and 5.0 % for 4th instar larvae (treated and untreated) respectively. There are decreasing in fecundity of S. littoralis adults resulted from the treated 2nd and 4th instar larvae by the botanical extract used for this study. Effect of LC50 value of the tested plant extract on the biochemical aspects of the 4th larval instar of S. littoralis was detected. The biochemical aspects AST, ALT, alkaline and acid phosphatase activities, the as well as the total protein content post treatment of the 4th instar larvae were considered throughout the present study.

Analysis of transcripts of heat shock protein genes in silkworm, Bombyx mori (Lepidoptera: Bombycidae)

Silkworm is a poikilothermic insect, whose growth and development is significantly affected by high temperatures. The current study aimed to identify bivoltine breeds tolerant of the high temperature conditions that occur in the tropics. Percentage pupa- tion at high temperatures and heat shock responses of silkworms were used as measures of thermotolerance. Thermotolerance of 20 silkworm breeds was assessed by rearing them at 36°C. Based on percentage pupation, three breeds, namely Nistari (multivoltine), SK4C (bivoltine) and CSR2 (bivoltine) were designated tolerant, moderately tolerant and susceptible, respectively. To understand the heat shock responses and the molecular mechanisms underlying thermotolerance, the tissue specific expression profiles of the nine heat shock protein (Hsp) genes were determined in the three breeds after a heat shock of 1 h at 36°C and a 2 h recovery period by perform- ing real-time qPCR. The level of expression of Hsp genes was significantly increased in heat shocked tissues and gradually decreased during the recovery period. The greatest increase in the expression of Hsp genes was recorded in fat body followed by mid gut and silk gland. Of the three breeds, Nistari showed the highest expression of Hsp genes and SK4C a moderate expression relative to CSR2. The qPCR results showed that the transcript levels of sHsp20.4 and 20.1, and Hsp70 were increased by 10.3, 9.7 and 2.3 times, respectively, in Nistari compared to CSR2. Similarly the expression of sHsp20.4 and 20.1, and Hsp70 were increased by 3.5, 2.3 and 1.5 times, respectively in SK4C compared to CSR2. The expression levels of Hsps during heat shock corresponded to the percentage pupation recorded for the three breeds at a high temperature. It is suggested that the Hsps and their levels of expression may play an important role in increasing the survival of silkworm larvae at high temperatures. This study identified SK4C as a bivoltine breed, which is highly tolerant of high temperature measured in terms of percentage pupation (of the bivoltine breeds) and higher levels of expression of Hsp genes compared to CSR2. The importance of SK4C as a thermotolerant bivoltine parent for breeding new bivoltine hybrids tolerant of high temperatures is discussed.

Age dependent mate choice influences reproductive and progeny attributes in aphidophagous ladybird beetles (Coleoptera: Coccinellidae)

Despite the many studies on age based mate choice in insects, the question of how age influences mate choice in predaceous ladybird beetles is still unexplored. The present study evaluates age based mate choice in two sympatric aphidophagous ladybirds, Coccinella septempunctata L. and Coccinella transversalis Fab., in terms of mating behaviour (latent period, number of bouts, bout interval and duration of wriggling movements and mating), fecundity, egg viability and the development and survival of their progeny. Results revealed that middle aged (30-40 days) mates were preferred by young (10-15 days post-eclosion), middle aged (30-40 days) and old (45-55 days) individuals of both sexes. Mating behaviour and egg viability differed significantly with male age whereas fecundity, offspring development and survival differed significantly with female age. The shortest latent periods and bout intervals, highest numbers of bouts, longest durations of wriggling movements and mating, and maximum egg viability were recorded for middle aged males whereas fecundity, percentage pupation and adult emergence of offspring were highest and durations of immature development were shortest for middle aged females. Thus, the present study indicates that middle aged individuals of C. septempunctata and C. transversalis are most preferred as mates as they have the highest reproductive output and produce the fittest offspring.

Strategies to Enhance the Toxicity of Bacillus thuringiensis Against Spodoptera littoralis (Boisd.)

Bacillus thuringiensis (Bt) is an aerobic, spore forming bacterium that produces crystal inclusions that contain Insecticidal Crystal Proteins (ICPs) used to control many major pests. ICPs, or Cry proteins, are in the form of protoxins in the crystal. ICPs are solubilized and processed to toxic peptides by gut proteases in insects. Because proteases are important to toxicity, research into interactions of proteases with Bt proteins may lead to improved toxin efficacy. Toxicity of two commercial formulations of Bt was evaluated against 2nd instar larvae of Spodoptera littoralis. Dipel DF was more effective than Dipel 2X (LC50 were 0.13 and 0.17, respectively). In addition, rice bran is an agricultural waste which contains protein, fiber and carbohydrate content. It was tested in the laboratory to determine its stimulatory effects on S. littoralis protease. Adding rice bran extract to commercial formulation of Bacillus thuringiensis var. kurstaki, (Dipel DF) and / or (Dipel 2X) revealed a potential action with Co-toxicity factor +34.33 and + 21.38, respectively indicating good potential for rice bran extract to enhance B. thuringiensis-based formulations. Sodium bicarbonate (NaHCO3), calcium carbonate (CaCO3) and sodium dodecyl sulphate (SDS) were also added to both Dipel DF and Dipel DX. Data showed that all tested bio agents and their mixture with different additives induced significant reduction in both pupation percentage and pupal weight (except in case of NaHCO3). The reduction effect was significantly high in Dipel DF with rice bran extract compared with the control. The pupal malformation ranged from 2.82 to 13.33%. Adult malformation resulted from treated 2nd instar larvae showed also varying degrees of deformities as a side effect of bioinsecticide alone and its combination with additives. The biochemical analysis revealed a significant increase in the proteolytic activity in all treated samples and a significant decrease in the activity of trehalase, invertase and amylase, as compared to control group.

BIOLOGICAL AND HISTOLOGICAL EFFECTS OF METARHIZIUMANISOPLIAE ON THE COTTON LEAFWORM, SPODOPTERA LITTORALIS (BOISD.) (LEPIDOPTERA: NOCTUIDAE)

Toxicological, biological and histological effects of the isolated entomopathogenic fungus Metarhizium anisopliae from the red palm weevil adult on the newly molted 2nd and 4th instar larvae of the Egyptian cotton leaf worm, Spodoptera littoralis (Boisd.), were investigated under laboratory conditions at 27o ± 2o and 60% ± 5% R.H. Results revealed a decrease in the mean larval, pupal, and adult durations for the 2nd and 4th instar larvae surviving treatment with the LC50 of 2.8x108 and 2.8x109 spore/ml for the two tested instar larvae, respectively. Treatment also caused a reduction in the pupation and adult emergence percentage. There was also a great reduction in the mean number of eggs/female and the mean number of hatched eggs; The histological changes in the mid gut tissues in 6th instar surviving treatment with LC50 of M. anisopliae as newly ecdysed 3rd instar larvae was investigated. Sections in mid gut of untreated S. littoralis showed linning with columnar cells surrounded by cross longitudinal muscles fiber, the epithelial cells linning mid gut with its brush border and goblet cells. While, in mid gut of treated S. littoralis some epithelial cells which linning mid gut have lost their brush border, others were completely destructed.

DEVELOPMENT OF SUSCEPTIBILITY OF THE COTTON LEAF WORM, SPODOPTERA LITTORALIS TO NOMOLT COMPOUND IN RELATION TO SOME BIOLOGICAL AND BIOCHEMICAL CHANGES IN THE INSECT BODY

the susceptibility of the 4th instar larvae of the Egyptian cotton leafworm, Spodoptera littoralis (Boisd.) to the chitin synthesis inhibitors, nomolt was evaluated in the laboratory for 10 generations. The fourth instar larvae were treated with various concentrations of nomolt insecticide for 48 hrs in each generation until F10 and LC50s were calculated after 7 days post-treatment in each generation. The obtained results showed that the resistance ratios of the selected generations were increased to 1.2709, 1.2894, 2.3034 and 3.0117 folds, the F3, F6, F8 and F10 generations, respectively. Based on the biological aspect, larval durations were increased significantly in the selected generations compared to the control. Furthermore, the percentage of pupation was reduced in all the treated generations, which being 56.7, 55.0, 43.85, 27.35, 24.66 and 33.56% the adult emergence was significantly affected as it was 82.09, 70.33, 37.71, 55.06, 41.18 and 43.65% in treated F0, F1, F3, F6, F8 and F10 of the selected generations, respectively. The activities of the measured enzymes at 6 days after treatment of the fourth instar larvae showed up and down pattern through the selected ten generations. The activity of α and β esterases as well as protease enzymes was back to normal activity as that of control in the tenth generation meanwhile chitinase enzyme activity remained significantly higher than that of the control.

Sub-lethal effects of Vip3A toxin on survival, development and fecundity of Heliothis virescens and Plutella xylostella.

The assessment of sub-lethal effects is important to interpret the overall insecticide efficacy in controlling insect pest populations. In addition to the lethal effect, sub-lethal effects may also occur in exposed insects. Vegetative insecticidal proteins (Vips) have shown a broad spectrum of insecticidal activity against many insect pest species. In this study the sub-lethal effects of the Bacillus thuringiensis vegetative insecticidal toxin Vip3A on the development and reproduction of Heliothis virescens F. and Plutella xylostella L. were evaluated in the laboratory. The results indicated that the sub-lethal concentration of Vip3A increased the duration of the larval and pupal stages as compared with the control treatment for both species. The percent pupation and percent adult emergence were significantly lower for Vip3A-treated insects. The proportion of pairs that produced eggs and the longevity of adults were not significantly different between treatments. H. virescens and P. xylostella treated with Vip3A showed an 11 and 17% decrease in their intrinsic rate of increase (rm) respectively compared with untreated insects. The results from this study will be helpful to develop the strategy to incorporate Vip 3A containing crops in an integrated pest management programme.

Comparative study to determine food consumption of cotton leafworm, Spodoptera littoralis, on some cotton genotypes

AbstractA study was done on the feeding behaviour, development indices, and biochemical response of 4th instar larvae ofSpodoptera littoralisin which seven cotton genotypes were used: Giza86, Giza88, Giza92, 10229 × Giza 86, H10, Suvin, and Karshenseki. Castor bean leaves were used as the control. All the tested cotton genotypes decreased the feeding behavior ofS. littoralislarvae in terms of consumption percentages, consumption rate (CR), growth rates (GR), efficiency of conversion of ingested and digested food (ECI and ECD), approximate digestibility (AD), and feeding deterrence (FDI) compared to the control. Additionally, all the tested cotton varieties prolonged the time taken for larval and pupal duration and reduced both the pupation percentages and the weight of the resulting pupae, as compared to the control. Giza86 recorded the lowest values of both larval growth index and fitness (7.31 and 1.05, respectively) while the genotype Suvin recorded the lowest standardised growth index (0.020) more than other genotypes and the control that gave 10.16, 1.53, and 0.032, respectively. There was a significant inhibition in the level of both total soluble protein and total lipids, and activities of amylase and the trehalase enzymes in all the tested varieties, compared to that found in the control.

누에 장려품종간 교잡누에의 실용형질 비교

This study was conducted to consider practical use of F2 hybrid and intervariety crossing for the improvement of silkworm eggs export and silkworm eggs manufacture. Now Kumokjam and Baegokjam come into wide use to sericulture farmers but comparison test of F1, F2 hybrid and intervariety have not been done. We weighed against the productivity among economical character. While larval period of F2 among them is most long time, pupation percentage and cocoon yield per 10,000 3rd molted larvae are lower than intervariety. With comparing F2 and intervariety, single cocoon weight of F2 is lower 9 ~ 21% than intervariety, and cocoon shell weight of F2 was lower 10 ~ 18% than intervariety. By number of cocoons per liter, F2 hybrid was lower and more irregular size than intervariety. In coparison with number of egg laid, F2 hybrid Baegokjam was 655 ea (14%) and Kumokjam 625 ea (40%) more than F1 hybrid. Also, F2 hybrid for filament grade went down than F1 hybrid. The advantage of egg production in F2 hybrid can reduce costs because there is no necessity for sex discrimination and germination control. But besides increase of number of egg laid, the productivity including economical characters was greatly lowered. Except for being a lot of laying eggs, cocoon productivity of the F2 was greatly reduced by degeneration of practical traits. Therefore the further studies are needed in order to increase utilization value of the F2 hybrid silkworm.