• Journal of Wetlands Research
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• v.15 no.4
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• pp.485-491
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• 2013

This study examined the cannibalistic polyphenism of larval salamander Hynobius leechii by the level of predation risk. Salamander eggs were collected from three regions (Mountain Inwang, Mountain Surak and Gwangju). Eggs were treated by three different risk conditions: (1) high risk, predation risk three times a day; (2) medium risk, predation risk once a day; and (3) low risk, no predation risk. Predation risk was conducted using a chemical cue from Chinese minnows. The chemical cue treatment started from the day of collection and ended one week after hatching. Post-treatment measurements were head width at the level of the eyes (HWE), largest head width (LHW), and Snout-vent length of the each larva. To compare the morphological change according to the predation risk, we modified the two head size, HWE and LHW, to HWE/LHW. A significant difference in HWE/LHW and snout-vent length was evident according to the level of predation risk. And larval mortality was increase by the predation risk. The results indicate that predation risk can cause cannibalistic polyphenism of larval salamander and this morphological change could influence larval mortality.

• Korean journal of applied entomology
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• v.12 no.1
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• pp.1-21
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• 1973

Some experiments were conducted to investigate the effects of the chemosterilant, hempa, on the biology of the rice weevil, Sitophilus oryzae L., and the transmission of the lethal factors in the progeny. One to three days old adult males were fed on the wheat grains treated with concentrations of 0.0625, 0.125, 0.25, and $0.5\%$ of hempa water solution. The effects of the treatment on the mortality, longevity, and the performance of oviposition were examined for the Pl generation, and the hatchability and mortality in the postembryonic development were also tested in the $F_1,\;F_2,\;BC_1,\;F_3,\;and\;BC_2$ generations to analyze the inheritance of the lethal factors. The results obtained were summarized as follows. (1) The average longevity of the treated males were ranged from 26.6 to 30.4 days, and indicated no statistical differences. (2) The mortality of the treated males were ranged between $3.3\%\;and\;13.3\%$ and showed no statistical significance. (3) The overall mean number of eggs laid by a female mated to a treated male with concentrations of 0.0625, 0.125, 0.26 and $0.5\%$ were 3.78, 4.05, 3.75 and 3.61 for the respective treatments, and they were not differ significantly from those of control which were 3.60 per female per 3 day period. The unmated female laid 1.91 in the same period, and significantly differ from those in other experimental groups. (4) The overall mean hatchability of the eggs laid by the females mated with males that had been treated with various concentrations of hempa were 86.82, 64.77, 53.47, 40.33 and $24.78\%$ for the respective concentrations of 0, 0.0625, 0.125, 0.25 and $0.5\%$. The hatchability decreased with the increasing concentrations. (5) The minimum hatchabilities were obtained from the eggs laid in the period of 10-12 days after treatment, then the hatchability increased showing some recovery. The recovery seemed to be very much delayed for the males which had been treated with the greater concentrations. Such a difference in hatchability might be related with the sensitivity of the developmental stages of the sperms, and broader spectrum in the stages and severer effects seemed to be associated with the increased concentrations. (6) The overall mean of larval mortality in the $F_l$ generation were 6.55, 17.89, 27.40, 35.42 and $52.17\%$ for the respective concentrations of 0,0.0625, 0.125,0.25 and $0.5\%$. And there was a tendency to increase in the mortality with the increase of concentrations. (7) The correlation coefficients between per cent sterile eggs and larval mortality for the experimental plots of 0.125, 0.25 and $0.5\%$ treatments showed r=+0.83 and +0.85, respectively, and it seemed to be close correlation between the lethal effects on the embryonic and post-embryonic developments. (8) Since the $SC_{50}$ of the sterile eggs was $0.133\%$ and $SC_{50}$ of the larval mortality was $0.565\%$, it was considered that tile lethal factors expressed more in the egg stages than the larval stages. (9) The ratio of female to male in the $F_l$ adults showed 100 : 125, 100 : 108 and 100 : 124 for the plots of 0.125, 0.25 and $0.5\%$ treatments, respectively. And it n·as considered that the sex ratio distortions might occur with the higher concentrations. (10) When the F, males originated 1.on the eggs had been laid by p, in the period of 16-18 days after treatment, were crossed to normal females $(BC_1)$ and made sib matings $(F_2)$, the per cent sterile eggs of the $BC_1$ generation were 13.88 and $33.04\%$ , and were 31.01 and $38.73\%$ for the $F_2$generation with the plots of 0.0625 and $0.125\%$ treatment, respectively. And these seemed to be a results of the $F_1$ individuals are carrying some chromosomal aberrations (11) The larval mortality was the highest in the $F_2$ plot and followed the female backcross plot, and the least in the male backcrosses. (12) The proportions of 1st and 2nd instar larvae among the larval development at tile 17th day after oviposition were 10.98, 27.26, 32.98 and $15.73\%$ in the normal female $\times$ normal male, $F_1$ female$\times$normal male, normal $female \;\times F_1$ male and $female \;\times F_1$ male plots, respectively. It was considered that the larval development might be delayed by the treatment in the 2nd generation. (13) Per cent larval mortality and sterile eggs were greater in the $F_2$ sib mating plots $(F_3)$ than both of $F_2$ backcrosses. Therefore, it seemed that some of the recessive lethal mutations might affect in the further generations. (14) The sterility, induced by the treatment of chemosterilant, hempa, was considered as the result of the dominant lethal mutations due to chromosomal aberrations such as translocation and/or deletion. The effects of these lethal factors seemed to be inherited tip to 3rd generation after treatment.

• Ocean and Polar Research
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• v.37 no.1
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• pp.37-47
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• 2015

The effects of low salinity (fertilization success and larval survival) on the limpet Cellana grata were studied at early stages of development using the marine bioassay technique. It was shown that, under normal conditions for development from fertilization to the post veliger stage, the salinity must be not less than 20.0~35.0 psu. However, the fertilization rate and larval survival of C. grata was obviously reduced at 5.0 psu and 10.0 psu, respectively. Mass mortality was estimated to occur at <20.0 psu (48-h $EC_{50}=19.54psu$) and the survival rate of normal veliger larvae decreased with experimental time during exposure. No observed effective concentration (NOEC) and lowest observed effect concentration (LOEC) of post veliger were estimated at 30.0 psu and 25.0 psu, respectively, during 48-h exposure. The tolerance limits of the test species to salinity revealed various concentration ranges of salinity, which may reflect the physiology and ecology of the initial development stages of C. grata. These results demonstrate that reduced salinity is detrimental to the reproductive success and larval survival of C. grata, and if salinity is lowered by natural or anthropogenic sources during spawning, this would lead to decreased reproductive success and larval settlement.

• International Journal of Industrial Entomology and Biomaterials
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• v.27 no.2
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• pp.243-264
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• 2013

Antheraea mylitta Drury is a commercial silk producing forest insect in India and Xanthopimpla pedator Fabricius is its larval-pupal endoparasitoid, which causes pupal mortality that affects seed production. Effects of host plants, rearing season and their interactions on parasitic behaviour of X. pedator were studied here, as influence of these factors on biological success of X. pedator is not known. Seven forest tree species were tested as food plants for A. mylitta, and rate of pupal parasitization in both the rearing seasons were recorded and analysed. Results showed that rearing season and host plants significantly affected the rate of pupal parasitization in both the sexes. Pupal mortality was found significantly higher (14.52%) in second rearing season than the first (2.89%). Likewise, host plants and rearing seasons significantly affected length, diameter, and shell thickness of cocoons in both sexes. Out of all infested pupae, 85.59% were found male, which indicated that X. pedator chooses male spinning larva of A. mylitta for oviposition, but we could not answer satisfactorily the why and how aspect of this sex specific parasitic behaviour of X. pedator. Multiple regression analysis indicated that length and shell thickness of male cocoons are potential predictors for pupal parasitization rate of X. pedator. Based on highest cocoon productivity and lowest pupal mortality, Terminalia alata, T. tomentosa, and T. arjuna were found to be the most suitable host plants for forest based commercial rearing of A. mylitta in tropical forest areas of Uttarakhand state, where it has never been reared earlier. Sex and season specific interaction of X. pedator with its larval-pupal host, A. mylitta is a novel entomological study to find out explanations for some of the unresolved research questions on parasitic behaviour of X. predator that opens a new area for specialised study on male specific parasitization in Ichneumonidae.

• Journal of Sericultural and Entomological Science
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• v.16 no.1
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• pp.93-100
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• 1974

It is reported that the useful larval characteristics and cocoon quality is damaged when the silkworm is fed on the insecticides contaminated mulberry leaf. The results obtained are as follow： 1) Mortality is growing when the silkworm is fed with the leaf treated with 1,000 folds insecticides and left for 25 days. 2) There are differences in the effects on the useful larval characteristics according to the insecticides, 3) Hernial larvae are brought about when the silkworm is fed with lebaycid stained leaf. 4) Malformed cocoon and abnormal silk is caused by the insecticide stained leaf feeding.

• The Korean Journal of Ecology
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• v.15 no.3
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• pp.257-265
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• 1992

The effects of insecticide dimilin including the technical grade(tg) and wettable power(wp-25), inhibiting the synthesis of chitin in the cuticle of insect larvae, and herbicides alachlor and atrazine on the development of shrimp caridina denticulata denticulata were investigated in various concentrations. This species is abundant in the freshwater such as river and pond. The shrimp larvae were reared at dimilin solutions(tg and wp 2), alachlor solutions, and atrazin solutions. the concentrations of dimiline were 0, 1, 5, 10 and 25 ppb dimilin solutions, and those of alachlor and atrazin were 0, 1, 5, 10 and 25ppm, respectively.mortality was high at 10 ppb when the larvae were exposed to dimilin and at 25ppm in the case of alachlor and atranzine solutions. If lethal concentration is defined as a concentration in which less than 10% of larvae to the post larval stage from hatching it can be concluded that the lethal concentration of dimilin is 5ppb, and that of alachlor and atrazin is 25 ppm.

• Korean journal of applied entomology
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• v.36 no.1
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• pp.48-54
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• 1997

This study was conducted to determine the effect of temperatures and food sources on the egg and larval developmentof the tobacco cutworm, Spodoptera litura Fabricius. The hatchability of egg masses of S. liturawas 100% on the leaf of soybean, perilla and sweet potato in any given temperature regimes, while the hatchabilitywas only 65-8796 when reared on the pulp paper and decreased as temperature increased. Egg durationwas not significantly different among different food sources within each temperature. However, egg duration at32$^{\circ}$C was shorter than that at 24$^{\circ}$C and 28$^{\circ}$C. During the early larval development, at 28$^{\circ}$C and 32$^{\circ}$C the larvafed on sweet potato leaf was heavier than those fed on soybean and perilla leaves and the opposite case wastrue during mid-larval development stage. However, larval weight at 24$^{\circ}$C was heavier on sweet potato leafthan that on soybean and perilla leaves until 12 days after hatching. This result was probably due to relativelyslower developmental rate at 24$^{\circ}$C compared to 28$^{\circ}$C and 32$^{\circ}$C. The mean larval mortality was 68.896, 44.5%and 33.8% at 24$^{\circ}$C. 28$^{\circ}$C and 32"C, respectively. The lowest mortality was observed on soybena leaf and followedby perilla and sweet potato leaves, and artificial diet regardless of temperature conditions. The durationwas the shortest when they fed on soybean leaf, and followed by perilla and sweet potato leaves and artificialdiet. Larval durations were 23.6-30.4 days at 24$^{\circ}$C. 18.6-22.3 days at 28$^{\circ}$C and 14.5-18.0 days at 32$^{\circ}$C. Thethreshold temperatures of egg and larva of S. litura were about 6.l"C and 10.9"C, respectively.t 6.l"C and 10.9"C, respectively.pectively.

• Asian Journal of Turfgrass Science
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• v.19 no.1
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• pp.17-25
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• 2005

Pathogenicity of entomopathogenic nematde, Steinernema carpocapsae Pocheon strain (ScP) was evaluated against different larval stages(2nd, 3-4th and 5th) of Anomis commode and Anomis mesogona(Lepidoptera: Noctuidae) in petri dish and pot. The $LC_{50}$ values were increased in proportion to larval stage of A. commoda and A. mesogona. $LC_{50}$ value of ScP against 2nd instar of A. commoda and A. mesogona was 9.7 and 4.5, respectively. The 2nd instar of both species was also susceptible to ScP in pot test. That is, mortality of 2nd instar of A. commode and A. mesogona was higher representing $72.5\%\;and\;87.5\%$ 5 days later after treatment, respectively, when ScP was applied at the ,ate of 90,000 infective juveniles(Ijs) per $pot(=1\times10^9\;Ijs/ha)$. However, susceptibility was decreased from 3rd instar. Mortality of 5th instar of A. commoda and A. mesogona was $5.0\%\;and\;10.0\%$, respectively, at the rate of 90,000 Ijs/pot. When ScP was applied into pot including mixed larval stages from 2nd to 5th instar(10 larvae far 2nd instar, 10 larvae for 3rd - 4th instars, and 10 larvae for 5th instar) at the rate of 90,000 Ijs/pot, mortality of A. commoda and A. mesogona was $69.2\%\;and\;50.0\%$, respectively.

• Korean Journal of Environmental Agriculture
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• v.35 no.4
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• pp.241-246
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• 2016

BACKGROUND: Recently, the widespread distribution of pesticides in the hive has been of concern about pesticide exposure on honeybee (Apis mellifera L.) health. Larval toxicity was adapted to assess the synergistic and antagonistic interaction of cumulative mortality to the honeybee larvae of the four most common pesticides detected in pollen. METHODS AND RESULTS: Acetamiprid($3.0{\mu}l/L$), chlorothalonil ($803.0{\mu}l/L$), coumaphos ($128.0{\mu}l/L$), and tau-fluvalinate ($123.0{\mu}l/L$) were tested in combination; binary, ternary and four component mixture. Larvae were exposed to four pesticides mixed in diet at the average levels detected in pollen. As a result, synthetic toxicity was observed in the binary mixture of acetamiprid with coumaphos. The binary and ternary component mixtures of tested pesticides have mostly demonstrated additive effect in larval bees. The significant antagonistic effects were found in four parings of mixtures including chlorothalonil added to acetamiprid/tau-fluvalinate or acetamiprid/coumaphos/tau-fluvalinate, and tau-fluvalinate added to acetamiprid/chlorothalonil or acetamiprid/coumaphos/chlorothalonil. CONCLUSION: Interactions between combinations of four pesticides showed mostly additive or antagonistic effects in larval bees. Therefore, predicting the larval mortality of pesticides mixtures on the basis of the results of single pesticide may actually overestimate the risk. We suggest that pesticide mixture in pollen be evaluated by adding their toxicity together for complete data on interactions.

• International Journal of Industrial Entomology and Biomaterials
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• v.40 no.2
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• pp.41-50
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• 2020

Vermicompost, manure, compost and organic fertilization are ecofriendly. Nowadays, many products resulted from sericulture consumed by humans such as mulberry leaves, fruits, mulberry tea, silk and natural silk cosmetics. Soil applications of three treatments with vermicompost (0.5, 1 and 2 tons per 0.42 hectare) and recommended rate of mineral fertilizers of nitrogen phosphorus potassium were used for investigation. Impact of fertilization on mulberry plant traits of moisture, number of shoots/tree, total shoots length/tree, number of leaves/shoot, number of leaves/ (100g), leaf yield/tree and leaf yield of fadden/season were recorded. In addition the effect of fertilization on larval and cocoon characters of young instar duration, fifth instar duration, total larval duration, larval mortality percentage, weight of third instar larvae, weight of fourth instar larvae, weight of fifth instar larvae, fresh cocoon weight, fresh shell weight, pupae weight, cocoon shell ratio, silk productivity, cocooning percentage, pupation ratio, number of cocoons/ liter, crop cocoons by number, crop cocoons by weight, fecundity and fertility. Using vermicompost treatment was enhancing plant characters. Treatments of V₃, V₂ and V₁ were shortage young, fifth and larvae durations. Mostly feeding silkworm during the whole larval duration on treated mulberry leaves with vermicompost improving the traits average. Using vermicompost for fertilization by rate of V₃ and V₂ is better than others for cocoon characters for females and males.V₃ and V₂ of vermicompost per 0.42 hectare is recommended for rearing mulberry silkworm instead of mineral fertilization.