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1.
Yoshitaka Tsubaki 《Population Ecology》1981,23(1):156-167
The effects of group size on the survival and development of young larvae of Pryeria sinicaMoore were investigated by laboratory and field experiments. Under laboratory conditions, about 20% of isolated larvae died of unsuccessful feeding in the first instar, however, larvae survived successfully in aggregations of four or more individuals. In the field, larvae emerge in early spring and wait for new leaves to open before feeding. In this period, the larger the group size of hatchlings the survival rate became higher. The nest-web spun by hatchlings was considered to play an important role in protecting them from desiccation. In the period that larvae began to feed on leaves, more than 36 larvae are necessary to aggregate for the successful establishment of feeding groups. The nest-web played an important role also in the establishment of feeding group. However, the natural group size of the first instar larvae was larger than the minimum group size to spin a sound nest-web in the field experiment. On the other hand, in later stage, larvae in a large group did not have an excess advantage in survival or developmental rate over larvae in a small group. It was found that the experiments on survival and developmental rates could not explain the reason that this species maintain large compact groups in the most part of larval period. 相似文献
2.
Ishizue Adachi 《Population Ecology》1983,25(1):130-142
Summary Relative abundance of natural food resource, leaves of wild rose, ofArge migrinodosa was evaluated by comparing the food quantity which the larvae composing a colony utilized throughout the larval stage with
that which is available in the habitat. In this connection, behavioral pattern of larval feeding was also observed under natural
conditions, and its ecological significance was discussed.
It was quantitatively clarified that the larvae faced the severe shortage of food and had to disperse to other shoots with
the expense of probably high risk. Under pressures of such insufficient supply of food, the larvae follow the most efficient
pattern of feeding behavior that they move to the tip of shoot at first and feed regularly downward thereafter. Though individual
larvae behaved completely independently of each other, the aggregation appeared to be formed and maintained because all the
larvae from the same egg mass follow this fixed feeding pattern. 相似文献
3.
Kimito Furuta 《Population Ecology》1972,13(2):216-221
The distribution pattern of adults of the large weevil, Hyposipalus gigas on logs of the Japanese black pine and that of larvae in pine stumps were examined by using the m*−m method (Iwao , 1968). The distribution of adults on logs was contagious, probably due to their response to local heterogeneity of the environment. The larval distribution was also contagious, but there was no significant correlation between the number of larval bores and the stump size. The mortality of young larvae seemed not to be related with the number of larvae per stump, but it was related with the density per unit area of bark surface. There was some sign of inversely density-dependent or ‘all-or-none’ type mortaltiy in the late larval stage. 相似文献
4.
Shiro Kobayashi 《Population Ecology》1963,5(2):102-106
To investigate the aggregative nature of the larvae of Pieris rapae crucivora, each 50 individuals of the 4th and 5th instar larvae collected from cabbage farms and reared under crowded and solitary conditions were released on an experimental arena and their dispersive behaviour was observed with the lapse of time. Both the 4th and 5th instar larvae showed the trend to approach toward random distribution when they were released under clumped condition, and they maintained random distribution when they were released at random. Therefore, it may be concluded that the larvae have not any aggregative nature caused by the mutual attraction among individuals. However, as the larvae reared in crowds sometimes showed the slight aggregative behaviour, it seems that the larval dispersal is different between densely and sparsely populated plants in field. 相似文献
5.
CHRISTOPHER DYE 《Ecological Entomology》1982,7(1):39-46
Abstract. 1. Competition within and between the larval instars of the yellow fever mosquito, Aedes aegypti , can be measured by its effect on stage duration. In a series of laboratory experiments the relative importance of chemical interference and food exploitation in mediating competition between first and fourth instar larvae was investigated.
2. In contrast to the results of three previous studies, I found no evidence that a chemical growth retardant played any part in greatly prolonging the stage durations of larvae in both age classes.
3. When competition between the two age classes became important, the relative increase in stage duration wasgreater for first instar larvae than for fourth instar larvae. This result can be reproduced with Gilpin & McClelland's (1979) model of competition by food exploitation alone, providing the range of available food particle size is assumed to be an increasing function of age. An additional, but less important, refinement makes the conversion efficiency of food into larval biomass a decreasing function of age. 相似文献
2. In contrast to the results of three previous studies, I found no evidence that a chemical growth retardant played any part in greatly prolonging the stage durations of larvae in both age classes.
3. When competition between the two age classes became important, the relative increase in stage duration wasgreater for first instar larvae than for fourth instar larvae. This result can be reproduced with Gilpin & McClelland's (1979) model of competition by food exploitation alone, providing the range of available food particle size is assumed to be an increasing function of age. An additional, but less important, refinement makes the conversion efficiency of food into larval biomass a decreasing function of age. 相似文献
6.
Tamotsu Kusano 《Population Ecology》1981,23(2):360-378
Growth and population density of the larvae, Hynobius nebulosus tokyoensisTago , were estimated in a small pond within the study site settled in Habu village of Hinodemachi, a suburb of Tokyo City, during the period from 1975 to 1980. The mortality factors which influenced the survival rate of larvae were also evaluated from the ecological point of view. Laboratory experiments on the growth of larvae and predation by newts were conducted in pararell with the field survey. The results showed that growth rate of larvae under the natural condition was very slow, as compared with that under the laboratory condition with sufficient food supply, and mean body size at metamorphosis was negatively correlated with the density at that time. This suggested that food resources were in short supply in the pond, and there occurred a severe intraspecific competition for food among larvae. The mortality rate of larvae was so high, 80–99% in each year, and the density of larvae survived until metamorphosis varied so greatly from year to year that the larval stage was the most important stage throughout the life cycle to the maintenance of a population for this salamander. The most important factors which contributed to this high mortality were the predation by the newt, Triturus pyrrhogaster pyrrhogasterBoie , and cannibalism. From the laboratory experiment, it was found that predators could attack only small larvae successfully, and successful attack rate decreased sharply as larvae grew larger. This relationship resulted in the characteristic L-shaped pattern of survivorship curve of larvae; that is, heavy mortality just after hatching period. 相似文献
7.
E. D. Fajer 《Oecologia》1989,81(4):514-520
Summary Little is known about the effects of enriched CO2 environments, which are anticipated to exist in the next century, on natural plant-insect herbivore interactions. To begin to understand such effects on insect growth and survival, I reared both early and penultimate instar larvae of the buckeye, Junonia coenia (Lepidoptera: Nymphalidae), on leaves from one of their major hostplants, plantain, Plantago lanceolata (Plantaginaceae), grown in either ambient (350 PPM) or high (700 PPM) CO2 atmospheres. Despite consuming more foliage, early instar larvae experienced reduced growth on high CO2-grown compared to ambient CO2-grown leaves. However, survivorship of early instar larvae was unaffected by the CO2 treatment. Larval weight gain was positively correlated with the nitrogen concentration of the plant material and consumption was negatively correlated with foliar nitrogen concentration, whereas neither larval weight gain nor consumption were significantly correlated with foliar water or allelochemical concentrations. In contrast, penultimate instar larvae had similar growth rates on ambient and high CO2-grown leaves. Significantly higher consumption rates on high CO2-grown plants enabled penultimate instar larvae to obtain similar amounts of nitrogen in both treatments. These larvae grew at similar rates on foliage from the two CO2 treatments, despite a reduced efficiency of conversion of ingested food (ECI) on the low nitrogen, high CO2-grown plants. However, nitrogen utilization efficiencies (NUE) were unaffected by CO2 treatment. Again, for late instar larvae, consumption rates were negatively correlated with foliar nitrogen concentrations, and ECI was also very highly correlated with leaf nitrogen; foliar water or allelochemical concentrations did not affect either of these parameters. Differences in growth responses of early and late instar larvae to lower nitrogen, high-CO2 grown foliage may be due to the inability of early instar larvae to efficiently process the increased flow of food through the gut caused by additional consumption of high CO2 foliage. 相似文献
8.
Minoru Murai 《Population Ecology》1974,16(1):112-126
Summary The greasy cut worm,Agrotis ypsilon
Rott., has a characteristic habit; the larva feeds on the small seedling of the host plant. Studies in a population in outbreak
area suggested that the food shortage temporally took place, causing the reduction of weights of pupae and adults. The fact
that this species depends on the small seedling as the host seemed to be responsible for this food shortage. However, it was
found that the larval crowding also affected the body weight, even if the food was supplied in excess. It was further suggested
that the weight reduction is due to the injury caused by the encounter of larvae.
The oviposition habit to lay small egg masses and the aggressive behaviour of the larva was considered to be responsible for
the uniform distribution at the later larval stage. Probably, the larval dispersion enabled the larva to forage in the most
effective way as well as it protected the larva from the attack of another ones. As a result, this would enable the maximum
number of individuals to survive. It seemed that the functions noted above did not work in the population being under outbreak
condition, because the larval density was unusually high due to mass-invasion of moths. 相似文献
9.
The larvae of Sesamia nonagrioides (Lepidoptera: Noctuidae) grown at 25 degrees C and long photoperiod (16:8h light:dark) pupate in the 5th or 6th (mostly) larval instar, while the larvae reared under a short photoperiod (12:12h) enter diapause during which they consume some food and undergo up to 12 (usually 3-4) stationary larval molts. Diapause programming includes an increase of juvenile hormone (JH) titer in the hemolymph from about 20 to 50 nM in the 4th and 5th instar larvae (titer in earlier instars was not measured). JH I, II, and III are present in approximate ratio 1-2:10:1. The JH titer drops to zero before pupation but remains around 20 nM during diapause. Perfect extra larval molts associated with a body weight increase can be induced in the non-diapausing larvae with a JH analogue (JHA). The weight rise is due to accumulation of reserves and not to a general body growth. The timing of extra molts is similar to the molting pattern of the diapausing larvae only when JHA is present since early larval instars. In the diapausing larvae, JHA application affects neither molting periodicity nor the body weight. It is concluded that (1) Increased JH titer in early larval instars is a part of diapause programming; (2) The extension of larval stage in the diapausing larvae, but not the timing pattern of extra molts, is due to continuously high JH titer; (3) The diapause program includes low food intake, maintenance of a certain body weight, and periodic larval molts. 相似文献
10.
为探明植食性昆虫对受重金属胁迫的寄主植物的生理生态响应机制,本研究用Cd胁迫下银中杨的叶片饲养舞毒蛾幼虫,分析舞毒蛾幼虫对食物的利用情况以及其对Cd的排毒代谢机制.结果表明: 取食Cd胁迫下银中杨的叶片后,舞毒蛾3~6龄幼虫体内的Cd浓度和Cd含量均显著高于对照,但随着幼虫龄期增长,其体内Cd浓度显著降低,而Cd含量有不同程度的提高;舞毒蛾幼虫粪便和虫蜕中的Cd浓度均显著高于对照;舞毒蛾3~5龄幼虫的食物消耗率显著高于对照,而转化率显著低于对照;3~4龄幼虫的食物利用率均与对照差异不显著,但在5龄时显著低于对照.说明在Cd胁迫下,舞毒蛾幼虫能通过有效的排毒代谢途径将体内富集的部分Cd排出体外,且高龄幼虫的排毒代谢能力强于低龄幼虫;舞毒蛾幼虫体质量的增加会对体内的Cd浓度形成一种稀释效应;舞毒蛾幼虫能通过调整食物消耗率和转化率之间的比例,来维持其正常生长发育所需的食物利用率,但超过一定限度后仍会造成食物利用率降低. 相似文献
11.
WANG Shi‐gui YE Gong‐yin HU Cui SHU Qing‐yao XIA Yin‐wu Illimar Altosaar 《Insect Science》2001,8(3):218-226
Abstract The Bt transgenic rice line, i.e. KMD1 containing a synthetic cry 1 Ab gene from Bacillus thuringiensis Berliner was tested in the laboratory for evaluating its effects on larval food consumption, growth and survival of striped stem borer (SSB), Chilo suppressalis (Walker) under different temperatures. The food consumption and body weight growth as well as the survival of both 3rd and 5th instar larvae fed on Bt rice were significantly reduced, as compared with those on the control. The temperature showed no marked effect on both food consumption and body weight growth of larvae fed on Bt rice stems since the onset of 3rd instar, conversely had significant effects as since the initial stage of 5th instar. In contrast, the temperature did not distinctly influence the survival of both 3rd and 5th instar larvae. There was a linearly positive relationship between the corrected mortality of larvae and the accumulative amount of Bt rice tissues ingested by larvae. 相似文献
12.
Simo D. Vasconcelos Jennifer S. Cory Katharine R. Wilson Steven M. Sait Rosemary S. Hails 《Biological Control》1996,7(3):299-306
Quantifying the rate of dispersal of target insects when infected with a disease agent will aid the development of biorational pest control programs. The effect of nucleopolyhedrovirus (NPV) infection on the mobility of second and fourth instarMamestra brassicaelarvae was investigated in the laboratory and field. NPV infection altered larval mobility, with the changes in behavior varying with the timecourse of infection. Diseased larvae moved three to five times further than healthy ones during the middle stages of infection. By the 7th day postinfection diseased larvae were less mobile than healthy counterparts. The same pattern of modified behavior was observed in both instars. Fourth instar larvae moved further than second instars under laboratory and field conditions. In the field, infected larvae tended to die on the apex of the cabbage leaves. Bioassay of the leaves showed a linear decrease in inoculum from central to peripheral plants within the plots, which occurred to the same extent for second and fourth instars. Leaves from plots where infected fourth instar larvae had been introduced had higher inoculum density than those from plots with second instars. 相似文献
13.
Y. Carrière 《Entomologia Experimentalis et Applicata》1992,65(1):11-19
The dispersal behavior of Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae) first instar larvae was studied in the laboratory. The objectives were to investigate the proximal factors influencing larval dispersal and to establish whether a correspondence exists between larval host acceptance and performance. A dispersal bioassay was validated by demonstrating the presence of a positive correlation between larval host acceptance in the laboratory and in the field. Larval age and family origin, as well as host species attributes were shown to influence larval dispersal rates. Seasonal changes in host plants slightly changed the rank order of larval host acceptance. Leaf texture and the availability of refuges on host plants seemed to be important factors influencing the rate of larval dispersal. Plant odor appeared to be used by the larvae to locate leaves. Nitrogen content of plant species corresponded to larval dispersal rates, but the cause of this association is unclear. Larval dispersal did not match host suitabilities as measured by larval performance. The relationship between host preference and suitability in the obliquebanded leafroller is discussed in an ecological and evolutionary perspective. 相似文献
14.
Aleksandar Cingel Jelena Savić Jelica Lazarević Tatjana Ćosić Martin Raspor Ann Smigocki Slavica Ninković 《Insect Science》2017,24(5):768-780
Colorado potato beetle (CPB; Leptinotarsa decemlineata Say, Coleoptera: Chrysomelidae) has shown a remarkable adaptability to a variety of control measures. Although oryzacystatin I and II (OCI and OCII) have potential in controlling pests that use cysteine proteinases for food digestion, expression of a single OC gene in potato exhibited a minimal or no effect on CPB fitness traits. The aim of this study was to examine the effect of coexpressed OCI and OCII in potato (Solanum tuberosum L.) cultivars Desiree, Draga?evka and Jelica on CPB larvae. Growth parameters, consumption rates and food utilization, as well as activity of proteases of CPB larvae were assayed. Second and third instar larvae fed on transformed leaves molted earlier and had higher relative growth and consumption rates than larvae fed on nontransformed leaves, while efficiency of food utilization was unaffected. In contrast, fourth instar maximum weight gain and amount of leaves consumed were about 20% lower for the larvae fed on transgenic potato. Analysis of total protease activity of third instar larvae revealed reduction in overall proteolytic activity measured by azocasein hydrolysis, accompanied with inhibition of cysteine proteinase activity 24 h after ingestion of potato leaves expressing OCI and OCII. However, after long‐term feeding on transformed leaves proteolytic activities of larvae became similar to the controls. Although feeding on OCI/OCII leaves did not affect larval survival, coexpression of OC genes reduced the development time and thus significantly decreased plant damage caused by CPB larvae. 相似文献
15.
Some parasitoids are restricted with respect to the host stage that they attack and even to a certain age within a stage.
In this paper we investigate whether the parasitoidCotesia glomerata can discriminate between old and young caterpillar instars of its host,Pieris brassicae, before contacting these hosts, since contacts with older instars are very risky with a chance of being killed, due to the
aggressive defensive behaviour of the caterpillars.
Flight chamber dual choice tests showed that volatile chemicals emitted by Brussels sprouts plants (Brassica oleracea var. gemmifera) after feeding damage by 1st and 5th larval instars are equally attractive to the wasps. Simulated herbivore damage by 2nd
and 5th larval instars, obtained by treating mechanically damaged leaves with carterpillar regurgitant, was also equally attractive,
even when the wasps were exposed to repeated experience on different larval instars to increase their discriminatory ability.
In contrast, single choice contact bioassays showed that the time spent searching on a leaf with feeding damage of 1st instar
larvae was significantly longer than the time spent on 5th instar feeding damage or on mechanically damaged leaves. Both flight
and contact bioassays did not show any effect of egg-related infochemicals. The results demonstrate thatC. glomerata can discriminate between young and old larval instars ofP. brassicae, without contacting the caterpillars. This is not done through volatile herbivore-induced synomones but through cues that
are contacted after arrival at a caterpillar-infested leaf. 相似文献
16.
Wuchang Zhang Danling Tang Bo Yang Shangwu Gao Jun Sun Zhencheng Tao Song Sun Xiuren Ning 《Hydrobiologia》2009,630(1):257-269
Previous studies which have tested the feeding preferences of shredders for fungal species and the food quality of fungi used
detritus uniformly colonized by a fungus, which is not the case for decaying leaves in streams. It is not known whether shredders
in different development stages exhibit variations in feeding preference and larval performance. This study examined the feeding
preferences and the growth of the third and the fifth instars of Pycnopsyche gentilis larvae using fungal-colonized patches and whole leaves, respectively, having different fungal species compositions (Alatospora acuminata, Anguillospora filiformis, Articulospora tetracladia, Tetrachaetum elegans, and all species combined). The aquatic hyphomycetes used were co-dominant on leaves in the stream inhabited by the caddisfly.
During 14 d of feeding, the larvae of both instars did not show significant differences in feeding preferences for the patches
growing on oak leaves, although the third instar larvae were slightly more selective than the fifth instar larvae. When fed
with maple leaves for 18 d, larval growth rates, gross growth efficiencies, and survivorship were not significantly different
among the fungal treatments. However, the larval growth of both instars fed with fungal-colonized leaves was always significantly
greater than the growth of larvae fed with diets of uncolonized leaves. The third instar larvae grew faster than the fifth
instar larvae, but the growth efficiencies of the two instars were similar. These results suggest that P. gentilis larvae exhibit less selectivity in their feeding than other caddisfly shredders that have been examined and that the dominant
fungi colonizing leaves in their habitat are similar in palatability and food quality for this shredder.
Handling editor: B. Oertli 相似文献
17.
In 1990, natural infestations of the polyphagous vapourer moth, Orgyia antiqua (Lepidoptera: Lymantriidae) in lodgepole pine plantations in northern Scotland, were studied to ascertain the role of host
foraging behaviour on the prevalence of nucleopolyhedrovirus (NPV; Baculoviridae) infection in the population. Aerial dispersal
of early instar larvae (L1–L3) from the tree canopy onto heather foliage at the forest understorey, with subsequent relocation
back onto the tree as late-instar larvae (L4–L6) appeared to play a significant role in the development of a widespread virus
epizootic in which approximately 80% of L4–L6 individuals succumbed to disease. Bioassays of foliage 1 year later showed that
the distribution of NPV followed a pronounced vertical gradient through the forest canopy culminating in high concentrations
of virus in the forest understorey. Experimental systems comprising potted pine trees positioned above heather bases showed
that NPV infections could be acquired by early stage larvae following dispersal from the tree and feeding on the undercanopy
vegetation, then translocated to the tree component for secondary transmission to susceptible tree-feeding individuals. Behavioural
studies indicated that the tendency for first-, second- and third-instar larvae to disperse to the understorey was probably
not influenced by larval density on the tree but was strongly dependent on larval instar. In contrast, the tendency for larvae
to relocate from the understorey heather to the tree was affected by both larval density and larval instar, suggesting that
both these factors may significantly affect virus acquisition, translocation and transmission in the host population. In the
present study, the heather understorey appeared to act as a pathogen reservoir in which virus could persist between host generations.
Spatial heterogeneity in virus distribution combined with host foraging behaviour (dispersal and feeding) resulted in the
pathogen playing a major role in host population dynamics over an extended time period (3 years). The reservoir theory is
supported by the observation that similar dynamics were not observed in O. antiqua populations at neighbouring sites which lacked understorey food plants.
Received: 8 June 1998 / Accepted: 5 October 1998 相似文献
18.
Observations on larval development of Malacosoma neustrium were conducted both in a cork oak stand and in the laboratory by using leaves of different host trees (cork oak, holm oak and downy oak) as food source. Instars were determined using head capsule and frass measurements. In the field the larvae progressed up to the fifth instar before pupating, and the increase in head capsule width followed Dyars Rule with a rate of increase (R.I.) value of 1.74. The same number of instars was determined for the larvae reared with cork oak (R.I. = 1.73) and holm oak (R.I. = 1.70) leaves. The caterpillars reared with downy oak foliage completed larval development in five, six and seven instars and the R.I. values obtained were 1.60, 1.52 and 1.44 respectively. A lower mortality was recorded for the larvae reared on holm oak. Growth and feeding indices were determined for the larvae from the third up to the last instar. The highest leaf consumption was detected for the fifth instar larvae reared on holm oak. For the caterpillars which completed five instars before pupating, the relative consumption rate (RCR) decreased from the third up to the fifth instar: from 4.8 to 1.7 (cork oak), from 7.4 to 3.3 (holm oak) and from 14.3 to 2.1 (downy oak). The relative growth rate (RGR) was highest during the fourth stadium (0.24, 0.27 and 0.33 for larvae reared with cork oak, holm oak and downy oak leaves respectively) and decreased in the fifth instar (0.09, 0.14 and 0.14 for larvae reared with cork oak, holm oak and downy oak leaves respectively), probably because of greater expense of energy due to the approach of maturity. Feeding and growth indices could be useful to define a defoliation prediction model. 相似文献
19.
A.A.I. Ahmed M.Y. Hashem S.M. Mohamed S.H. Shimaa Khalil 《Archives Of Phytopathology And Plant Protection》2013,46(20):2409-2419
The oviposition deterrent effect of water extract of Spodoptera littoralis and Agrotis ipsilon larval frass on Phthorimaea operculella adult females was studied using two types of larval food “Natural host and Semi-artificial diet” under laboratory and storage simulation (semi-field) conditions. Extracted frass of fed larvae on semi-artificial diet showed complete oviposition deterrent effect at treatments with 4th, 5th and 6th instars of S. littoralis, also at treatments with 1st–3rd and 6th instars of A. ipsilon, while the same effect was observed when the larvae fed on castor oil leaves as a natural host only at treatment with frass extract of A. ipsilon 6th instar larvae. Presence of low amounts of phenols and flavonoids in water extract of A. ipsilon larval frass resulted in relatively more effect as oviposition deterrent to fertile adult females on treated oviposition sites, while the opposite effect was obtained in S. littoralis larval frass experiments. At semi-field experiments, the percentage reduction of laid eggs reached 100% after two?days at treatments with frass extracts of 4th and 5th S. littoralis larval instars and A. ipsilon 6th instar larvae fed on semi-artificial diet and/or castor oil leaves. Percentage reduction of laid eggs for untreated sacks reached 93.24 and 48.95% after 2 and 30?days, respectively, when placed between treated sacks, in comparison with the mean number of laid eggs for isolated control. 相似文献
20.
At 25 degrees C and under a long-day photoperiod, all 5th instar Psacothea hilaris larvae pupate at the next molt. Under a short-day photoperiod, in contrast, they undergo one or two additional larval molts and enter diapause; the 7th instar larvae enter diapause without further molt. The changes in hemolymph juvenile hormone (JH III) titers, JH esterase activity, and ecdysteroid titers in pupation-destined, pre-diapause, and diapause-destined larvae were examined. JH titers of the 5th instar pupation-destined larvae decreased continuously from 1.3 ng/ml and became virtually undetectable on day 13, when JH esterase activity peaked. Ecdysteroids exhibited a small peak on day 8, 1 day before gut purge, and a large peak on day 11, 2 days before the larvae became pre-pupae. The two ecdysteroid peaks are suggested to be associated with pupal commitment and pupation, respectively. JH titers of the 5th instar pre-diapause larvae were maintained at approximately 1.5 ng/ml for 5 days and then increased to form a peak (3.3 ng/ml) on day 11. JH esterase activity remained at a low level throughout. Ecdysteroid levels exhibited a large peak of 40 ng/ml on day 18, coincident with the larval molt to the 6th instar. JH titers of the 7th instar diapause-destined larvae peaked at 1.9 ng/ml on day 3, and a level of approximately 1.1 ng/ml was maintained even 30-60 days into the instar, when they were in diapause. Ecdysteroid titers remained approximately 0.02 ng/ml. Diapause induction in this species was suggested to be a consequence of high JH and low ecdysteroid titers. 相似文献