A sampling plan for population dynamics studies on currant clearwing,Synanthedon tipuliformis (Lepidoptera: Sesiidae)

Abstract

Sampling techniques for eggs, larvae, and pupae of the currant clearwing, Synanthedon tipuliformis (Clerck), attacking blackcurrant were developed, and their precision was evaluated. Reliable population estimates for the egg and early larval stages (standard error < 10%) were obtained by sampling one cane with at least two age groups of wood from the north and south halves of seven bushes in nine blocks. Similar precision was obtained for post-winter larvae from samples comprising three canes from each half of the bushes, but using this sampling scheme a lower precision (S.E.?25–30%) had to be accepted for overwintering mortality factors. The pupal population was estimated from the numbers of live larvae at the end of the post-winter feeding stage, and cross-checked from the number of emergence holes in the 1-year-old wood taken for egg sampling the following year. This procedure gave estimates of similar reliability to those for the egg and larval stages.     

The distribution and dispersion of life stages of currant clearwing,Synanthedon tipuliformis (Lepidoptera: Sesiidae), in blackcurrant

Abstract

The distribution of life stages of currant clearwing, Synanthedon tipuliformis (Clerck), in blackcurrant bushes was investigated on two plots during 1971–75. Three ways of expressing the distribution are examined, none of which is totally acceptable. Generally less than 10% of eggs are found on the current season's growth, and since wood of this age group represents over 50% of the available universe, the proportion of eggs laid on it is relatively low. The proportion of the larval population in the younger wood increases until just before pupation, when over 80% of the population is in the most recent 2 years' growth. The 1-year-old wood harbours 50% of the early larval population, and a use for this information in assessments of the effectiveness of insecticide trials against adults is suggested. The dispersion of eggs and larvae of S. tipuliformis is shown by a number of indices to be aggregated. The frequency distribution is adequately described by the negative binomial. A common k, k _c, of 0.66 (95% confidence limits 0.57–0.80) for the egg stage was valid, but the k _c for the larval stage of 1.28 (1.09–1.56) was only marginally valid.     

Life tables of currant clearwing,Synanthedon tipuliformis (Lepidoptera: Sesiidae), in blackcurrant in Canterbury

Abstract

Survivorship curves and life tables for the 1971-75 generations of currant clearwing in an unsprayed blackcurrant (cv. 'Cotswold Cross') plantation and for the 1972-74 generations in a sprayed blackcurrant plantation (cvs 'Cotswold Cross' and 'Magnus') are presented. The key element in the life cycle is identified as adult survival, and the density dependence of the various mortalities is identified by various indices. The possible effects on population levels of currant clearwing of the proposed pruning management for mechanically harvested blackcurrants is discussed.     

苍耳杆野螟生物学特性的研究

苍耳杆野螟是寄生在苍耳上的1种重要药用昆虫。在湖南（常德）每年发生4代,以老熟幼虫（五龄）在苍耳茎杆蛀道内越冬。室内自然变温下（22．2～25．0℃）饲养,卵期为4．8天,幼虫期为23．6天,蛹期为见11．8天,成虫期为6．1天。每雌可产卵124～585粒,块产。一、二龄幼虫食叶,三龄后蛀茎。     

The effect of soil depth and exposure to winter conditions on survival of the potato tuberworm,Phthorimaea operculella

The potato tuberworm, Phthorimaea operculella Zeller (Lepidoptera: Gelechiidae), is an important pest of solanaceous crops including potato [Solanum tuberosum L. (Solanaceae)]. Recent evidence of survival of the pest in the Columbia Basin of Oregon and Washington, USA, is surprising as potato tuberworm is most commonly a pest in tropical and subtropical regions. Potato tuberworm was studied in a manipulative experiment to determine how stage (egg, larva, and pupa) and soil depth affected the potential for winter survival. In early January 2007, eggs, tubers infested with larvae, and pupae were placed in the soil at 6, 10, and 20 cm depths, or left on the soil surface. Each potato tuberworm life stage was sampled at 7–17‐day intervals for 90 days and survival was estimated at each time period. Eggs survived up to 54 days with the greatest survival observed at 6‐cm soil depth and the lowest survival on the soil surface. However, egg survival was significantly reduced after 1 month of exposure to winter conditions. Larvae were able to survive up to 30 days with the greatest survival observed at 20‐cm soil depth. Tubers at the surface and buried at 6 cm were frozen; thus, no larval survival was recorded. The pupal stage showed a greater tolerance to winter conditions than the egg or larval stages, surviving up to 91 days of exposure. These results suggest that the pupal stage is probably the stage most likely to survive winter conditions in the northwestern USA.     

New larval agar-based diet for laboratory rearing of Mediterranean fruit fly <Emphasis Type="Italic">Ceratitis capitata</Emphasis> (Diptera,Tephritidae)

Five larval diets for laboratory rearing of Ceratitis capitata were tested. These diets were based on wheat bran, microcellulose, potato starch and agar. To evaluate the quality of diet, pupal rearing efficacy and pupal weight were checked. The best results were obtained with an agar based diet used for Manduca sexta laboratory rearing. To simplify the preparation and to reduce the cost of this diet, a new formulation was developed. Larvae reared on the new agar-based diet achieved higher pupal rearing efficacy than larvae reared on bran diet recently used in medfly mass rearing facilities. Heat treated medflies reared on the new agar-based diet achieved similar pupal rearing efficacy with heat treated medflies reared on bran diet. When testing population density, higher pupal rearing efficacy was again achieved on new diet. The highest pupal rearing efficacy was achieved with 100 eggs per 25 g of diet, lowest with 500 eggs per 25 g of diet. Concerning pupal weight, there was no difference in results achieved on Petri dishes with different larval population densities. Larvae reared on new agar-based diet reached better results than larvae reared on bran diet. The preparation of the new diet is simple and the cost is low, so it is good for laboratory tests and rearing.     

Natural mortality of currant clearwing,Synanthedon salmachus (Lepidoptera: Sesiidae), in New Zealand

Abstract

In a wide-ranging survey of 11 blackcurrant blocks, mortality of currant clearwing, Synanthedon salmachus (L.), was found to range from 1.3% to 9.7% for larvae and from 5.3% to 23.0% for pupae. At least 51% of the mortality was caused by the fungal pathogens Beauveria bassiana, Paecilomyces farinosus, and Verticillium lecanii. One unidentified predatory carabid larvae was collected, and two parasites—Xanthocryptus novozealandicus and Diadegma sp.—were reared from clearwing larvae.     

Interaction between relative humidity and resistance to Dasineura tetensi in blackcurrant

1 Infestation by the blackcurrant leaf midge Dasineura tetensi and galling incidence on a susceptible (cv. ‘Öjebyn’) and a moderately resistant (cv. ‘Storklas’) blackcurrant genotype was studied in the field for two midge generations in the same growing season. On the resistant genotype gall initiation is delayed. 2 The relation between infestation and galling incidence showed considerable variation between the two generations. Galling symptoms produced by the second midge generation were weak on the resistant as compared with the susceptible blackcurrant. 3 Because larval development of that generation coincided with a period of dry and warm weather, it is possible that larvae on the resistant genotype suffered desiccation to a greater extent than larvae on the susceptible genotype where gall development was stronger. 4 The possible interaction of relative humidity and expression of resistance was investigated in controlled environment experiments. The resistant ‘Storklas’ and a susceptible (‘7801–31’) currant genotype were studied at two constant relative humidities, 30 and 70%. 5 Larvae of D. tetensi suffered from higher mortality and reduced growth rate on both genotypes in the low humidity environment. 6 There was also a significant plant genotype by humidity interaction on larval performance; no galls were produced and no larvae completed development on the resistant currant at low humidity. 7 There was a trend for a positive correlation between larval length and larval density on a plant at low humidity but not at high humidity.     

Aseptic rearing of Epiphyas postvittana (Lepidoptera: Tortricidae) on a meridic diet

The light brown apple moth, Epiphyas postvittana (Walker), was reared aseptically from newly hatched larvae to adults for three generations on a meridic diet. Growth and development on this diet were comparable with that on oligidic diets and on host‐plants. At 25 ± 1°C, 50–60% R.H., and 12‐h photophase, the average larval period was approx. 28 days, pre‐pupal and pupal 11–12 days, and pre‐oviposition approx. 2 days; the incuva‐tion period of eggs was approx. 7 days. The average developmental period from egg to adult was thus about 49 days; 89 % of larvae reached the adult stage. The average fecundity was 598 eggs per female, and the sex ratio was nearly 1:1. There were no differences in the rate of development or in fecundity of insects reared on media with and without a mould inhibitor.     

The effects of temperature on development of the large narcissus fly (Merodon equestris)

Eggs, larvae, pupae and adults of the large narcissus fly (Merodon equestris) were reared at a series of constant temperatures between 9–24°C. Egg development required from 37 days at 9°C to 7 days at 21.5°C. The low-temperature threshold for development was 6.7°C. Larvae reared at 1424°C were fully-grown after 18 weeks, but it took much longer for such insects to pupate, and adult flies emerged only after about 45 weeks of development. Large narcissus flies enter diapause during the larval stage and overwinter as fully-fed larvae, forming pupae in the following spring. Post-winter pupation and pupal development took from 169 days at 10°C to 36 days at 21.5°C. Of this, pupal development required from 91 days at 10°C to 19 days at 21.5°C. The low-temperature threshold for post-winter pupation and pupal development was 7.1°C, and for pupal development alone, 7.2°C. Females maintained at or below 19°C laid few eggs, whereas some females kept at or above 21.5°C laid more than 100 eggs (mean 69 ± 36). Approximately 50% of females maintained at or above 21.5°C laid less than 10 eggs during their lifetime. The mean egg-laying time was 6 to 9 days. Although temperatures at or below 19°C inhibited mating, once a female had mated, such temperatures did not prevent oviposition.     

蔗扁蛾生物学特性及幼虫耐寒性初步研究

蔗扁蛾在江苏地区目前已发现 5个科、8种寄主 ;在扬州 1年发生 4代 ,以幼虫越冬 ;2 5℃下 ,利用寄主发财树饲养该虫 ,卵历期为 5 7d ,幼虫期为 3 4 4d ,蛹历期为 1 4 9d ,整个世代历期为 5 7 6d;不同季节高龄幼虫的过冷却点不同 ,分别为 :冬前 -4 3 6℃ ,隆冬 -6 44℃ ,冬后 -4 89℃ ;不同低温对蔗扁蛾幼虫死亡率影响很大 ,-2℃幼虫 72h后大都死亡 ,-5℃幼虫 48h全部死亡 ;在扬州地区 ,蔗扁蛾在室外安全越冬的可能性较小     

Life history and host range of Alagoasa extrema (Coleoptera: Chrysomelidae: Alticinae), a potential biological control agent of Lantana spp. (Verbenaceae) in Australia

The life history and host range of the lantana beetle, Alagoasa extrema, a potential biocontrol agent for Lantana spp. were investigated in a quarantine unit at the Alan Fletcher Research Station, Brisbane, Australia. Adults feed on leaves and females lay batches of about 17 eggs on the soil surface around the stems of plants. The eggs take 16 days to hatch and newly emerged larvae move up the stem to feed on young leaves. Larvae feed for about 23 days and there are three instars. There is a prepupal non-feeding stage that lasts about 12 days and the pupal stage, which occurs in a cocoon in the soil, lasts 16 days. Teneral adults remain in the cocoon for 3 days to harden prior to emergence. Males live for about 151 days while females live for about 127 days. The pre-oviposition period is 19 days. In no-choice larval feeding trials, nine plant species, representing three families, supported development to adult. Three species, Aloysia triphylla, Citharexylum spinosum and Pandorea pandorana were able to support at least two successive generations. These results confirm those reported in South Africa and suggest that A. extrema is not sufficiently specific for release in Australia. Furthermore, it is not recommended for release in any other country which is considering biological control of lantana.     

Genome‐wide microarray screening for Bombyx mori genes related to transmitting the determination outcome of whether to produce diapause or nondiapause eggs

The bivoltine silkworm Bombyx mori (Lepidoptera: Bombycidae) exhibits a maternally controlled embryonic diapause. Maternal silkworms decide whether to lay diapause or nondiapause eggs depending on environmental factors such as the temperature and photoperiod during the egg and larval stages, and then induce diapause eggs during the pupal stage. However, little is known about the molecular mechanism that conveys the outcome of whether to produce diapause or nondiapause eggs from the egg or larval stages to the pupal stage. This study used microarray analysis to investigate differentially expressed genes in the larval brains of diapause‐ and nondiapause‐egg producers, to which bivoltine silkworms were destined by thermal or photic stimulation during the egg stage. The cytochrome P450 18a1 and Krüppel homolog 1 genes were upregulated in producers of diapause eggs compared with those of nondiapause eggs under both experimental conditions. Cytochrome P450 18a1 encodes a key enzyme for steroid hormone inactivation and Krüppel homolog 1 is an early juvenile hormone‐inducible gene that mediates the repression of metamorphosis. The upregulation of these genes during the larval stage might be involved in the signaling pathway that transmits information about the diapause program from the egg stage to the pupal stage in the silkworm.     

Maintenance of the phenology of the winter moth (Lepidoptera: Geometridae)

Adult winter moths ( Operophtera brumata (L.)) are active in late autumn or early winter. The eggs overwinter in the canopy of trees and hatch simultaneously with the bursting of host tree buds. Many young larvae disperse on the wind on silk strands. Larvae are polyphagus and feed until late spring when they pupate in soil or leaf litter. The duration of the egg and pupal stages is genetically determined and varies with latitude. The egg stage is long in the north and short in the south, while the pupal stage is short in the north and long in the south.
The literature on the ecology and physiology of winter moth is reviewed. The factors maintaining the unusual phenology are discussed. It is concluded that the larval stage is early because mature leaves of many host trees are unsuitable as food, because parasitism against later larvae is more intense, and because summer temperatures may be injurious to larvae. The adult period is late in the year so that the final stages of pupal development occur in cool conditions and so that adults emerge after most insect predators have ceased activity. Throughout most of the range retarding the adult emergence period would cause activity to be impeded by severe winter weather; in the south this is not so and it is suggested that eggs must be on the trees for a minimum period to ensure synchronization of egg hatch with bud burst. The protracted adult emergence period may be an adaptation reducing predation by birds.     

Development ofDiatraea Saccharalis [Lep.: Pyralidae] at constant temperatures

At constant temperatures between 15.6 and 32°C the incubation time of eggs ofDiatraea saccharalis (F.) was reduced by each increase in temperature. At 34°C the time decreased. Highest (98.6%) and lowest (9.9%) egg hatch occurred at 26 and 34°C, respectively. Larvae completed development at temperatures ranging from 22 to 34°C; however, only 4.4% of the larvae pupated at 34°C. Duration of the larval stage at 30°C (♂=18.1 days; ♀=19.1 days) was ca. 14 days shorter than at 22°C. Maximum rate of development in the pupal stage occurred at 28°C (ca. 6.8 days), and a higher temperature increased developmental time and mortality. Adult longevity and egg production generally were reduced with increasing temperatures and egg production was highest at 24°C (729.8 eggs/ moth). As many as 7 larval stages occurred; but most larvae completed development in 5 stages, and none completed development in less than 5 stages. The female larval stage was ca. 1 day longer than that of males, and this difference occurred primarily in the 5th stage.     

Seasonal plasticity in growth and development of the speckled wood butterfly, Pararge aegeria (Satyrinae)

Regulation of growth and development by photoperiod was studied in a population of the speckled wood butterfly, Purarge aegeria L. (Lepidoptera: Satyrinae), from southern Sweden. Individuals were reared in a range of photoperiodic regimes (9L. to 22L) and temperatures (13°C to 21° C). Plasticity was found for important life-history traits- generation time, growth rate and final weight and seasonal regulation of development in response to photoperiod was found to occur at two levels. Purarge aegeria hibernates as a third instar larva or in the pupal stage, cantering one of four major developmental pathways in response to photoperiod: (1) direct development in both the larval and pupal stages, (2) pupal winter diapause with or (3) without a preceding larval summer diapause, or (4) larval winter diapause. In addition to this high-level regulation of individual development, larval growth rate and pupal development rate also appear to be finally regulated by photoperiod within each major pathway. As photoperiods decreased from 22 h to 17 h at 17° C, growth rate among directly developing larvae increased progressively, as was the case for larva? developing according to a univoltine life cycle from 17 h to 14 h. At two photoperiods, 13 h and 16 h (corresponding to shifts between major pathways), both larval and pupal development were extremely variable with the fastest individuals developing directly and the slowest developing with a diapause. This indicates a gradual nature of diapause itself, suggesting that the two level may not he fundamentally different.     

Correlated responses to selection for developmental rate inTribolium

Selection for fast and slow development in flour beetlesTribolium castaneum (CS) andT. confusum (CF) has resulted in a number of correlated responses in other characters. In general, the fast selected lines of both species have responded similarly with respect to these other traits. The fast lines are characterized by decreased length of time spent in all juvenile stages, decreased size, and essentially the same productivity and hatchability of eggs as the synthetic stocks. In CS-fast there was a substantial decrease in larval survival and an increase in the frequency of abnormal adults. The latter observations did not hold for the CF-fast line.The CS-slow line, on the other hand, exhibited an increased duration of egg, larval and pupal stages, increased size (at least as determined by pupal weight), and decreased hatchability and larval survival. Productivity also decreased somewhat when measured as the number of eggs per female per day. The frequency of abnormal beetles was also higher in this line than in the foundation stock.Fitness, as measured by competitive ability, decreased in all selected lines, supporting the notion of an intermediate optimum for developmental rate in the foundation populations.No evidence was found to support the existence of a compensation mechanism for developmental rate such as that found inDrosophila, whereby faster larval development is compensated for by an increase in the length of the pupal stage.     

Seasonal phenology and stage-specific parasitism of the apple ermine moth, Yponomeuta malinellus Zeller, in Korea

The apple ermine moth, Yponomeuta malinellus Zeller (Lepidoptera: Yponomeutidae), is a tent caterpillar that feeds on Malus spp. in Korea. Populations of the moth in native areas appeared to be regulated by the assemblage of parasitoids. Phenological associations between host stages and parasitoids, susceptible stage(s) of the host for each parasitoid, and stage‐specific parasitism were studied. The egg larval parasitoid Ageniaspis fuscicollis (Dalman) had highest parasitism of first instar larvae (24%), with 14% parasitism of other larval stages. Dolichogenidea delecta (Haliday) was recovered from all larval instars with the highest parasitism rate of second instar larvae (20.1%), followed by 19.9% parasitism of mid‐larval hosts. Herpestomus brunicornis Gravenhorst was reared from second instar larvae through to pupal collection, and had the highest parasitism rate (29.9%) at the pupal stage. The larval pupal parasitoid Zenillia dolosa (Meigen) was recovered from mid‐larval to pupal stages with the highest parasitism rate (5.5%) occurring in third to fourth instar larvae. The host stages for developing A. fuscicollis completely overlap with those of D. delecta, and with those of H. brunicornis to some degree. A statistically significant negative correlation exists between A. fuscicollis and these dominant parasitoids, indicating competitive interaction within the host.     

条纹小斑蛾的生物学特性

条纹小斑蛾Thyrassia penangae(Moor)是乌蔹莓(Japanese cayratia)的重要害虫,在南昌1年发生4～5代,以老熟幼虫结茧越冬。由于该虫各世代总有极少部分个体进入滞育,少数进入越夏的个体1年只发生2代或3代。羽化时间多出现在上午7～10时,羽化后当日或次日下午交配,交配时间集中在下午3～6时,交配一般可持续12个h左右。成虫羽化后需取食花蜜做补充营养才能充分产卵。产配后次日即可产卵。第1代成虫常将卵数十粒聚产于幼嫩叶片的背面,以后各代主要聚产于花蕾上,平均每雌产卵量为43粒。幼虫为4龄。第1代主要取食叶芽、幼枝及嫩叶,以后各代主要取食花蕾。在自然条件下各虫态发育历期:卵为4～7d;幼虫为10～14d;非滞育的茧期(指幼虫结茧后的预蛹至成虫羽化的日期)为8～11d,越夏茧期为32～40d,越冬茧期为205～224d。成虫寿命为3～13d。     

Life history of the spider parasitoid Zatypota percontatoria (Hymenoptera: Ichneumonidae)

The life history of polysphinctine parasitoids is poorly understood. As a result, their effect on their host has not been evaluated. Here, we present the phenology of Zatypota percontatoria, an ectoparasitoid wasp of theridiid spiders, using rich field, semi‐field and laboratory investigations of selected life‐history parameters. The wasps overwintered as larva attached to the spider abdomen and the imagos of the first generation emerged at the beginning of May. The sex ratio (F/M) of overwintered wasp larvae was 1.4. The wasp spent an average of 6.4 days in the egg stage, 27.67 days in the larval stage and 9.6 days in the pupal stage. Adult longevity was on average 14.34 days. Oviposition occurred on average 8.44 days following maturity. The wasp laid on average 0.35 eggs/day. The total fecundity was on average 7.4 eggs per wasp and decreased with age (data from unmated females). The developmental rate increased with experimental temperature up to 28 °C. The lower developmental threshold for pupae was estimated at 6.6 °C. The sum of effective temperatures for pupae was estimated at 157.8 degree days. Using daily temperature records from the Czech Republic over the last 41 years, we estimated an average of 3.5 generations of Z. percontatoria per year. Mortality was 48% in semi‐field conditions and 23% in the laboratory. The incidence of mortality was highest during egg and larval stages caused by the detachment of eggs or larvae during spider molting, the mortality of the spider‐host and egg deposition on the spider prosoma.