Life table and biological studies of Harmonia axyridis Pallas (Col., Coccinellidae) reared on the grain moth eggs of Sitotroga cerealella Olivier (Lep., Gelechiidae)

The developmental period of immature stages, survival per cent, longevity, fecundity and life table parameters of Harmonia axyridis by feeding on fresh and frozen grain moth eggs (GME) of Sitotroga cerealella were studied under laboratory conditions. The effect of crowding adults on fecundity of females was also determined. The total developmental time from egg hatching to adult eclosion ranged from 18.89 ± 0.32 to 22.5 ± 0.21 days on fresh and frozen GME, respectively. Survival per cent from egg hatching to adult emergence differed significantly when the predator fed on the two diets of GME. Also, pupal and adult weights were affected by feeding on fresh and frozen GME. There were no significant differences in longevity of females, while there were significant variations in fecundity of females and longevity of males. The calculated values of T , DT , R_o , r_m , and e^rm were high by feeding on fresh GME. Morever, rates of survivorship ( Lx ), and maximum oviposition per female per day ( Mx ) were higher when the predator was reared on fresh than on frozen GME. Crowding conditions of predator adults affected the fecundity of females due to egg cannibalism by both males and females of the predator.     

橘小实蝇遗传性别品系的建立及雄性不育技术

为了更好地应用昆虫不育技术防治橘小实蝇,建立了以蛹色区分雌雄性别的橘小实蝇遗传性别品系。经过连续测交表明遗传品系能稳定遗传。质量监测表明遗传性别品系平均孵化率、蛹重、羽化率、飞出率、存活率等指标与普通种无显著差异。取遗传性别品系羽化前1、2、3天（分别用-1 d、-2 d、-3 d表示）的雄蛹,经过100 Gy的⁶⁰Co辐射后,分别与野生雌虫杂交,F1代卵的孵化率均大大低于对照组。对经过辐射处理-1 d、-2 d、-3 d的雄蛹分别进行质量检测,飞出率、存活率与对照组均无显著差异;-1 d、-2 d的羽化率之间及与对照组之间无显著差异,-3 d的羽化率与-1 d、-2 d及对照组差异均显著。取遗传性别品系的-2d的雄蛹辐射100 Gy的⁶⁰Co,获得不育雄虫,和野生雄虫一起竞争与野生雌虫交配的机会,相对不育系数为0.4923,表明不育雄虫与野生雄虫交配能力相当。田间扩散能力研究表明,不育雄虫在田间存在丰富的寄主植物的情况下不会大量扩散很远的距离。     

Enhanced longevity in tau mutant Syrian hamsters,Mesocricetus auratus

The single-gene mutation tau in the Syrian hamster shortens the circadian period by about 20% in the homozygous mutant and simultaneously increases the mass-specific metabolic rate by about 20%. Both effects might be expected to lead to a change in longevity. To test such expectations, the life span of male and female hamsters from three genotypes (wild-type, heterozygous, and homozygous tau mutants, all derived from heterozygote crosses to randomize the genetic background) was recorded in constant darkness. Male hamsters lived significantly longer than females: the overall average life span was 96.9 weeks (SE = 2.5, n = 118) for males and 82.0 weeks (SE = 2.1, n = 99) for females. To our surprise, male and female homozygous mutant hamsters lived significantly longer rather than shorter compared to wild-types. For males, the difference between the two genotypes was on average 14%; for females, the difference was 16%. The mortality rate of wild-type males was significantly different from that of homozygous tau males but not different from that of heterozygotes. Overall, survival of wild-type females was statistically distinguishable from both heterozygous and homozygous mutant females. Male and female wild-type hamsters were heavier than homozygote mutants throughout the entire life span, and heterozygous mutants had intermediate weights. There was no correlation between body mass and life span, and the causes of the extended life span in tau mutant hamsters remain unresolved.     

梨小食心虫蛹重对成虫繁殖力和寿命及下一代幼虫发育的影响

【目的】本文旨在明确营养状况不同造成的梨小食心虫Grapholitha molesta(Busck)雌、雄蛹重量差异对其羽化的成虫产卵量、产卵期、寿命及下一代(F1)幼虫发育的影响。【方法】室内条件下,通过不同的饲养方法,获得个体重量不同的梨小食心虫雌、雄蛹,待其羽化交配后,记录其产卵量、产卵时间和成虫寿命;卵孵化前后,分别测量卵和初孵幼虫大小,计算卵孵化率,统计幼虫发育历期。【结果】雌蛹重量对梨小食心虫的成虫产卵量影响显著,其重量与产卵量呈正相关(y=15.505x-59.292);同一条件下,雌蛹与雄蛹重量也呈正相关(y=0.823x-0.538)。同时,雌蛹重量对成虫产卵期影响也较大,蛹重大的个体羽化的雌虫比蛹重小的个体羽化的雌虫产卵高峰期提前1 d;较重、中等和较轻蛹羽化出的雌虫个体每天产卵量高于10粒/雌的时间分别为9~10,7和5~6 d;产卵量高于5粒/雌的时间分别为12~13,9和6~7 d。而雄蛹重量对产卵量、雄成虫寿命影响没有明显影响。较轻的蛹羽化的雌成虫寿命比较重蛹羽化的雌成虫短2~3 d;而雄蛹重量对其羽化的雄成虫寿命影响没有明显规律。雌、雄蛹重量对其羽化成虫的卵孵化率、卵和初孵幼虫的大小影响均不显著,对F_1幼虫发育历期影响也不显著。【结论】梨小食心虫雌蛹重对羽化成虫的产卵量和产卵期等影响显著,田间防治时应注意在不同条件下完成发育的个体,尤其是雌虫,由于营养差异引起的个体大小对随后种群增长的影响。     

The relationship between size and reproductive potential in male and female Epirrita autumnata (Lep., Geometridae)

Abstract. 1. We studied the fecundity of Epirrita autumnata Bkh. (Lepidoptera) in relation to pupal weight of females and males.
2. There was no clear correlation between male size and the success in fertilization over a considerable range of weights (from 50 mg to over 100 mg) although in one experiment only large males were successful in multiple fertilizations.
3. In the three experiments where small males (<50 mg) were used they showed reduced performance, and a large proportion of them was sterile.
4. Unlike in males, the number of eggs laid by females correlated linearly with pupal weight over the whole range of female weights.     

Inheritance of weight in Rhipicephalus appendiculatus ticks (Acari: Ixodidae) in the laboratory

A selection of the 10% lightest and 10% heaviest males and females of a population of individually weighed Rhipicephalus appendiculatus Neumann adults was made in two experiments. The offspring of homologous pairs were followed until the next adult stage (light x light, control x control and heavy x heavy). The engorged nymphal weights, unfed adult weights, engorged female weights of the parents, egg mass weights, egg weights, larval scutal lengths, engorged larval weights, unfed nymphal weights, engorged nymphal weights and adult weights of the progeny were determined. No significant differences could be demonstrated between the two lines for egg weight, larval scutal length, engorged larval weight and unfed nymphal weight. Significant differences were found between the egg masses, engorged nymphal weights and adult weights of the two lines. The heritability coefficients of body weight determined from adult to adult were 0.14 and 0.10, respectively, during the first and second experiments. Considering females and males separately, the coefficients were 0.10 and 0.18 during the frist experiment and 0.12 and 0.09 during the repeat experiment respectively.     

Injection of diethylstilbestrol on the first day of incubation affects morphology of sex glands and reproductive behavior of Japanese quail

Japanese quail eggs were injected with DES (0.9-1,000 micrograms) dissolved in 50-microliter of corn oil on day 1 of incubation. Higher doses of DES (250-1,000 micrograms) reduced hatchability to 37-33% compared to 61% for corn oil-injected controls. Lower doses of DES (0.9-125 micrograms) had no effects on hatchability. In a second study, eggs were injected with 0.9 or 1.9 micrograms of DES and the survivors were assessed up to 12 weeks posthatch. DES did not affect hatchability, but did increase mortality during the first 4 weeks posthatch. Females were affected more than males. At 10 days of age, open-field activity of some birds was examined. The acquisition and reversal of a visual discrimination task was studied at 6 weeks of age. DES had no effect on these measurements. Ten females from each group were chosen randomly to determine egg production over a single 28-day period beginning at 6 weeks of age. Exposure to DES blocked egg production in these birds. The oviduct weights of 12-week-old females were decreased by 50%, but ovarian weights were not affected. Testicular weights were not affected. In a third study reproductive behaviors and social-dominance behaviors of males were markedly attenuated in birds exposed to 0.48 or 1.9 micrograms DES in ovo.     

Comparative rearing parameters for bisexual and genetic sexing strains of Zeugodacus cucurbitae and Bactrocera dorsalis (Diptera: Tephritidae) on an artificial diet

The Sterile Insect Technique (SIT) is an important component of area wide programs to control invading or established populations of pestiferous tephritids. The SIT involves the production, sterilization, and release of large numbers of the target species, with the goal of obtaining sterile male x wild female matings, which yield infertile eggs. A major advance in SIT involved sex-linked, genetic manipulations that allowed the production and release of male-only strains (also termed genetic sexing strains, GSS). The use of GSS avoids matings between sterile males and females, which may divert males from seeking and mating with wild females, and studies show that male-only releases result in greater suppression of wild populations than standard bisexual releases (i.e., those including both males and females). GSS based on sex-linked pupal color exist for Zeugodacus cucurbitae (Coquillett) and Bactrocera dorsalis (Hendel), two important agricultural pest species, but their rearing characteristics have not been documented in detail. The goal of the present study was to compare the pupal color sexing and bisexual strains for each of these species with respect to important rearing parameters, including egg production and eclosion of larvae from eggs (egg hatch), pupal recovery, and weight, emergence rate, and flight ability. In both species, most of these parameters were significantly greater for the bisexual strain than the GSS, and, for a given number of eggs, the production of flight-capable adults was approximately 2 times greater in the bisexual strains of both species. The potential usefulness of GSS in SIT against Z. cucurbitae and B. dorsalis is assessed based on these findings.     

Quantitative Genetics of Transgenic Mice: Components of Phenotypic Variation in Body Weights and Weight Gains

Transgenic mice possessing an ovine growth hormone gene were used to study the effects of elevated growth hormone on quantitative genetic variation. Males hemizygous for the transgene were mated to wild-type females to produce half- and full-sib families in which approximately half the progeny were transgenic and half were wild type. Analyses of body weights at 3-10 weeks, and weight gains from 3 to 6, and 6 to 10 weeks produced estimates of the proportion of total variance due to additive genetic effects (h(2)) and common litter effects (c(2)), and the genetic correlation between transgenic and wild-type expression of each trait. At 10 weeks, body weight of transgenics exceeded that of wild types by 26 and 49% in males and females, respectively. Estimated genetic variances in the transgenic group were significantly greater than zero for body weights at most ages and for both measurements of gain. Common litter effects accounted for a similar proportion of variation in the wild-type and transgenic groups. Additive genetic correlations between wild-type and transgenic expression of body weights tended to decline with age, indicating that a partially different array of genes may have begun to affect body weight in the transgenic group.     

Sublethal effects of chronic exposure to tebufenozide on the development, survival, and reproduction of the tufted apple bud moth (Lepidoptera: Tortricidae)

The lethal and sublethal effects of tebufenozide on the survival, development, and reproduction of a field strain of tufted apple bud moth, Platynota idaeusalis (Walker) (Lepidoptera: Tortricidae), were assessed by feeding first and third instars tebufenozide-treated diet until pupation. Larval mortality was 27.4 and 44.7% at 0.1 and 0.2 ppm for first instars and 21.9 and 57.8% at 0.2 and 0.4 ppm for third instars, respectively. Treated larvae exhibited higher pupal mortalities, lower pupal weights, and generally more deformed adults than untreated larvae. Larval development was not affected by tebufenozide when neonates were exposed, but development was accelerated slightly at 0.4 ppm for both males and females when third instars were exposed. All treatments produced sex ratios biased toward males. When paired with either treated or untreated males, females resulting from neonates treated at 0.2 ppm and from third instars treated at both 0.2 and 0.4 ppm laid from 37 to 65% fewer eggs. A reduction in fertility was only found when third instars were treated at the higher 0.4 ppm rate. These results suggest that tebufenozide can exhibit a significant effect on the population dynamics of the tufted apple bud moth.     

Inheritance of a temperature-modified phenotype of the short antennae (sa) mutation in a moth, Ephestia kuehniella (Lepidoptera: Pyralidae).

The autosomal recessive mutation short antennae (sa) causes considerable shortening of antennae in male and female Mediterranean flour moths (Ephestia kuehniella Zeller). However, the sa phenotype can be suppressed by several physical factors, making sa moths indistinguishable from wild-type moths (sa(WT)). This can be done by subjecting larva and pupa to a higher temperature (25 degrees C), to lithium ions, or to an alternate electric field. The first half of pupal development was found to be the sensitive period for the sa(WT) phenotype. The sa(WT) phenotype is stable and cannot be reverted to the original sa type by physical or chemical factors. The sa(WT) phenotype is transmitted to future generations. When crossed with typical sa moths, the sa(WT) phenotype is inherited either as a dominant character if carried by males or a semidominant character if carried by females. We compared proteins of the ejaculate, accessory gland secretions, and spermatophore in sa, sa(WT), and wild-type males and found considerable differences between sperm proteins of sa(WT), sa, and wild-type males. The sa(WT) phenotype influences the mating success of males: sa(WT) males mated successfully with any females, whereas typical sa males were less successful in mating and then mainly with females of the same phenotype.     

Pre-release analysis of the overwintering capacity of a classical biological control agent supporting prediction of establishment

This study investigated the effect of temperature on the development and overwintering capacity of the pupal parasitoid, Diadromus pulchellus Wesmael (Hymenoptera: Ichneumonidae), a candidate classical biological control agent against leek moth, Acrolepiopsis assectella (Zeller) (Lepidoptera: Acrolepiidae) in Canada. It was estimated that 256.4 day-degrees, above a lower threshold temperature of 7.3°C, were required for D. pulchellus to complete development, from egg to adult eclosion. Laboratory and field experiments on the immature and mature parasitoids indicated that D. pulchellus overwinters primarily, if not exclusively, in the adult stage. Only adults were able to survive an entire winter under natural outdoor conditions in central Europe. Immature parasitoids developing inside their pupal hosts were capable of withstanding short periods of temperatures as low as −5°C or −10°C, but even much higher temperatures were lethal if sustained for several weeks. Among adults, females demonstrated greater cold hardiness than males. The LTime₅₀ at −12°C, simulating winter temperatures without snow cover, was 4–5 and 6–7 days for males and females, respectively. The LTime₅₀ at −4°C, simulating winter temperatures beneath an insulating snow layer, was 1–2 and 2–3 weeks for males and females, respectively, with maximum survival of eight weeks. It is likely that survival would be even greater in a natural environment where the parasitoids could select optimal overwintering sites and have the option to feed when temperatures rise enough to permit activity. Based on these results, D. pulchellus is expected to survive winters in the targeted release areas of Ontario and Quebec.     

Evolutionary genetics of Drosophila ananassae: evidence for trade-offs among several fitness traits

Correlated responses to bi‐directional selection on thorax length, examined on several life‐history traits and chromosome inversion polymorphisms, have revealed apparent novel trade‐offs in Drosophila ananassae. We provide evidence of trade‐offs between hatching time and pupal period, pupal period and egg‐pupa development time, and pupal period and larval development time (LDT). Body size shows positive correlations with ovariole number, LDT and DT (egg–fly). We provide evidence of sexual dimorphism for trade‐offs between longevity and body size and starvation and longevity in females only. Trade‐offs between wing/thorax (W/T) ratio and longevity, W/T ratio and starvation, and DT (egg‐ fly) and longevity are evident in males only. Sexual dimorphism is also evident for inversion polymorphism with body size and longevity. A longevity assay suggests that low line females outlived high line females whereas high line males outlived low line males. The mean longevity in males is negatively correlated with the 2L‐ST and 3R‐ST arrangement frequencies whereas the 3L‐ST arrangement frequency is positively correlated with the mean longevity in males but opposite arrangements are found in females. Absolute starvation resistance is negatively correlated with 2L‐ST and 3R‐ST chromosome arrangements and results in a trade‐off between longevity and absolute starvation resistance in females. Analyses of fecundity, hatchability, and viabilities based on age intervals in both G₁₀ and G₁₃ suggest that the early reproduction is favoured in D. ananassae. The productivity percentage is highest in the high line and there is no effect of late reproduction on it. Overall, we provide some unravelled trade‐offs and striking sex differences, which may help in understanding the life‐history evolution of the species. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 90 , 669–685.     

Polyphagy,flightlessness, and reproductive output of females: a case study with bagworms (Lepidoptera: Psychidae)

Abstract 1. We evaluated the relation between plant‐mediated larval traits and the fitness of female bagworms, Thyridopteryx ephemeraeformis Haworth (Lepidoptera: Psychidae) by sampling 29 populations of bagworms on five plant genera (Thuja, Pinus, Picea, Juniperus, and Gleditsia). 2. Compared with those on other genera of plants, female larvae on Thuja attained a larger size at pupation and developed faster. The superior quality of Thuja as a larval food plant resulted in a higher potential fitness of females, as indicated by a low level of pupal mortality and high fecundity. 3. The fecundity of females increased with pupal size on different plant genera, and the effect of host plant genus was negligible compared with pupal size. 4. The mating success of females varied among different populations (0–37% unmated females), but neither host plant, emergence time, nor the size of females had a significant influence on the proportion of mated females. 5. The conversion of adult biomass into reproductive tissue, measured as the ratio between the biomass of eggs divided by the biomass of calling females, increased with the pupal size of females and approached 90% for large females. The high rate of egg conversion in bagworms may be related to the neoteny of short‐lived females that invest little in somatic tissue.     

Lethal and sublethal effects of methoxyfenozide on the development, survival and reproduction of the fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae)

The lethal and sublethal effects of the ecdysone agonist methoxyfenozide on the fall armyworm, Spodoptera frugiperda (J. E. Smith), were investigated by feeding a methoxyfenozide-treated diet to fifth instars until pupation in doses corresponding to the LC10 and LC25 for the compound. Larval mortality reached 8% and 26% in the low and high concentration groups, respectively, on the seventh day of the experiment. A progressive larval mortality of 12% for the LC10 and 60% for the LC25 was observed before pupation. Treated larvae exhibited lower pupal weights, higher pupal mortality, presence of deformed pupae, and more deformed adults than untreated larvae. The incorporation of methoxyfenozide into the diet had a significant effect on the timing of larval development. The development period for males and females was about seven days longer than the controls for both concentrations tested. In contrast, the compound affected neither pupae nor adult longevity. Finally, S. frugiperda adults that resulted from fifth instars treated with methoxyfenozide were not affected in their mean cumulative number of eggs laid per female (fecundity), nor percentages of eggs hatched (fertility), or the sex ratio. Our results suggest that the combination of lethal and sublethal effects of methoxyfenozide may have important implications for the population dynamics of the fall armyworm.     

The Genetics of Melanism in MALACOSOMA DISSTRIA HUbner (Lepidoptera: Lasiocampidae)

The forest tent caterpillar is polymorphic for two melanic genes affecting wing color of moths. These are the first genetically determined morphological traits reported for the genus. Dark (D) is a sex-limited, autosomal dominant with a phenotype of dark brown males. Frequencies in population samples varied from 8 to 44%. Characteristics of Dark and nonmelanic males were compared. Larval development times, larval survival and pupal weights were not significantly different, but mean fecundity was higher for females with Dark progeny. Band (b), a darkened area across the forewings, occurred in low frequency in both sexes.     

Life-history responses of the rice stem borer Chilo suppressalis to temperature change: Breaking the temperature–size rule

Temperature is a key environmental factor for ectotherms and affects a large number of life history traits. In the present study, development time from hatching to pupation and adult eclosion, pupal and adult weights of the rice stem borer, Chilo suppressalis were examined at 22, 25, 28 and 31 °C under L18:D 6. Larval and pupal times were significantly decreased with increasing rearing temperature and growth rate was positively correlated with temperature. Larval and pupal developmental times were not significantly different between females and males. The relationship between body weight and rearing temperature in C. suppressalis did not follow the temperature–size rule (TSR), both males and females gained the highest body weight at 31 °C. Females were significantly larger than males at all temperatures, showing a female biased sex size dimorphism (SSD). Contrary to Rensch's rule, SSD and body weight in C. suppressalis tended to increase with rising temperature. Male pupae lost significantly more weight at metamorphosis compared to females. We discuss the adaptive significance of the reverse-TSR in the moth's life history.     

Isolation and Characterization of Sex-Linked Female-Sterile Mutants in DROSOPHILA MELANOGASTER

The purpose of the experiments described was to identify X chromosome genes functioning mainly or exclusively during oogenesis. Two mutagenesis experiments were carried out with ethyl methane sulfonate. Following treatment inducing 60% lethals, 9% of the treated X chromosomes carried a female sterility mutation which did not otherwise seriously affect viability. Among —95 isolated mutants, 19 were heat-sensitive and 5 cold-sensitive. The mutants have been classified as follows: I (16 mutants; 12 complementation groups): the females laid few or no eggs; the defect concerned either ovulation or oogenesis. II (37 mutants; 18 complementation groups): the female laid morphologically abnormal eggs, often with increased membrane permeability. III A (13 mutants; at least 8 complementation groups): the homozygous females were sterile if mated to mutant males; their progeny (homo- and hemizygous) died at a late embryonic stage (11 mutants), at the larval stage (1 mutant) or at the pupal stage (1 mutant). However fertility was partly restored by breeding to wild-type males as shown by survival of some heterozygous descendants. III B (29 mutants; 22 complementation groups): the fertility of the females was not restored by breeding to a wild-type male. Most of the eggs of 13 of the mutants died at a late stage of embryogenesis. The eggs of the others ceased development earlier or, perhaps, remained unfertilized. The distribution of the number of mutants per complementation group led to an estimation of a total of about 150 X-linked genes involved in female fertility. The females of three mutants, heat-sensitive and totally sterile at 29°, produced at a lower temperature descendants morphologically abnormal or deprived of germ cells. Three other mutants not described in detail showed a reduction in female fertility with many descendants lacking germ cells. A desirable mutant which was not recovered was one with normal fertile females producing descendants which, regardless of their genotype, bore specific morphological abnormalities. The value of the mutants isolated for analysis of the complex processes leading to egg formation and initiation of development is discussed.     

A synopsis of the obligate and facultative insect parasitic nematodes

A study of the pathogenicity of a cytoplasmic polyhedrosis virus of the gypsy moth, Porthetria dispar, was conducted. Third- and fourth-instar larvae were highly susceptible to the pathogen even when fed low dosages of polyhedra. Only 30–50% of the treated insects died of polyhedrosis, but the debilitating effects of the virus on larval and postlarval stages were remarkable. Pupal weights were consistently reduced. An inverse and, respectively, a direct, relationship was found between the size of diseased specimens and the developmental periods of larvae and pupae surviving to lethal infection. The highest infected male adults showed a lighter wing coloration. Structural abnormalities and melanotic abdominal inclusions, recorded in diseased adults, were more frequent in females than in males. The presence of melanotic inclusions in diseased females obtained from early larval infection experiments was associated with a greater pupal weight. Lower dosages were the most effective in producing larval mortality and reducing pupal weights and adult emergence. An interference phenomenon due to a mixed virus infection is suspected.     

Genetic and environmental sources of egg size variation in the butterfly Bicyclus anynana

By dividing families of the tropical butterfly, Bicyclus anynana, among different larval (including early pupal) and adult (including late pupal) temperatures, we investigate the genetic and environmental effects on egg size. Both sources of variation affected egg size to similar extents. As previously found in other arthropods, egg size tended to increase at lower temperatures. Our data suggest that the plastic response in egg size can be induced during the pupal stage. Females reared as larvae at the same high temperature tended to lay larger eggs when transferred to a lower temperature, either as prepupae or pupae, compared to those remaining at the high temperature. Additionally, females reared as larvae at different temperatures, but maintained at the same temperature from the early pupal stage onwards, laid larger eggs after larval growth at a low temperature. Heritability estimates for egg size were about 0.4 (parent-offspring regression) and 0.2 (variance component estimates using the full-sib families). Although there seemed to be some variation in the plastic response to temperature among families, genotype-environment interactions were nonsignificant.