橘小实蝇与番石榴实蝇卵及蛹的种间竞争

【背景】实蝇的竞争可能发生在生活史的各个阶段,但未见卵和蛹的种间竞争的相关报道。【方法】将橘小实蝇与番石榴实蝇的卵及蛹按照相应的比例或龄期分别进行混合培养,分析2种实蝇的卵或蛹混合后的发育历期和存活率是否受到彼此影响。【结果】橘小实蝇与番石榴实蝇的卵同龄等量混合,对彼此卵的历期和孵化率无影响。当橘小实蝇和番石榴实蝇的蛹为新鲜蛹时,分别与比它们蛹龄大1 d的对方蛹混合,蛹的羽化率分别为(87.67±3.61)%和(84.33±2.56)%,显著小于对照,说明在此混合蛹处理中,后化蛹者的发育可能受到先化蛹者的抑制。【结论与意义】总体上,在卵和蛹期,橘小实蝇与番石榴实蝇未产生竞争作用;但不排除蛹期竞争的可能性,这种竞争可能存在于特定的蛹期。     

Stages of diapause development in the pupa of Mamestra configurata based on the β-ecdysone sensitivity index

Four distinct stages of diapause development in pupae of Mamestra configurata held at 20°C can be recognized by means of the ‘β-ecdysone sensitivity index’. The latter refers to the ED50 of injected β-ecdysone required to break diapause in half of the treated pupae. Stage 1 begins with the newly-formed pupa, lasts about 3.5 days and is characterized by a rapidly falling ED50. Stage 2 lasts about four weeks during which the ED50 increases by almost 20-fold, from 0.27 μg/g at the beginning to 4.9 μg/g at the end. Stage 3 begins when the pupae are about 4 weeks old and lasts for about six weeks. Stage 3 is the stable diapausing state and is characterized by a virtually unchanging ED50. The onset of stage 4 occurs when the pupae are about 10 weeks old and is recognized by the beginning of a decline in the ED50. Stage 4 precedes the completion of diapause development and may signal the transition of the endocrine system to its active state.Pupal diapause deepens with time in M. configurata. The deepening process evidently occurs during stage 2 of diapause development. Pupae that were transferred to 5°C at the beginning of stage 2 failed to make the transition to stage 3 and were trapped in a very shallow diapause.     

Validation of reference genes for quantitative real‐time polymerase chain reaction in Drosophila melanogaster exposed to two chemicals

Drosophila melanogaster is attracted to chemicals produced by fermentation and it is abundantly found in rotten fruits. Considering its habitat, the fruit fly is reported to be tolerant to environmental chemicals. Quantitative real‐time polymerase chain reaction was employed to investigate the expression pattern and physiological function of genes putatively involved in chemical detoxification. In quantitative real‐time polymerase chain reaction assays, normalization of target gene expression with internal reference genes is required. These reference genes should be stably expressed during chemical exposure and in chemical‐free conditions. In this study, therefore, we used two programs (geNorm and BestKeeper) to evaluate the expression stability of five reference genes (nd, rpL18, ef1β, hsp22 and tbp) in female adult flies exposed to various concentrations of methanol and ethyl acetate. Four genes (nd, rpL18, ef1β and tbp) were found to be suitable for use as reference genes in methanol‐treated flies and three genes (ef1β, nd, tbp) were found to be suitable for use as reference genes in ethyl acetate‐treated flies. These results suggested that a combination of two genes among these stably expressed genes can be used for accurate normalization of target gene expression in quantitative real‐time polymerase chain reaction‐based determination of gene expression profiles in D. melanogaster treated with both chemicals.     

Degradation of endocrine disrupting chemicals by genetic transformants with two lignin degrading enzymes in <Emphasis Type="Italic">Phlebia tremellosa</Emphasis>

A white rot fungus Phlebia tremellosa produced lignin degrading enzymes, which showed degrading activity against various recalcitrant compounds. However, manganese peroxidase (MnP) activity, one of lignin degrading enzymes, was very low in this fungus under various culture conditions. An expression vector that carried both the laccase and MnP genes was constructed using laccase genomic DNA of P. tremellosa and MnP cDNA from Polyporus brumalis. P. tremellosa was genetically transformed using the expression vector to obtain fungal transformants showing increased laccase and MnP activity. Many transformants showed highly increased laccase and MnP activity at the same time in liquid medium, and three of them were used to degrade endocrine disrupting chemicals. The transformant not only degraded bisphenol A and nonylphenol more rapidly but also removed the estrogenic activities of the chemicals faster than the wild type strain.     

Interaction between a picornavirus and a wild population ofDrosophila melanogaster

Summary Drosophila C virus (DCV) has a considerable impact on ovarian morphogenesis inDrosophila melanogaster host populations. This virus also affects the developmental time and the fresh weight of infected females. In order to investigate the hypothesis that DCV may play a role in the dynamics ofDrosophila populations, the fertility and embryonic and larvo-pupal death rates of a host population and that of five DCV-free populations were determined. A comparison of two populations, one of them DCV-free, the other infected, suggested that the fertility of the DCV-infected flies was higher than that of uninfected flies, despite a greater larvo-pupal death rate. Fertility of the infected flies was greater among the infected population than for the DCV-free populations. The DCV-free populations originated from five different localities. The virus clearly does have an impact on the biotic potential of its host population. This paper reports for the first time a positive interaction between a viral population and a host population as it increases certain parameters of host population dynamics.     

Life history evolution and cellular mechanisms associated with increased size in high‐altitude Drosophila

Understanding the physiological and genetic basis of growth and body size variation has wide‐ranging implications, from cancer and metabolic disease to the genetics of complex traits. We examined the evolution of body and wing size in high‐altitude Drosophila melanogaster from Ethiopia, flies with larger size than any previously known population. Specifically, we sought to identify life history characteristics and cellular mechanisms that may have facilitated size evolution. We found that the large‐bodied Ethiopian flies laid significantly fewer but larger eggs relative to lowland, smaller‐bodied Zambian flies. The highland flies were found to achieve larger size in a similar developmental period, potentially aided by a reproductive strategy favoring greater provisioning of fewer offspring. At the cellular level, cell proliferation was a strong contributor to wing size evolution, but both thorax and wing size increases involved important changes in cell size. Nuclear size measurements were consistent with elevated somatic ploidy as an important mechanism of body size evolution. We discuss the significance of these results for the genetic basis of evolutionary changes in body and wing size in Ethiopian D. melanogaster.     

Gene expression and developmental rate

InD. melanogaster the genessc, D, L andvg were used to demonstrate the extragenic transmission of factors which change the expression of these genes.Many environmental conditions such as composition of the food influence the developmental rate which in turn can be shown to be primarily responsible for changing the expression of the genes.Genetic modifiers may act indirectly on the expression of these genes by changing the degree of fertility which, through relative crowding, may change the developmental rate.There is a parental effect which is presumably due to the size of the egg determining the developmental rate, environmental influences producing larger or smaller flies and thus determining the expression of the genes in the following generation.There is a grandparental effect which can be shown to be transmitted through the sperm and which usually determines the expression of the genes more strongly than the parental effect.The results can best be explained on the assumption that the various influences change the rate of reproduction of heterochromatic DNA in relation to euchromatic DNA and that, through extragenic transmission, these changes persist for at least two generations.This investigation was supported by N. S. F. Grant GB 1332.     

Ontogenetic thermal tolerance and performance of ectotherms at variable temperatures

Early experience and environmental conditions during ontogeny may affect organismal structure, physiology and fitness. Here, we assessed the effect of developmental acclimation to environmental thermal variability on walking speed in Drosophila melanogaster adults. Our results showed a shift in the performance curve to the right. Thus, upper and lower thermal limits exhibited developmental plasticity. Additionally, in constant and variable climatic scenarios, flies shifted to the right the optimum temperature but the maximum performance decreased only in flies reared on high temperatures and high thermal variability. Overall, we showed that environmental cues during ontogeny might help to construct phenotypic variation, which supports the hypothesis of ontogenetic dependence of thermal tolerances.     

Insecticidal and sublethal reproductive effects of Metarhizium anisopliae culture supernatant protein extract on the Mediterranean fruit fly

Because natural product‐based pesticides are thought to be more rapidly degradable than synthetic chemicals while having a lower ecotoxicological effect, the interest in these products for pest control has grown substantially. Recently, a new insecticide compound, which is the crude soluble protein extract (CSPE) from the fermentation product of the entomopathogenic fungus (EF) Metarhizium anisopliae (strain EAMa 01/58‐Su), has appeared in the literature as a promising insecticide for the control of the Mediterranean fruit fly, Ceratitis capitata. This CSPE has a moderate acute insecticide effect against adults of C. capitata when administered per os at 1 mg of protein/ml, as an exposure time of 8.3 h is necessary to get 50% of mortality. Even though the ingestion of this compound produces serious injuries in the midgut epithelium, it has a very low antifeedant effect on the flies. The effect of sublethal challenges on reproduction of adult flies was studied, and a reduction was found on the female fecundity levels during the first days after the treatment. On the other hand, the sublethal exposure to the CSPE affected neither the egg fertility nor the mortality of the larvae. However, the CSPE did affect the mortality of the pupae from the F1 generation, which suggests that there is a hormetic response from CSPE challenged females. The described sublethal reproductive effects are as important as direct lethal effects in contributing to the total value of the CSPE of the EF M. anisopliae 01/58‐Su strain.     

DISRUPTIVE SELECTION ON HABITAT PREFERENCE AND THE EVOLUTION OF REPRODUCTIVE ISOLATION: AN EXPLORATORY EXPERIMENT

A. pair of replicate experiments was carried out to examine the role of habitat specialization in the process of sympatric speciation. The rationale of the experimental design was that disruptive selection for habitat preference can facilitate the process of sympatric speciation by reducing an antagonistic interaction between the processes of recombination and selection. Replicate populations of Drosophila melanogaster were subjected to disruptive selection for habitat preference and simultaneous selection for positive assortative mating, for a period of 46 generations. The experimental protocol simulated the introduction of a frugivorous fly population into a new environment that contained a mosaic of eight equally abundant habitats. Only two habitats were suitable to the flies, and these required opposite patterns of geotaxis, phototaxis, chemotaxis, and developmental time to be successfully located. At the beginning of each generation, flies were placed as pupae into the middle of a maze containing eight discrete habitats. To produce disruptive selection on habitat preference, only those flies that chose one or the other of two selected habitats were permitted to contribute gametes to the next generation. Flies from each of the selected habitats were cultured separately to simulate independent carrying capacities within each habitat. Because flies rarely mated until they assorted themselves into the available habitats, genes affecting habitat preference pleiotropically produced assortative mating between flies with similar habitat preference. A genetic marker was used to continuously monitor the level of potential gene flow between the flies derived from the two selected habitats. During the course of the experiment, there was a gradual increase in the philopatry of the flies, indicating the development of habitat specialization. The evolution of habitat specialization resulted in substantial reproductive isolation between the subpopulations utilizing each habitat resource.     

Single and multigenerational responses of body mass to atmospheric oxygen concentrations in Drosophila melanogaster : evidence for roles of plasticity and evolution

Greater oxygen availability has been hypothesized to be important in allowing the evolution of larger invertebrates during the Earth’s history, and across aquatic environments. We tested for evolutionary and developmental responses of adult body size of Drosophila melanogaster to hypoxia and hyperoxia. Individually reared flies were smaller in hypoxia, but hyperoxia had no effect. In each of three oxygen treatments (hypoxia, normoxia or hyperoxia) we reared three replicate lines of flies for seven generations, followed by four generations in normoxia. In hypoxia, responses were due primarily to developmental plasticity, as average body size fell in one generation and returned to control values after one to two generations of normoxia. In hyperoxia, flies evolved larger body sizes. Maximal fly mass was reached during the first generation of return from hyperoxia to normoxia. Our results suggest that higher oxygen levels could cause invertebrate species to evolve larger average sizes, rather than simply permitting evolution of giant species.     

Preference and performance of peach fruit fly (Bactrocera Zonata) and Melon fruit fly (Bactrocera Cucurbitae) under laboratory conditions

In Pakistan and all over the world, the Peach Fruit Fly (PFF), Bactrocera zonata (Saunders.) and the Melon Fruit Fly (MFF), Bactrocera cucurbitae (Coquillett.) are considered severe and polyphagous insect pests for various fruits and vegetables. The current study was conducted to check the Laboratory preference and performance of B. cucurbitae and B. zonata on selected Fruits Citrus (Citrus sinensis), Apple (Malus domestica), Banana (Musa acuminate), and vegetable, Sponge gourd (luffa aegyptiaca), Bitter gourd (Momordica charantia) Pumpkin (Cucurbita moschata) under laboratory conditions. The study showed that Sponge Gourd was the preferable host with the mean pupae resurgence of (242.33), followed by Bitter Gourd (78.333) among selected vegetables. At the same time, among fruits, a banana was the preferable host with mean pupae resurgence (204.33), followed by orange (158.33). The pumpkin and apple was the least preferable host for both B. cucurbitae and B. zonata, with mean pupae resurgence (35.667) and (79.000), respectively. Furthermore, the study showed that Banana was the preferable host for B. Zonata among intact and infested fruits, whereas B. cucurbitaee showed the most preference to Bitter gourd among intact and infested vegetables showing significantly different results among intact and infested fruits and vegetables. Maximum number of eggs, pupa, female flies, male flies, adult emergence from pupa (flies) and period of pupa of B. zonata and B. cucurbitae on banana and bitter gourd. While, other fruits and vegetables showed the minimum number of eggs, pupa, female flies, male flies, adult emergence from pupa (flies) and period of the pupa. The current study concluded there is a need to evaluate other host plants against these fruit fly species for effective control.     

Intra-puparial development in the hoverflies Eristalinus aeneus and Eristalis tenax (Diptera: Syrphidae)

The intra-puparial development of 150 pupae of Eristalinus aeneus (Scopoli, 1763) and Eristalis tenax (Linnaeus, 1758) was analyzed. Individuals were obtained from the sixth laboratory generation kept under artificial rearing conditions at the facilities of the University of Alicante (Spain). The experiment was conducted at 25 ± 1°C temperature, 50 ± 5% relative humidity, and 12:12 hr (L:D) of photoperiod. Groups of 10 pupae were collected every 6 hr over 48 hr, after that period, pupae were collected daily until the adult emergence. They were fixed in 5% formic acid and preserved in 70% ethanol. Fixed pupae were dissected and photographed. The chronology and morphological changes that take place during the intra-puparial development in both species were analyzed and compared. Five phases were observed: prepupa, before 6 hr; cryptocephalic pupa, between 6 and 24 hr; phanerocephalic pupa, between 24 and 30 hr; pharate adult, after 30 hr; and the adult imago, restricted to the very end of the development process just before adult emergence. In total, the intra-puparial development lasted 189 ± 4 hr in E. aeneus and 192 ± 3 hr in E. tenax, with the pharate adult the longest phase (some 81% of the total developmental time). These data can be used to develop accurate cold storage protocols during artificial rearing of both pollinator species, avoiding critical events during the development and increasing survival.     

Rapid within‐ and transgenerational changes in thermal tolerance and fitness in variable thermal landscapes

Phenotypic plasticity may increase the performance and fitness and allow organisms to cope with variable environmental conditions. We studied within‐generation plasticity and transgenerational effects of thermal conditions on temperature tolerance and demographic parameters in Drosophila melanogaster. We employed a fully factorial design, in which both parental (P) and offspring generations (F1) were reared in a constant or a variable thermal environment. Thermal variability during ontogeny increased heat tolerance in P, but with demographic cost as this treatment resulted in substantially lower survival, fecundity, and net reproductive rate. The adverse effects of thermal variability (V) on demographic parameters were less drastic in flies from the F1, which exhibited higher net reproductive rates than their parents. These compensatory responses could not totally overcome the challenges of the thermally variable regime, contrasting with the offspring of flies raised in a constant temperature (C) that showed no reduction in fitness with thermal variation. Thus, the parental thermal environment had effects on thermal tolerance and demographic parameters in fruit fly. These results demonstrate how transgenerational effects of environmental conditions on heat tolerance, as well as their potential costs on other fitness components, can have a major impact on populations’ resilience to warming temperatures and more frequent thermal extremes.     

Effect of semolina-jaggery diet on survival and development of Drosophila melanogaster

Drosophila melanogaster is an ideal model organism for developmental studies. This study tests the potential of semolina-jaggery (SJ) diet as a new formulation for bulk rearing of flies. Semolina and jaggery are organic products obtained from wheat endosperm and cane sugar, respectively. Semolina is a rich source of carbohydrates and protein. Jaggery has a high content of dietary sugars. Moreover, preparation of semolina jaggery diet is cost-effective and easy. Thus, the current study aimed to compare survival and developmental parameters of flies fed the SJ diet to flies fed the standard cornmeal-sugar-yeast (CSY) diet. SJ diet enhanced survival of flies without affecting fecundity; male flies showed increased resistance to starvation. A higher number of flies emerged at F₂ and F₃ generation when fed the SJ diet than when fed the control CSY diet. SJ diet did not increase fly body weight and lipid percentage. Therefore, SJ diet can be used for bulk rearing of healthy flies at par with the standard cornmeal-sugar-yeast diet.     

Enhanced expression of laccase during the degradation of endocrine disrupting chemicals in Trametes versicolor

A putative laccase cDNA from a white-rot basidiomycete, Trametes versicolor, that consisted of 1,769 nucleotides was cloned using the rapid amplification of cDNA ends (RACE)-PCR method. The deduced amino acid sequence had 4 putative copper binding regions, which are common to fungal laccases. In addition, the sequence was 57 approximately 97 % homologous to sequences of other T. versicolor laccases. Additionally, the expression of laccase and manganese peroxidase in this fungus were both greatly increased under degrading conditions for bisphenol A, nonylphenol and two phthalic esters (benzylbutylphthalate and diethylphthalate), all of which are reportedly endocrine disrupting chemicals (EDCs). Furthermore, the estrogenic activities of the EDCs also decreased rapidly during incubation when examined in a two-hybrid yeast system. Finally, kojic acid inhibited the removal of estrogenic activities generated by bisphenol A and nonylphenol, which confirmed that laccase was involved in the degradation of EDCs in T. versicolor.     

The avoidance of superparasitism in four species of parasitic wasp—Mathematical models and experimental results

Experimental results, and interpretation, are presented which relate to oviposition behaviour in four species of parasitic wasp (Hymenoptera: Chalcidoidea). All lay their eggs in pupae of the common house fly (Musca domestica) and of other flies associated with man. Probability models suggested byD. J. Daley for describing the avoidance of superparasitism are used to analyse the data. Certain of the models considered by previous authors appear as specieal cases. A satisfactory fit was obtained either by assuming a fixed probability of oviposition in an already parasitised pupa, or by using a model motivated by supposing that a female will tolerate without oviposition some fixed number of visits to already parasitised pupae. A third model was considered which makes the probability depend on the number of previous ovipositions in the pupae now visited. In all four species the presence of other females (with parasite: host ratio unchanged) increased the probability of oviposition upon encountering an already parasitised pupa. In the presence of other females Spalangia endius laid an increased number of eggs, whereas the other three species laid fewer eggs.     

Radiation biology and inherited sterility of light brown apple moth (Lepidoptera: Tortricidae): developing a sterile insect release program

The radiation biology of two geographically isolated populations of the light brown apple moth [Epiphyas postvittana (Walker)] was studied in Australia and New Zealand as an initiation of a SIT/F1 sterility program. Pharate and < or = 2 d pre-emergence pupae were exposed to increasing radiation doses up to a maximum dose of 300 Gy. Fertility and other life history parameters were measured in emerging adults (parental) and their progeny (F1-F3 adults). Parental fecundity was significantly affected by increasing irradiation dose in pharate pupae only. For both populations, parental egg fertility declined with increasing radiation. This was most pronounced for the irradiated parental females whose fertility declined at a higher rate than of irradiated males. At 250 Gy, females < or = 2 d preemergence pupae produced few larvae and no adults at F1. No larvae hatched from 250 Gy-irradiated female pharate pupae. At 300 Gy, males still had residual fertility of 2-5.5%, with pharate pupae being the more radio-sensitive. Radiation-induced deleterious inherited effects in offspring from irradiated males were expressed as increased developmental time in F1 larvae, a reduction in percent F1 female survival, decreased adult emergence and increased cumulative mortality over subsequent generations. Males irradiated at > or = 150 Gy produced few but highly sterile offspring at F1 and mortality was > 99% by F2 egg.     

Effect of temperature on pupa development and sexual maturity of laboratory Anastrepha obliqua adults

The effect of four temperatures (18, 20, 25 and 30°C) on pupa development and sexual maturity of Anastrepha obliqua adults was investigated under laboratory conditions. The results showed that the duration of the pupal stage decreased with an increase in temperature (29, 25, 13 and 12 days, respectively), and maintaining the pupae at 18°C and 20°C results in a low percentage of pupation, pupa weight loss and lesser flying ability. However, it significantly favored sexual behavior, a higher proportion of sexual calls and matings. While enhanced pupa development was observed at a temperature of 30°C, adults had low sexual efficiency, as well as a lower proportion of calls and matings. Gas chromatography-mass spectrometry (GC-MS) analysis of male volatiles showed that the amount of (Z,E)-α-farnesene did not vary among males from pupae reared at different temperatures; however, less (E,E)-α-farnesene was emitted by males obtain from pupa reared at 30°C. Male flies kept at 30°C during their larval stage had more (Z)-3-nonenol and, also, an unknown compound was detected. The fecundity of the females was higher at low temperatures. Regarding fertility, no significant differences were found between temperatures. The optimal temperature on pupa development was 25°C when males displayed ideal attributes for rearing purposes.     

Radiation biology and inherited sterility in false codling moth (Lepidoptera: Tortricidae)

False codling moth, Cryptophlebia leucotreta (Meyrick), male and female mature pupae and newly emerged adults were treated with increasing doses of gamma radiation and either inbred or out-crossed with fertile counterparts. For newly emerged adults, there was no significant relationship between dose of radiation and insect fecundity when untreated females were mated to treated males (N female by T male). However, fecundity of treated females mated to either untreated (T female by N male) or treated males (T female by T male) declined as the dose of radiation increased. A similar trend was observed when mature pupae were treated. The dose at which 100% sterility was achieved in treated females mated to untreated males (T female by N male) for both adults and pupae was 200 Gy. In contrast, newly emerged adult males treated with 350 Gy still had a residual fertility of 5.2% when mated to untreated females, and newly emerged adult males that were treated as pupae had a residual fertility of 3.3%. Inherited effects resulting from irradiation of parental (P1) males with selected doses of radiation were recorded for the F1 generation. Decreased F1 fecundity and fertility, increased F1 mortality during development, and a significant shift in the F1 sex ratio in favor of males was observed when increasing doses of radiation were applied to the P1 males.