Effects of parental radiation exposure on developmental instability in grasshoppers

Assessment of combining biosynthesized silver nanoparticles using Bacillus thuringiensis and gamma irradiation for controlling Pectinophora gossypiella (saunders) (lepidoptera: Gelechiidae)

PURPOSE

Combining gamma irradiation and nanotechnology has become one of the most promising new approaches for area-wide (AW) pest management in recent years. The laboratory trials were conducted to determine the combining effects of BT-AgNPs and gamma irradiation for controlling P. gossypiella. Radio-sensitivity of male pupae at different doses of gamma radiation and the effectiveness of biosynthesized silver nanoparticles using Bacillus thuringiensis on larval instar were assayed. Additionally, the ultrastructure changes on the alimentary canal of 4th instar larvae were studied to evaluate the impact of the combined approach at a cellular level.

MATERIALS AND METHODS

Laboratory- rearing technique was used for rearing Pectinophora gossypiella. The irradiation process was achieved at Co60 - Gamma Chamber (4000 A). Alanine dosimeters were used for measuring the average absorbed dose and dose mapping. Preparation of Silver nanoparticles (AgNPs) using Bacillus thuringiensis (Bt) and their characterization has been investigated. The treated 4th instar larvae by gamma irradiation or ∕and BT-AgNPs were dissected under the stereo microscope. The alimentary canal was obtained anatomically and Transmission Electron Microscope) was used in examining the stained sections.

RESULTS

Based on the nonhatching eggs produced by irradiated males' pupae, the values of effective doses were calculated. The effective doses ranged from 16 to 291 Gy for the ED25 - ED75. The sterility index reached 74.1% when irradiated with males by 291 Gy crossed with nonirradiated females and the adult emergence decreased to be 35.3%. The insecticidal potential of Bt-AgNPs on the 2nd and 4th larval instars was dose-dependent and its LC50 toxicity value was 0. 3 and 0. 4 mg/ml, respectively. The lethal concentration LC50 of the 2nd instar larvae increased the larval and pupal mortality to 55% and 44.4%, respectively, and reduced the adult emergence to be 55.6%. The combining effects of Bt-AgNPs with 291 Gy induced 100% pupae mortality and there was no adult emergence in F1 generation. Such effects also severed the ultrastructure deformity of the midgut of the 4th instar larvae after the two-day post-treatment.

CONCLUSIONS

The combining effects are recommended as an effective IPM program to control P. gossypiella by releasing sterile males (derived from pupae irradiated with 291 Gy) crossing with the normal females in the field, and reducing the fertility of the population to 31.2%. Subsequently, the resulted larvae treated with LC50 of Bt-AgNPs prevented the adult emergence and stopped the life cycle of P. gossypiella.

A review of the impact on the ecosystem after ionizing irradiation: wildlife population

PURPOSE

On 26 April 1986, reactor 4 at the Chernobyl power plant underwent a catastrophic failure leading to core explosions and open-air fires. On 11 March 2011, a combination of earthquake and tsunami led to a similar disaster at the Fukushima Daiichi power plant. In both cases, radioactive isotopes were released and contaminated the air, soil and water in a substantial area around the power plants. Humans were evacuated from the immediate regions but the wildlife stayed and continued to be affected by the ongoing high radiation exposure initially and later decayed amounts of fallout dusts with time. In this review, we will examine the significant effects of the increased radiation on vegetation, insects, fish, birds and mammals.

CONCLUSIONS

The initial intense radiation in these areas has gradually begun to decrease but still remains high. Adaptation to radiation is evident and the ecosystems have dynamically changed from the periods immediately after the accidents to the present day. Understanding the molecular mechanisms that allow the adaptation and recovery of wildlife to chronic radiation challenges would aid in future attempts at ecosystem remediation in the wake of such incidents.

Is developmental instability in chironomids a sensitive endpoint for testing uranium mine-affected sediments?

There is increasing interest in effects of radionuclides on non-human species, but methods for studying such effects are not well developed. The aims of the current study were to investigate the effects of uranium mine-affected sediments on non-biting midge Chironomus riparius and to compare sensitivity of different endpoints. The midge larvae were exposed in controlled laboratory conditions to sediments from two ponds downstream from an abandoned uranium mine and a reference pond not receiving water from the mining site. Quartz sand was used as an additional control. Developmental effects were assessed by evaluating emergence of adult midges, body mass, and fluctuating asymmetry (FA) in the length of wing upper vein. FA has been suggested to be a sensitive indicator of developmental instability, but the results of previous studies are inconsistent. In the present study, no difference in FA was observed between the treatment groups, but time to emergence was significantly delayed in the contaminated sediments. The approach used in this study (laboratory experiments with sediments from a contaminated site) avoids confounding due to uncontrolled environmental variables and adaptation to long-term contamination, which may mask effects on natural populations. Using this approach, we found no effects on FA of wing length. Time to emergence, in contrast, was found to be a more sensitive endpoint.

Midgut cells alteration in gamma-irradiated beetles (Blaps polycresta, Coleoptera: Tenebrionidae)

Abstract This study was conducted to examine the effect of gamma radiation on biological specimens. Thus, our concept is to clarify that exposure to accumulated dose of 0.2 Gy gamma rays (0.66 rad/Sec. dose rate) from Cs137 source induces cellular perturbations in the midgut epithelium of the F1 progeny of Blaps polycresta, therefore affecting nutrition and growth. Beetles were reared in laboratory conditions and the newly emerged adults were irradiated with the aforementioned dose. Histological and ultrastructure anomalies of midgut cells (digestive and regenerative cells) were observed by 72 h after radiation exposure to ensure that the cells will not return to control state. Retardation in the development of the F1 progeny was also noticed and beetles died through two weeks. In the light of these observations, biological tissue act as an indicator to the continuous exposure to environmental radiation.

A dose rate causes no fluctuating asymmetry indexes changes in silver birch (Betula pendula (L.) Roth.) leaves and Scots pine (Pinus sylvestris L.) needles in the Chernobyl Exclusion Zone

The assessment of the fluctuating asymmetry based on measurement of the parameters of left and right parts of silver birch (Betula pendula (L.) Roth.) leaves and relative sizes of pairs of Scots pine (Pinus sylvestris L.) needles from the Chernobyl Exclusion Zone (ChEZ) was carried out. Twelve samples of both birch leaves and pairs of needles were collected from 10 trees at 5 sites in the Chernobyl Exclusion Zone and also at one control site located outside the ChEZ. Values of gamma dose rate in the air varied between the sites from 0.1 to 40 μGy h^-1. Activity concentrations of ⁹⁰Sr and ¹³⁷Cs in the birch leaves varied over the range of 0.9÷2460 kBq kg^-1 and 0.1÷339 kBq·kg^-1 (DW), respectively. In addition to the above, in the Scots pine needles, these ranges were 0.7 ÷1970 kBq kg^-1f for ⁹⁰Sr and 0.1÷78 kBq kg^-1 (DW) for ¹³⁷Cs. From the values of the radionuclides activity concentrations in the plants, the internal dose rate is estimated to be in the range of 0.1 ÷ 274 μGy h^-1. The main sources of the internal dose rate were radiation of ⁹⁰Sr and ⁹⁰Y. Indices of fluctuating asymmetry of silver birch leaves and Scots pine needles varied over the range of 0.048 ± 0.007 ÷ 0.060 ± 0.009 and 0.014 ± 0.002 ÷ 0.018 ± 0.002, respectively, and did not statistically differ for all experimental sites. The indices also did not depend on the external or internal dose rate of ionizing radiation for plants. The above findings seem to be consistent with other research effort in terms of understanding the response of organisms to chronic pollutant exposure and the long-term effects of large scale nuclear accidents.

Ultrastructure alterations induced by gamma irradiation in spermiogenesis of the ground beetle, Blaps sulcata: reference to environmental radiation protection

Ultrastructure alterations in spermiogenesis of the ground beetle, Blaps sulcata (Coleoptera: Tenebrionidae) were studied in normal adult males and in two male groups irradiated by gamma rays of 3 and 16 μSv/h dose rate. Ultrastructure examination of irradiated sperms revealed many alterations both in the head and in the flagellum regions of mature sperm. Alterations of the head region included nuclei with uncondensed chromatin materials and irregular nuclear envelope. Abnormal flagella contained malformed mitochondrial derivatives and damaged axonemes in addition to the absence of accessory bodies. Bi- and multi-flagellate sperms (with two, three, and four axonemes) were the most common alterations. Sperm cells with residual bodies were also obtained. Agglutinated sperms and sperms with enlarged and/or vacuolated cytoplasm were common. Sperm abnormalities were more pronounced in males irradiated by 16 μSv/h dose rate than those irradiated by 3 μSv/h. Spermiogenesis alterations induced by irradiation of B. sulcata may be used as a monitoring model for predicting the effects of environmental radioactivity.

Geographic variation in wing size and shape of the grasshopper Trilophidia annulata (Orthoptera: Oedipodidae): morphological trait variations follow an ecogeographical rule

A quantitative analysis of wing variation in grasshoppers can help us to understand how environmental heterogeneity affects the phenotypic patterns of insects. In this study, geometric morphometric methods were used to measure the differences in wing shape and size of Trilophidia annulata among 39 geographical populations in China, and a regression analysis was applied to identify the major environmental factors contributing to the observed morphological variations. The results showed that the size of the forewing and hindwing were significantly different among populations; the shape of the forewing among populations can be divided into geographical groups, however hindwing shape are geographical overlapped, and populations cannot be divided into geographical groups. Environmental PCA and thin-plate spline analysis suggested that smaller individuals with shorter and blunter-tip forewings were mainly distributed in the lower latitudes and mountainous areas, where they have higher temperatures and more precipitation. Correspondingly, the larger-bodied grasshoppers, those that have longer forewings with a longer radial sector, are distributed in contrary circumstances. We conclude that the size variations in body, forewing and hindwing of T. annulata apparently follow the Bergmann clines. The importance of climatic variables in influencing morphological variation among populations, forewing shape of T. annulata varies along an environmental gradient.

Are Organisms Adapting to Ionizing Radiation at Chernobyl?

Numerous organisms have shown an ability to survive and reproduce under low-dose ionizing radiation arising from natural background radiation or from nuclear accidents. In a literature review, we found a total of 17 supposed cases of adaptation, mostly based on common garden experiments with organisms only deriving from typically two or three sampling locations. We only found one experimental study showing evidence of improved resistance to radiation. Finally, we examined studies for the presence of hormesis (i.e., superior fitness at low levels of radiation compared with controls and high levels of radiation), but found no evidence to support its existence. We conclude that rigorous experiments based on extensive sampling from multiple sites are required.

Ingestional and transgenerational effects of the Fukushima nuclear accident on the pale grass blue butterfly

One important public concern in Japan is the potential health effects on animals and humans that live in the Tohoku-Kanto districts associated with the ingestion of foods contaminated with artificial radionuclides from the collapsed Fukushima Dai-ichi Nuclear Power Plant. Additionally, transgenerational or heritable effects of radiation exposure are also important public concerns because these effects could cause long-term changes in animal and human populations. Here, we concisely review our findings and implications related to the ingestional and transgenerational effects of radiation exposure on the pale grass blue butterfly, Zizeeria maha, which coexists with humans. The butterfly larval ingestion of contaminated leaves found in areas of human habitation, even at low doses, resulted in morphological abnormalities and death for some individuals, whereas other individuals were not affected, at least morphologically. This variable sensitivity serves as a basis for the adaptive evolution of radiation resistance. The distribution of abnormality and mortality rates from low to high doses fits well with a Weibull function model or a power function model. The offspring generated by morphologically normal individuals that consumed contaminated leaves exhibited high mortality rates when fed contaminated leaves; importantly, low mortality rates were restored when they were fed non-contaminated leaves. Our field monitoring over 3 years (2011-2013) indicated that abnormality and mortality rates peaked primarily in the fall of 2011 and decreased afterwards to normal levels. These findings indicate high impacts of early exposure and transgenerationally accumulated radiation effects over a specific period; however, the population regained normality relatively quickly after ∼15 generations within 3 years.

Spatiotemporal abnormality dynamics of the pale grass blue butterfly: three years of monitoring (2011-2013) after the Fukushima nuclear accident

Background

Long-term monitoring of the biological impacts of the radioactive pollution caused by the Fukushima nuclear accident in March 2011 is required to understand what has occurred in organisms living in the polluted areas. Here, we investigated spatial and temporal changes of the abnormality rate (AR) in both field-caught adult populations and laboratory-reared offspring populations of the pale grass blue butterfly, Zizeeria maha, which has generation time of approximately one month. We monitored 7 localities (Fukushima, Motomiya, Hirono, Iwaki, Takahagi, Mito, and Tsukuba) every spring and fall over 3 years (2011–2013).

Results

The adult ARs of these localities quickly increased and peaked in the fall of 2011, which was not observed in non-contaminated localities. In the offspring generation, the total ARs, which include deaths at the larval, prepupal, and pupal stages and morphological abnormalities at the adult stage, peaked either in the fall of 2011 or in the spring of 2012, with much higher levels than those of the parent field populations, suggesting that high incidence of deaths and abnormalities might have occurred in the field populations. Importantly, the elevated ARs of the field and offspring populations settled back to a normal level by the fall of 2012 and by the spring of 2013, respectively. Similar results were obtained not only in the spatiotemporal dynamics of the number of individuals caught per minute but also in the temporal dynamics of the correlation coefficient between the adult abnormality rate and the ground radiation dose or the distance from the Power Plant.

Conclusions

These results demonstrated an occurrence and an accumulation of adverse physiological and genetic effects in early generations, followed by their decrease and leveling off at a normal level, providing the most comprehensive record of biological dynamics after a nuclear accident available today. This study also indicates the importance of considering generation time and adaptive evolution in evaluating the biological impacts of artificial pollution in wild organisms.

Electronic supplementary material

The online version of this article (doi:10.1186/s12862-015-0297-1) contains supplementary material, which is available to authorized users.