Effects of land‐use changes on ecosystem services: decrease in ant predation in human‐dominated landscapes in central Brazil

Anthropogenic disturbances often affect the abundance and diversity of ants (Hymenoptera: Formicidae) but relatively few studies have explored the implications of such changes on the ecosystem services mediated by these insects. Here, we evaluated how the transformation of Cerrado savanna habitats into crop plantations affects the abundance, diversity, and the predatory activity of ants. A survey of the ant faunas foraging above‐ and belowground was performed in six crop and six non‐crop (i.e., native vegetation) sites. Above‐ and belowground rates of ant predation were estimated at these same sites using mealworms, Tenebrio molitor L. (Coleoptera: Tenebrionidae), as baits, simulating crop herbivores. Belowground predation rates were significantly greater in the non‐crop sites, despite the lack of difference in overall abundance and species richness of ants foraging belowground between the crop vs. non‐crop sites. In contrast, we did not detect any significant difference in aboveground predation rates between crop vs. non‐crop sites even though there were significantly more species of ants foraging aboveground in the non‐crop sites. Army ants (subfamily Dorylinae) were the main predatory species belowground, and their abundance was significantly greater in non‐crop sites. In contrast, the main predators aboveground were omnivore ants of the genera Pheidole and Solenopsis, which had similar abundances in the crop and non‐crop sites. Overall, our results indicate that transformation of native Cerrado habitats into crop plantations reduces the abundance of some important predatory species, notably those that forage belowground, and this may negatively affect the potential for ants to provide pest control services in agroecosystems.     

土壤中辣椒疫霉分离方法的研究与量化测定

从杭州、西安、广州及武汉等辣椒病田分别采集土样 ,室内晾干研碎后 ,用选择性培养基 ,采用土壤稀释平板法和组织诱饵法分离辣椒疫霉 (PhytophthoracapsiciLeonian) ,并对土壤中辣椒疫霉的密度进行量化处理。结果表明 ,利用选择性燕麦培养基 ,采用土壤稀释平板法可分离获得大量的辣椒疫霉菌株 ,而且辣椒连作田的辣椒疫霉菌密度高于轮作田。组织诱饵法试验结果表明 ,辣椒叶片诱集效果最好 ,其次是辣椒果实。     

Distribution,occurrence and characterization of entomopathogenic fungi in agricultural soil in the Palestinian area

The occurrence of entomopathogenic fungi was investigated in irrigated vegetable fields and citrus orchards soils, over a nine-month period (April-December 1999),using the Galleria bait method (GBM). Entomopathogenic fungi were found to occur in 33.6% of the soil samples studied, with positive samples yielding 70 fungal isolates, belonging to 20 species from 13 genera. Conidiobolus coronatus was the most frequent and abundant entomopathogenic species recovered, comprising 31.4% of the total number of isolates. Soil pH, soil moisture content and the geographical location had minor or no effect on the isolation of entomopathogenic fungi in the fields studied. On the other hand, organic matter content of soil, and vegetation type were found to significantly affect the occurrence of entomopathogenic fungi in soil habitats, with orchard fields yielding larger numbers of isolates than vegetable fields. Using Koch's postulates the pathogenicity of fungal isolates to Galleria larvae was found to range from 16–100% (mortality rate). Isolates of C. coronatus proved to be the most virulent isolates recovered. The effect of media and temperature on mycelial growth rate, conidial production and conidial germination of six entomopathogenic fungal species (C. coronatus, Entomophaga grylli, Erynia castrans, Hirsutella jonesii, Paecilomyces farinosus and Sporodiniella umbellata) was also studied. Mycelial growth rate, spore production and spore germination were significantly affected by media, temperature and isolates. In view of the present results, C. coronatus appears to be a good candidate for pest control in agricultural soils, as it has a wide tolerance to agricultural practices, has frequently been isolated from both vegetable and orchard fields, and is characterized by high mycelial growth rate, conidial production and conidial germination.This revised version was published online in October 2005 with corrections to the Cover Date.     

基于GC-IMS技术的不同红火蚁监测诱饵的风味成分分析

探讨不同红火蚁Solenopsis invicta Buren监测诱饵的风味成分,以期获得优化诱饵配方的科学依据。本文采用顶空气相色谱-离子迁移谱法分析不同红火蚁监测诱饵在60℃下的气味指纹图谱,并通过主成分分析法分析其风味物质的差异。结果共鉴定出93个信号峰和87种挥发性化合物,载体物质(CK)中具有较高强度峰的化合物包括3种苯、2种醇、3种酮、2种酯、4种醛、1种呋喃和1种烯;自主配制的诱饵(JR、ZR、JZ)的风味组成相似,较高强度峰的化合物包括2种醇、1种酸、12种醛和1-8桉叶素等;市售火腿肠(HT)中的3种烯、10种酮、1种苯、5种醛、1种呋喃、3种醚、7种醇和4种酯是具有较高强度峰的化合物。主成分分析表明,CK、HT与自主研发的诱饵聚集距离较远,三者均单独聚为一类,相互风味成分区别较大。综上所述,JR、ZR和JZ诱饵中醛类物质较多,而HT中酮类与醇类物质较为丰富。上述诱饵的风味成分分析结果能为研发精准高效的红火蚁监测专用诱饵提供重要信息。     

转Cry1Ac抗虫棉对土壤虫生真菌群落的影响

利用大蜡螟Galleria mellonella L.诱菌法对转Cry1Ac抗虫棉GK-12及其亲本棉花SM-3的根系区域土壤的虫生真菌种类和数量进行监测,评价转Cry1Ac基因对棉田土壤虫生真菌的影响。实验结果显示:检测到的虫生真菌种类,在转基因棉GK-12及其亲本棉SM-3之间无显著差异,均为球孢白僵菌(Beauveria bassiana)和金龟子绿僵菌(Metarhizium anisopliae);在棉花开花初期、盛花期、结铃期或吐絮期,土壤虫生真菌数量在抗虫棉GK-12和亲本SM-3之间存在显著的差异,其他生育期无显著差异;在距棉花主根不同距离(5 cm\15 cm\25 cm)的区域,土壤虫生真菌数量和种类在抗虫棉GK-12和亲本SM-3之间无显著差异。     

人FAM92A1基因诱饵表达质粒的构建与鉴定

目的 构建人FAM92A1基因（hFAM92A1）的诱饵表达质粒pGBKT7-hFAM92A1并检测其蛋白表达、毒性和自激活作用.方法 PCR扩增hFAM92A1的基因编码序列并克隆入诱饵表达载体pGBKT7中,酶切和测序鉴定后,转化到酵母AHl09细胞中,Western印迹检测诱饵蛋白表达情况,同时检测诱饵蛋白的毒性和自激活作用.结果 成功构建FAM92A1基因的诱饵表达质粒pGBKT7-hFAM92A1,测序结果正确.Western印迹实验证实酵母细胞高表达诱饵蛋白hFAM92A1,诱饵蛋白没有自激活作用.结论 构建的诱饵表达质粒pGBKT7-hFAM92A1可用于下一步酵母双杂交系统实验,为进一步研究hFAM92A1功能奠定了基础.     

Intraspecific differences in bacterial responses to modelled reduced gravity

AIMS: Bacteria are important residents of water systems, including those of space stations which feature specific environmental conditions, such as lowered effects of gravity. The purpose of this study was to compare responses with modelled reduced gravity of space station, water system bacterial isolates with other isolates of the same species. METHODS AND RESULTS: Bacterial isolates, Stenotrophomonas paucimobilis and Acinetobacter radioresistens, originally recovered from the water supply aboard the International Space Station (ISS) were grown in nutrient broth under modelled reduced gravity. Their growth was compared with type strains S. paucimobilis ATCC 10829 and A. radioresistens ATCC 49000. Acinetobacter radioresistens ATCC 49000 and the two ISS isolates showed similar growth profiles under modelled reduced gravity compared with normal gravity, whereas S. paucimobilis ATCC 10829 was negatively affected by modelled reduced gravity. CONCLUSIONS: These results suggest that microgravity might have selected for bacteria that were able to thrive under this unusual condition. These responses, coupled with impacts of other features (such as radiation resistance and ability to persist under very oligotrophic conditions), may contribute to the success of these water system bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Water quality is a significant factor in many environments including the ISS. Efforts to remove microbial contaminants are likely to be complicated by the features of these bacteria which allow them to persist under the extreme conditions of the systems.     

Identification and characterization of bacterial isolates from the Mir space station

Twenty bacterial isolates (supplied by NASA) from the Mir space station water system were identified using Vitek GNI+ test card, API 20NE, and 16S rRNA gene sequencing. The identification of only one isolate agreed among the three techniques. The utility of the API 20NE and Vitek GNI+ test card approaches for identifying these isolates was Limited. Although 16S rRNA gene sequencing effectively identified many of the bacteria to the genus level, 74% of the isolates could not be identified to the species level. Isolates were also characterized based on motility and hydrophobicity. About 40% of the isolates were motile and four isolates were hydrophobic, suggesting that many of the bacteria have the potential to colonize surfaces and form biofilms. These findings demonstrate the difficulties in identifying bacteria from some environments to the species level and have implications for determining the risks of contamination in water systems of space shuttles and stations.     

Peak season plant activity shift towards spring is reflected by increasing carbon uptake by extratropical ecosystems

Climate change is lengthening the growing season of the Northern Hemisphere extratropical terrestrial ecosystems, but little is known regarding the timing and dynamics of the peak season of plant activity. Here, we use 34‐year satellite normalized difference vegetation index (NDVI) observations and atmospheric CO₂ concentration and δ¹³C isotope measurements at Point Barrow (Alaska, USA, 71°N) to study the dynamics of the peak of season (POS) of plant activity. Averaged across extratropical (>23°N) non‐evergreen‐dominated pixels, NDVI data show that the POS has advanced by 1.2 ± 0.6 days per decade in response to the spring‐ward shifts of the start (1.0 ± 0.8 days per decade) and end (1.5 ± 1.0 days per decade) of peak activity, and the earlier onset of the start of growing season (1.4 ± 0.8 days per decade), while POS maximum NDVI value increased by 7.8 ± 1.8% for 1982–2015. Similarly, the peak day of carbon uptake, based on calculations from atmospheric CO₂ concentration and δ¹³C data, is advancing by 2.5 ± 2.6 and 4.3 ± 2.9 days per decade, respectively. POS maximum NDVI value shows strong negative relationships (p < .01) with the earlier onset of the start of growing season and POS days. Given that the maximum solar irradiance and day length occur before the average POS day, the earlier occurrence of peak plant activity results in increased plant productivity. Both the advancing POS day and increasing POS vegetation greenness are consistent with the shifting peak productivity towards spring and the increasing annual maximum values of gross and net ecosystem productivity simulated by coupled Earth system models. Our results further indicate that the decline in autumn NDVI is contributing the most to the overall browning of the northern high latitudes (>50°N) since 2011. The spring‐ward shift of peak season plant activity is expected to disrupt the synchrony of biotic interaction and exert strong biophysical feedbacks on climate by modifying the surface albedo and energy budget.     

Toxicity of fipronil to German and American cockroaches

Topical and oral toxicity of fipronil, compared to chlorpyrifos, was determined for the German cockroach, Blattella germanica (L.), and American cockroach, Periplaneta americana (L.). Fipronil and Combat bait matrices were evaluated for their attractancies to both species. In the topical toxicity tests, LD50's of fipronil, at 72 h after topical application, were 0.03 and 0.02 µg/g for adult B. germanica and P. americana, respectively. Fipronil was significantly more toxic than topically applied chlorpyrifos (LD50's were 0.06 and 0.16 µg/g for B. germanica and P. americana, respectively). The oral toxicity of fipronil and chlorpyrifos in Petri dish experiments, against both species, was affected by stage (for B. germanica), diet concentration, and feeding assay. Fipronil caused higher mortality of B. germanica than chlorpyrifos in two feeding assays (continuous and abbreviated). Both compounds were equally toxic to adult males of P. americana at all rates. Fipronil caused higher nymphal mortality than chlorpyrifos 48–72 h after exposure in both feeding assays. In large population chamber tests, fipronil bait was more effective and faster in killing P. americana than Raid and Combat. LT50's were 0.8, 2.4, and 7.6 d for fipronil, Raid (a.i. = chlorpyrifos), and Combat (a.i. = hydramethylnon) baits, respectively. Mortality reached 96.5, 93.4, and 84.6%, respectively, at the end of the 14 d test. In the bait attractancy tests, both strains of B. germanica were attracted similarly to fipronil and Combat bait matrices. P. americana were attracted more to fipronil than to Combat bait matrix or to other alternative foods.