Phytotoxicity on cotton ex-plants of an 18.5 kDa protein from culture filtrates of Verticillium dahliae

A phytotoxic protein that evokes the typical symptoms of Verticillium wilt disease in seedlings of Gossypium hirsutum L. (Upland cotton) was isolated from culture filtrates of Verticillium dahliae. The protein was purified by ammonium sulfate precipitation, Sephadex-G100 fractionation, and native PAGE. The 18.5 kDa protein, designated VD18.5, appears to be a single subunit protein with an isoelectric point between 3 and 5. VD18.5 induces symptoms of leaf dehydration, chlorosis, necrosis and stem discoloration in seedlings of the disease susceptible cotton cultivar Siokra 1–4. The LD₅₀ of VD18.5 on protoplasts of Siokra 1–4 was 18 μg mL⁻¹. VD18.5 had no noticeable effect on Pima S-7, which is a disease resistant cultivar. Phytotoxic activity was partially destroyed at high temperature and was abolished by digestion with proteinase K. Mass spectrometry fingerprinting and protein sequence data from VD18.5 yielded no significant matches when submitted to the Mascot search engine and NCBI non-redundant protein databases, respectively. These results suggest that VD18.5 is a novel protein that may be involved in the development of some of the symptoms associated with Verticillium wilt disease in the cotton plant.     

十种常用农药与球孢白僵菌的生物学相容性

球孢白僵菌孢子粉与10种常用农药相容性的测定结果显示,随着孢子浓度上升,所试农药对孢子的抑制作用均有不同程度的增强。在1/10田间常规使用浓度下,百菌清和代森锰锌均能抑制或杀死孢子(萌发率<1％)。除阿维菌素外,所有杀虫剂均与白僵菌孢子相容,在常规使用浓度的10倍稀释液中孢子萌发率达90％以上。吡虫啉、蚜虱灵、灭多威和氟虫腈与孢子的相容性最好,其中吡虫啉和蚜虱灵对孢子萌发率的影响不明显随药剂浓度的变化而变化,即使在田间常规使用浓度下孢子萌发率也在95％以上,而阿维菌素与白僵菌的相容性极差。因此,应用白僵菌制剂防治害虫,选择生物学相容性好的农药以低剂量与白僵菌制剂混用,既可使菌剂增效,又可大幅度降低化学药剂用量。     

多杀菌素等新杀虫剂对粘虫的杀虫活性

浸叶法证明，多杀菌素(spinosad)、乙酰氨基阿维菌素和虫螨腈比阿维菌素对粘虫表现出更高的杀虫活性。其杀虫活性分别比阿维菌素高5倍、8倍和3．7倍。     

Soil conditions and land use intensification effects on soil microbial communities across a range of European field sites

Intensive land use practices necessary for providing food and raw materials are known to have a deleterious effect on soil. However, the effects that such practices have on soil microbes are less well understood. To investigate the effects of land use intensification on soil microbial communities we used a combined T-RFLP and pyrosequencing approach to study bacteria, archaea and fungi in spring and autumn at five long term observatories (LTOs) in Europe; each with a particular land use type and contrasting levels of intensification (low and high). Generally, due to large gradients in soil variables, both molecular methods revealed that soil microbial communities were structured according to differences in soil conditions between the LTOs, more so than land use intensity. Moreover, variance partitioning analysis also showed that soil properties better explained the differences in microbial communities than land use intensity effects. Predictable responses in dominant bacterial, archaeal and fungal taxa to edaphic conditions (e.g. soil pH and resource availability) were apparent between the LTOs. Some effects of land use intensification at individual field sites were observed. However, these effects were manifest when land use change affected soil conditions. Uniquely, this study details the responses of different microbial groups to soil type and land use intensification, and their relative importance across a range of European field sites. These findings reinforce our understanding of drivers impacting soil microbial community structure at both field and larger geographic scales.     

Response of the soil fungal community to multi-factor environmental changes in a temperate forest

Both environmental and climatic changes are known to influence soil microbial biomes in terrestrial ecosystems. However, there are limited data defining the interactive effects of multi-factor environmental disturbances, including N-deposition, precipitation, and air temperature, on soil fungal communities in temperate forests. A 3-year outdoor pot experiment was conducted to examine the temporal shifts of soil fungal communities in a temperate forest following N-addition, precipitation and air temperature changes. The shifts in the structure and composition of soil fungal communities were characterized by denaturing gradient gel electrophoresis and DNA sequencing. N-addition regimen induced significant alterations in the composition of soil fungal communities, and this effect was different at both higher and lower altitudes. The response of the soil fungal community to N-addition was much stronger in precipitation-reduced soils compared to soils experiencing enhanced precipitation. The combined treatment of N-addition and reduced precipitation caused more pronounced changes in the lower altitude versus those in the higher one. Certain fungal species in the subphylum Pezizomycotina and Saccharomycotina distinctively responded to N fertilization and soil water control at both altitudes. Redundancy discrimination analysis showed that changes in environmental factors and soil physicochemical properties explained 43.7% of the total variability in the soil fungal community at this forest ecosystem. Variations in the soil fungal community were significantly related to the altitude, soil temperature, total soil N content (TN) and pH value (P < 0.05). We present evidence for the interactive effects of N-addition, water manipulation and air temperature to reshape soil fungal communities in the temperate forest. Our data could provide new insights into predicting the response of soil micro-ecosystem to climatic changes.     

Being exposed to low concentrations of pirimiphos-methyl and chlorfenapyr has detrimental effects on the mobility of Trogoderma granarium

BACKGROUND

Sublethal effects of insecticides may negatively affect several biological and behavioral traits of insects. The lethal effects of pirimiphos-methyl and chlorfenapyr have been previously showed on Trogoderma granarium, but little knowledge is available about their sublethal effects at low concentrations on both sexes. Herein, the sublethal effects of pirimiphos-methyl and chlorfenapyr on the mobility of T. granarium males and females were investigated.

RESULTS

Lethal concentration (LC) values of pirimiphos-methyl and chlorfenapyr were lower for T. granarium females than males. LC values on males were LC₁₀ = 0.000788 and 0.00139 mg active ingredient (a.i.) cm⁻², LC₃₀ = 0.00350 and 0.00535 mg a.i. cm⁻², and LC₅₀ = 0.00986 and 0.0136 mg a.i. cm⁻² for pirimiphos-methyl and chlorfenapyr respectively. LC on females were LC₁₀ = 0.000704 and 0.00110 mg a.i. cm⁻², LC₃₀ = 0.00323 and 0.00428 mg a.i. cm⁻², and LC₅₀ = 0.00925 and 0.0110 mg a.i. cm⁻² for pirimiphos-methyl and chlorfenapyr respectively. The walking duration of beetles exposed to LC₃₀ of pirimiphos-methyl was significantly lower than the individuals exposed to LC₁₀ and LC₃₀ of both insecticides and control ones. Pirimiphos-methyl LC₃₀-exposed males remained more time on their back (101.7 s) than females (46.9 s), while the latter stayed immobile longer than males (381.7 s versus 371.9 s). The highest speed was recorded for control beetles (14.17 mm s⁻¹ females vs. 12.44 mm s⁻¹ males), while the lowest speed was observed in pirimiphos-methyl LC₃₀-treated males (8.36 mm s⁻¹) and females (9.66 mm s⁻¹).

CONCLUSIONS

Overall, males and females exposed to low concentrations of pirimiphos-methyl and chlorfenapyr showed reduced motility. This knowledge can be exploited further to unlock behavioral effects of insecticides for effective pest management programs in warehouses. © 2023 Society of Chemical Industry.