A switch of microbial flora coupled with ontogenetic niche shift in Leptinotarsa decemlineata.

BackgroundLargemouth bronze gudgeon (Coreius guichenoti) is of economic importance in China, distributed in upstream regions of the Yangtze River in China. But it has recently dramatically declined and is close to elimination. However, there is little knowing about the character of its intestinal microbiota. This study was conducted to elucidate the intestinal microbiota of wild largemouth bronze gudgeon with different body weight and gender.ResultsThirty wild largemouth bronze gudgeon were measured for body length and body weight, and identified for male and female according to gonadal development, and thereafter the intestinal microbiota’s were assessed by MiSeq sequencing of 16S rRNA genes. The results revealed that phyla Proteobacteria and Tenericutes were dominant in wild largemouth bronze gudgeon intestine independent of the body weight. Shannon’s and Inverse Simpson’s diversity indexes were significant (P < 0.05) different between male and female fish. The phylum profile in the intestine of male fish revealed that phylum Proteobacteria was dominant, in contrast to female fish where five phyla Tenericutes, Proteobacteria, Firmicutes, Fusobacteria and Spirochaetes were dominant. The genus profile revealed that genera Shewanella and Unclassified bacteria were dominant in male fish, while genus Mycoplasma was dominant in female fish.ConclusionsOur results revealed that the intestinal microbial community of wild largemouth bronze gudgeon was dominated by the phyla Proteobacteria and Tenericutes regardless of the different body weight, but the communities are significant different between male and female fish. These results provide a theoretical basis to understand the biological mechanisms relevant to the protection of the endangered fish species.

Objective The citrus longhorned beetle, Anoplophora chinensis, is an important trunk borer and has an extensive host range.It is difficult to control the beetle as it is hidden in the truck and has a long larvae duration. A method for rearing the beetle is required to underpin studies of the biology and management, therefore the objective of this study was to compare insect performance on candidate artificial diets and temperature regimes. Method A. chinensis was reared on four different diets over three successive generations and the effect of different temperature regimes on development of A. chinensis was investigated. Result The results showed that A. chinensis was able to complete life cycle on the four artificial diets but with different pupation rates and emergence rates. Two diets (Diet A and D) based on sawdust of Casuarina equisetifolia and wheat bran gave good performance over 3 generations of A. chinensis. Pupation rates over three generations on Diet A were 100%, 90% and 95%, respectively and emergence rates were 100%, 83% and 90%, respectively. Pupation rates on Diet D were 87%, 78% and 87%, respectively and emergence rates were 87%, 67% and 80%, respectively. In addition,the rearing with these two diets showed that pupation and adult emergence rates were higher and more synchronized under fluctuating (all completed in April to May, the times of pupation and emergence were consistent with those observed in field) rather than constant temperatures. The times of pupation and emergence at constant temperatures were extended and highly variable. The larval weight gain over time was assessed under fluctuating and constant temperatures, showing that larval weight peaked at week 16-20 depending on diet, and then declined until pupation or death. The larval weight under fluctuating temperatures peaked at week 16 (late November) and larval weights on Diet D (2.077 g) were significantly higher than on Diet A (1.685 g). Under constant temperature (28℃), the larval weight peaked at week 16 on Diet D and peaked at week 20 on Diet A. Conclusion A. chinensis larvae can complete life cycle with high pupation and emergence rates, when being successively reared on Diet A and D. Temperature conditions affect the determination of the timing of A. chinensis pupation and adult emergence. Although a larval chill period is not essential, it does increase the pupation rate and synchronize development time. These findings provide a valuable resource for culturing A. chinensis, specifically by identifying suitable artificial diets and the temperature effects on larval development.The results could also provide reference for rearing other cerambycid.

Highlights A pneumatic prototype machine to control the Colorado potato beetle (CPBs) was successfully designed, built, and tested in a potato field under real conditions. The pneumatic prototype machine is effective in dislodging CPB larvae from potato plants. ABSTRACT . The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is a real threat to potato crops when left uncontrolled. This insect pest is hard to control because it develops resistance to most chemical insecticides. To date, several alternatives including chemical, biological, and physical methods have been used to control CPB populations but have proven to be ineffective on their own. So far, the most reliable method at short and medium scales has been the use of chemicals, i.e., spraying insecticides onto potato plants at regular intervals throughout the life cycle of the CPB. However, the overuse of chemicals due to the resistance developed by the CPB can lead to serious health and environmental problems. The use of a pneumatic method to control the CPB seems to be a viable alternative compared to the use of chemicals. For this purpose, this research focused on engineering a pneumatic control device that could allow farmers to reduce their reliance on chemical insecticides. A pneumatic prototype machine using positive air pressure to dislodge CPBs from potato plant foliage was designed and built at the Department of Soils and Agri-Food Engineering of Université Laval. This prototype was tested in the field using three airflow velocities (31, 35, and 38 m/s) and two travel speeds (5 and 6 km/h). The results indicated that the airflow velocity and travel speed have no significant impact on dislodging the CPB (p = 0.0548 and 0.7033, respectively). However, the interaction between airflow velocities and the development stages of the CPB had a significant effect on dislodging the CPB (p = 0.0194). Overall, the most adequate airflow velocity that resulted in removing most of the CPB larvae from potato leaves was 35 m/s. Obtained results indicate that this pneumatic prototype machine could be efficiently used to control the CPB. However, extensive testing is required to confirm obtained results and investigate the effects of the pneumatic control on both the potato plant growth and the yield compared to other control means. Keywords: Airflow velocity, Colorado potato beetle, Pneumatic control, Potato, Travel speed.

Diversity analyses of microbial communities in petroleum samples from Brazilian oil fields

The flight take-off frequency of adult Colorado potato beetles, Leptinotarsa decemlineata (Say), from potato plants, Solanum tuberosum L. 'Red Pontiac' at the bloom stage of development was 2.2-2.5-fold that of Colorado potato beetle from plants at the vegetative stage. Tests were conducted in a flight chamber over a period of 3 h. Prefeeding Colorado potato beetles for 48 h on potato plants at the bloom or at the vegetative stage before placing them into the flight chamber resulted in the same significantly higher flight take-off frequency from potato plants at the bloom stage than from plants at the vegetative stage. These results demonstrate that the factor in potato plants in bloom that stimulates the flight take-off of the Colorado potato beetle is independent of the feeding history of the beetles and begins acting only when the beetles are in the presence of the plant. According to these results, the dispersal of adult Colorado potato beetles from potato fields in bloom to younger potato fields with plants at the vegetative stage, previously reported in the literature, is at least partly explained by the effect of plant phenology on the frequency of flight take-off. Results confirm the value of planting potato fields of similar phenology over as wide an area as possible to reduce Colorado potato beetle dispersal between fields. Results also imply that staggering the planting dates of conventional potato refuge areas near Colorado potato beetle transgenic or conventionally resistant potato fields is a sound management practice, because it promotes the movement of wild beetles over to the adjacent younger resistant crops.

Toxicological effects of the fungal volatile compound 1-octen-3-ol against the red flour beetle, Tribolium castaneum (Herbst)

The diversity of 184 isolates from rhizosphere and bulk soil samples taken from the Ni hyperaccumulator Alyssum murale, grown in a Ni-rich serpentine soil, was determined by 16S rRNA gene analysis. Restriction digestion of the 16S rRNA gene was used to identify 44 groups. Representatives of each of these groups were placed within the phyla Proteobacteria, Firmicutes and Actinobacteria by 16S rRNA gene sequence analysis. By combining the 16S rRNA gene restriction data with the gene sequence analysis it was concluded that 44.6% (82/184) of the isolates were placed within the phylum Proteobacteria, among these 35.9% (66/184) were placed within the class α-Proteobacteria, and 20.7% (38/184) had 16S rRNA gene sequences indicative of bacteria within genera that form symbioses with legumes (rhizobia). Of the remaining isolates, 44.6% (82/184) and 5.4% (10/184) were placed within the phyla Actinobacteria and Firmicutes, respectively. No placement was obtained for a small number (10/184) of the isolates. Bacteria of the phyla Proteobacteria and Actinobacteria were the most numerous within the rhizosphere of A. murale and represented 32.1% (59/184) and 42.9% (79/184) of all isolates, respectively. The approach of using 16S rRNA gene sequence analysis in this study has enabled a comprehensive characterization of bacteria that predominate in the rhizosphere of A. murale growing in Ni-contaminated soil.

Plant communication via airborne volatile organic compounds is a widespread phenomenon by which volatile organic compounds from damaged plants boost herbivore resistance in receiver plants. This phenomenon has been studied only in a handful of crop species. We tested for communication between potato ( Solanum tuberosum ) plants in response to herbivory by the Colorado potato beetle, Leptinotarsa decemlineata . For this, we performed a greenhouse experiment with 15 potato varieties for which we caged pairs of plants (i.e., emitters and receivers) of the same variety. Half of the emitter plants were subjected to leaf damage by beetle larvae and the other half remained intact. We collected volatile organic compounds from emitter plants and estimated L. decemlineata damage on receivers. We found no evidence of quantitative (total production) or qualitative (compound composition) changes in volatile organic compound emissions due to beetle herbivory. In addition, the leaf damage treatment on emitters had no significant effect on receiver herbivore resistance, suggesting no communication between infested and non‐infested potato plants in response to Colorado potato beetle damage. Overall, this study provides baseline information on airborne signalling (or the lack of thereof) in potato plants which can inform subsequent work that identifies airborne volatiles with potentially strong effects on priming or defence induction.

HighlightsA prototype pneumatic machine used to control the Colorado potato beetle (CPB) had no effect on potato plant growth.Yields in pneumatic treatment plots were comparable to those of control plots treated with a biological insecticide.Pneumatic control of the CPB could be an alternative to reduce reliance on chemical insecticides in potato fields.Abstract. The Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say), is the major insect pest of potato plants. Currently, the most effective method for controlling the CPB is to apply chemical insecticides throughout its lifecycle. However, the CPB has the ability to resist most chemical insecticides. Control of this insect pest has therefore become extremely difficult, prompting researchers to explore effective alternatives. The use of pneumatic methods to control the CPB is a promising alternative to chemical means. The objective of this study was to develop an effective pneumatic control method for the CPB to reduce the reliance on chemical insecticides in potato fields. In this context, a prototype pneumatic machine was designed and built. The prototype uses positive air pressure to dislodge CPBs from potato foliage, deposit them on the ground between the rows, and crush them. The effects of three airflow velocities (45, 50, and 55 m s-1) and two tractor travel speeds (5 and 6 km h-1) on CPB control, plant growth, and tuber yield were investigated in potato plots. Overall, the results showed no significant differences in yield between treatments (p = 0.3268), indicating that the yield of potato plants treated with the prototype was comparable to that of plants treated with a biological insecticide (Entrust). In addition, the prototype did not have any negative effects on plant growth. This suggests that the prototype could be safely and efficiently used in potato fields to control the CPB. The success of this innovative control method could greatly contribute to reducing the use of chemical insecticides to control the CPB. Keywords: Airflow velocity, Leptinotarsa decemlineata (Say), Pneumatic control, Potato, Travel speed.

Field experiments were designed to subject Superior potato plants to various levels of defoliation by the Colorado potato beetle (CPB)Leptinotarsa decemlineata (Say), Coleoptera: Chrysomelidae. Defoliation occurred during each of five consecutive plant growth periods and CPB population, plant leaf area, and tuber weight data were recorded for each period. A visual defoliation rating scheme provided an accurate estimate of actual potato plant leaf area of defoliated plants. Data generated from regression analysis demonstrated a significant dependence of leaf area on CPB numbers per plant during some plant growth periods, but numbers of CPB accounted for very little of the total variation in tuber weight. Plant leaf area was the most important independent variable in the tuber weight regression model.

With the ultimate aim of developing bioremediation technology that use the optimum bacterial community for each pollutant, we performed polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and phylogenetic analysis and identified communities of culturable bacteria in HgCl(2)- and trichloroethylene (TCE)-contaminated soil microcosms. PCR-DGGE band patterns were similar at 0 and 1 ppm HgCl(2), but changes in specific bands occurred at 10 ppm HgCl(2). Band patterns appearing at 10 and 100 ppm TCE were very different from those at 0 ppm. Phylogenetic analysis showed four bacterial groups in the HgCl(2)-contaminatied cultures: Firmicutes, Actinobacteria, Proteobacteria, and Bacteroidetes. Most high-density bands, decreased-density bands, and common bands were classified into the phyla Proteobacteria, Actinobacteria, and Firmicutes, respectively; the effects of HgCl(2) on culturable bacteria appeared to differ among phyla. Duganella violaceinigra [98.4% similarity to DNA Data Bank of Japan (DDBJ) strain], Lysobacter koreensis (98.2%), and Bacillus panaciterrae (98.6%) were identified as bacteria specific to HgCl(2)-contaminated soils. Bacteria specific to TCE-contaminated soils were distributed into three phyla (Firmicutes, Proteobacteria, and Actinobacteria), but there was no clear relationship between phylum and TCE effects on culturable bacteria. Paenibacillus kobensis (97.3%), Paenibacillus curdlanolyticus (96.3%), Paenibacillus wynnii (99.8%), and Sphingomonas herbicidovorans (99.4%) were identified as bacteria specific to TCE-contaminated soils. These bacteria may be involved in pollutant degradation.

Simple SummaryAn egg-larva endoparasitoid (Chelonus bifoveolatus) of fall armyworm (FAW) in Zambia was identified based on morphological and molecular characteristics. To assess the parasitism capabilities of C. bifoveolatus against FAW, we compared partial biological parameters parasitizing 0- to 2-day-old FAW eggs. Chelonus bifoveolatus successfully parasitized and developed on eggs in all tested samples. In addition, it had a higher parasitism rate, pupation rate, and emergence rate on 1-day-old FAW eggs, but shorter development time on 2-day-old FAW eggs. Eggs of all ages tested revealed that females to males sex ratio was nearly 1:1.The fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a migratory pest endemic, to tropical and subtropical regions of America. Biological control can effectively and sustainably control pests over a long period of time while reducing the frequency of pesticide use and ensuring the safety of agricultural produce. In our study, the egg-larval Chelonus species (Chelonus bifoveolatus) from parasitized eggs of Spodoptera frugiperda in Zambia were described and identified based on morphological and genetic characteristics. To evaluate the efficiency of C. bifoveolatus, their parasitism suitability on 0- to 2-day FAW eggs under laboratory conditions was compared. The results showed that C. bifoveolatus could accept all FAW eggs at 0-, 1- and 2-day-old age and complete development successfully. Significant differences were found among 0-, 1-, and 2-day-old host eggs with respect to egg-larva developmental duration of C. bifoveolatus, and the egg-larva developmental duration on 2-day-old eggs was significantly lower than those on 0- and 1-day-old eggs. No significant differences were observed in the parasitism, pupation, emergence, and female rates for C. bifoveolatus on various age eggs of FAW. Generally, the parasitism rate, pupal rate, and emergence rate at various ages of FAW eggs were higher than 90%, 75%, and 82%, respectively, and the longevity of female parasitoids was longer than male parasitoids, and the sex ratio of females to males was nearly 1:1. Our results indicate that C. bifoveolatus performed well on various ages of FAW eggs and is a potential biological control agent against FAW in Africa.

House fly larvae provide a prolific and sustainable source of proteins used in poultry and fish feed. Wheat bran is a superior diet for house fly larvae and has been widely investigated to exploit its potential in the food and feed area. Using Illumina MiSeq 16S rDNA sequencing, this study investigated the gut microbiota of house fly larvae feeding on wheat bran and the bacterial community in the wheat bran. The bacterial communities in the house fly larvae were dominated by the phyla Proteobacteria and Firmicutes. Enterobacteriaceae and Providencia were the predominant bacteria at the family and genus levels, respectively. Some bacteria in the phyla Actinobacteria, Proteobacteria, Bacteroidetes and Firmicutes may be transferred from the gut of house flies to the wheat bran during feeding and may be involved in degrading and utilizing polysaccharides in the cell wall of wheat bran. The significance of the gut microbiota of house fly larvae, their transferring and roles in degradation of wheat bran is discussed. These findings regarding the gut microbiota of house fly larvae will provide opportunities for research on the impact of microbial communities on poultry and fish.

Control of the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), with the entomopathogenic nematode Heterorhabditis marelata Liu and Berry (Nematoda: Heterorhabditidae) was examined in the laboratory and in potato fields in north central Oregon. This research tested the hypothesis that varying nitrogen fertilizer levels would affect foliar alkaloid levels, which would stress the host, and allow increased nematode reproduction and long‐term control of the CPB. Laboratory results indicated that nematodes tended to reproduce more readily in CPB fed on potato plants with high levels of fertilizer. Field trials tested CPB population responses to four treatments: application of nematodes vs. no nematodes, with application of low vs. high rates of nitrogen fertilizer. The higher nitrogen application rate increased field foliar levels of the alkaloids solanine by 35%, and chaconine by 41% over the season. Nematodes were applied twice during the season, causing a 50% reduction in adult CPB populations, and producing six times as many dead prepupae in nematode‐treated soil samples as in the untreated samples. However, no reproducing nematodes were found in the 303 dead prepupae and pupae collected from nematode‐treated plots. Nitrogen fertilizer levels, and their related alkaloid levels, did not affect nematode infection rates or reproduction in the field. Foliar alkaloid levels of plants from the growth chamber were 3–6‐fold as high as those in the field, which may explain the variation in nematode response to nitrogen applications to host plants of the CPB. Heterorhabditis marelata is effective for controlling CPB in the field, and does not have negative non‐target effects on one of the most common endemic CPB control agents, Myiopharus doryphorae (Riley) (Diptera: Tachinidae), but the low rate of nematode reproduction cannot be manipulated through alkaloid stress to the beetle. Until H. marelata can be mass‐produced in an inexpensive manner, it will not be a commercially viable control for CPB.

A comprehensive study has been carried out, and a quantitative and qualitative characteristic of the soil prokaryotic community of zonal Ferralsol and intrazonal Fluvisol of Vietnam, as well as associated leaf litter and “suspended” soil from epiphytic ferns, has been given. The greatest number of bacteria, determined by the direct luminescence method, was associated with samples of Fluvisol, while the lengths of fungal and actinomycete mycelium were the largest in mountainous ferralitic soils. Bacteria of the genus Streptomyces, included in the saprotrophic bacterial complex of the studied substrates, make a significant contribution to the destruction of plant material. The bacteria of the phyla Firmicutes (80%) and Proteobacteria (15%) predominated in the prokaryotic community of the zonal red-yellow humus-ferrallitic soil, while the phyla Proteobacteria (51%) and Actinobacteria (38%) dominated in the sample of the “suspended” soil. The phyla Chloroflexi, Acidobacteria, Bacteroidetes, and Cyanobacteria were significantly less represented. With significant differences at the level of genera in the studied substrates, similar functional groups of microorganisms were identified: xenobiotic decomposers, nitrogen cycle bacteria, extremophiles, as well as bacteria that inhibit the growth of micromycetes. The metabolically active part of the prokaryotic community, represented by the phyla Proteobacteria, Actinobacteria, and Acidobacteria, was the highest in the “suspended” soil and the least active in the litter and horizon A of Ferralsol, which correlated with the high abundance of these phyla and the significant taxonomic diversity of bacteria in this locus. Functional genes (nifH and alkB) were detected in all studied substrates. The number of copies of functional genes was the highest in the “suspended” soil sample, which makes this locus promising for isolating strains with high biotechnological potential.