Response of N2O emission to straw retention under two contrasting paddy water conditions: a field experiment over rice–rice-fallow rotation

Paddy and Water Environment - Few studies are available on comprehensive impacts of straw retention and water regimes on nitrous oxide (N2O) emission from rice–rice-fallow rotation systems. A...     

Identification and Function Analysis of enolase Gene NlEno1 from Nilaparvata lugens (St?l) (Hemiptera:Delphacidae)

The enolase [EC 4.2.1.11] is an essential enzyme in the glycolytic pathway catalyzing the conversion of 2-phosphoglycerate (2-PGE) to phosphoenolpyruvate (PEP). In this study, a full-length cDNA encoding α-enolase was cloned from rice brown planthopper (Nilaparvata lugens) and is provisionally designated as NlEno1. The cDNA sequence of NlEno1 was 1,851 bp with an open reading frame (ORF) of 1,305 bp and encoding 434 amino acids. The deduced protein shares high identity of 80–87% with ENO1-like protein from Hemiptera, Diptera, and Lepidoptera speices. The NlEno1 showed the highest mRNA expression level in hemolymph, followed by fat body, salivary gland, ovaries and egg, and showed trace mRNA levels in testis. The mRNA of NlEno1 showed up-regulated level in virulent N. lugens population Mudgo, IR56 and IR42 when compared with TN1 population. Injection of double-stranded RNA (dsRNA) of NlEno1 into the adults significantly down-regulated the NlEno1 mRNA level along with decreased eggs and offspring. Moreover, injection of NlEno1-dsRNA decreased mRNA level of Vitellogenin (Vg) gene. These results showed that the NlEno1, as a key glycolytic enzyme, may play roles in regulation of fecundity and adaptation of N. lugens to resistant rice varieties.     

Geographic Variation of Diapause and Sensitive Stages of Photoperiodic Response in Laodelphax striatellus Fallén (Hemiptera: Delphacidae)

Large numbers of the small brown planthopper Laodelphax striatellus (Fallén) (Hemiptera: Delphacidae) occur in temperate regions, causing severe losses in rice, wheat, and other economically important crops. The planthoppers enter diapause in the third- or fourth-instar nymph stage, induced by short photoperiods and low temperatures. To investigate the geographic variation in L. striatellus diapause, we compared the incidence of nymphal diapause under various constant temperature (20 and 27°C) and a photoperiod of 4:20, 8:16, 10:14, 12:12, 14:10, and 16:8 (L:D) h regimes among three populations collected from Hanoi (21.02° N, 105.85° E, northern Vietnam), Jiangyan (32.51° N, 120.15° E, eastern China), and Changchun (43.89° N, 125.32° E, north-eastern China). Our results indicated that there were significant geographic variations in the diapause of L. striatellus. When the original latitude of the populations increased, higher diapause incidence and longer critical photoperiod (CP) were exhibited. The CPs of the Jiangyan and Changchun populations were ∼12 hr 30 min and 13 hr at 20°C, and 11 hr and 11 hr 20 min at 27°C, respectively. The second- and third-instar nymphs were at the stage most sensitive to the photoperiod. However, when the fourth- and fifth-instar nymphs were transferred to a long photoperiod, the diapause-inducing effect of the short photoperiod on young instars was almost reversed. The considerable geographic variations in the nymphal diapause of L. striatellus reflect their adaptation in response to a variable environment and provide insights to develop effective pest management strategies.     

Injury to apples and peaches at harvest from feeding by Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) nymphs early and late in the season

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive species that has become an important orchard pest in the Mid-Atlantic region of the US. Adults and nymphs feed on tree fruit. Feeding injury from adults has been characterized but the injury from nymphs has not been examined systematically. Since the four plant-feeding instars of H. halys (second through fifth) differ substantially in size, it is plausible that the effects of their feeding on fruit injury and injury expression may differ among them. We compared feeding injury at harvest from young nymphs (second plus third instars), older nymphs (fourth plus fifth instars), and adults that were caged on ‘Smoothee Golden’ apples and ‘Redhaven’ peaches in early June (peach and apple), late July (peach), and late August (apple). Individual apples and peaches were caged at fruit set and assigned to the following treatments (n = 28/treatment): 1) control (no H. halys), 2) young nymphs or 3) adults early in the season, and 4) young nymphs, 5) older nymphs or 6) adults later in the season. Fruit in each treatment were exposed to 3–4 young nymphs, two older nymphs or 1–2 adults placed in the cages for 96 h and evaluated for external and internal feeding injury within 36 h after harvest. No injury was recorded from unexposed peaches or apples. The percentage of injured fruit and number of injuries per fruit varied significantly among the exposed treatments. Early season feeding by young nymphs yielded the least injury to peaches and apples. In apples, the highest percentage of injured fruit and number of injuries per fruit were caused by late season feeding by adults. In peaches, early season adult feeding produced the highest percentage of injured fruit and injuries per fruit. More internal than external injury was recorded on peach and no such difference was observed on apple. The implications of these findings on H. halys management in fruit orchards are discussed.     

Considerations for the use of neonicotinoid pesticides in management of Bactericera cockerelli (Šulk) (Hemiptera: Triozidae)

Bactericera cockerelli is a pest on multiple solanaceous crop plants and is the sole vector for the bacteria Candidatus Liberibacter psyllaurous. When the pathogen is present, feeding by these psyllids results in ‘vein greening’ disease in peppers and tomatoes, and “zebra chip” disease in potatoes. Currently, management is based entirely on the application of pesticides, including two neonicotinoid compounds. Populations of B. cockerelli collected in southern Texas in 2006 and 2012 were examined for reduced susceptibility and behavioral responses to imidacloprid.Tests comparing imidacloprid and thiamethoxam demonstrated that both can reduce nymph numbers in the field, but retention and effective periods vary among application methods and compounds. In addition, imidacloprid and thiamethoxam are both sensitive to the amount of water applied during irrigation. Collectedly, these results suggest that imidacloprid is unlikely to be effective in controlling B. cockerelli in south Texas. Moreover, its use needs to be carefully considered in other locations even where resistance has not yet been detected. Finally, thiamethoxam may be useful, but careful attention must be paid to irrigation and rainfall level, application method, and timing of application.     

Some factors affecting the toxicity of poisons to the slug Deroceras reticulatum (Müller) (Pulmonata: Limacidae)

The toxicities of 52 phenolic and other chemicals to the grey field slug, Deroceras reticulatum (Müller 1774) (Mollusca: Pulmonata: Limacidae) were compared in laboratory tests. Stomach-poison activity was assessed by injecting measured amounts into the gut and contact-action activity by confining crawling slugs on coated glass plates. Chemical uptake into slugs was measured from aqueous solution and from a dry glass surface. Stomach-poison activity increased generally with substitution by groups increasing lipophilicity and acidity. Uptake was related to lipophilicity when slugs were immersed in aqueous solutions but not when slugs crawled on dry deposits. An expression was derived, using water solubilities and octanol/water partition coefficients, which correctly predicted uptake from an inert surface. The implications for developing chemical control methods for slugs in the field are discussed.     

Effects of the insecticide triazophos on the ultrastructure of the flight muscle of the brown planthopper Nilaparvata lugens Stål (Hemiptera: Delphacidae)

The brown planthopper (BPH), Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is a long-distance migratory insect pest in temperate eastern Asia and is a classical resurgent rice pest that is induced by insecticides. Knowledge of the effect of insecticides on the flight capacity of insects is needed to understand their migration, which may help to improve the management of insect pests. Our previous study demonstrated that some insecticides enhance the flight capacity of BPH. However, the effect of insecticides on the flight muscle of BPH is not well understood. Thus, the present study examined the effect of triazophos, a classical insecticide that induces the resurgence of BPH, on the ultrastructure of macropterous females using transmission electron microscopy. The results showed that the diameter of myofibrils one and two days after adult female emergence (DAE) following treatment with 40 ppm triazophos was significantly greater than that of the control, increasing by 31.4 and 21.5%, respectively. In addition, the length of the sarcomeres at two and three DAE was significantly greater than that of the control, increasing by 73.8 and 50.8%, respectively. The percentage of mitochondrial volume in the muscle fibres at one and two DAE was 146.2 and 67.7% greater than that of the control, respectively. These findings show that the mechanisms of triazophos-induced enhancement of the flight capacity of BPH involve changes in the ultrastructure of the flight muscle.     

Susceptibility of Louisiana and Florida populations of Spodoptera frugiperda (Lepidoptera: Noctuidae) to transgenic Agrisure®Viptera™ 3111 corn

In the United States, fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), is a target species of transgenic corn (Zea mays L.) expressing pyramided Bacillus thuringiensis proteins. In 2011, a total of 150 F₂ two-parent families of S. frugiperda were established using single-pair matings of feral individuals collected from three locations in Louisiana and Florida. The objective of this study was to determine the susceptibility of these field derived families of S. frugiperda to a pyramided Bt corn hybrid containing Agrisure^®Viptera™ 3111 traits. For each F₂ family, 96 neonates were assayed on leaf tissue of Agrisure^®Viptera™ 3111 corn in the laboratory. None of the 150 families survived for 7 days on leaf tissue of the Bt corn plants. The results demonstrate that the field populations of S. frugiperda collected from Louisiana and Florida were susceptible to the pyramided Bt corn product containing Agrisure^®Viptera™ 3111 traits. The data generated in this study can be used as baseline data for resistance monitoring.     

Sublethal effect of avermectin and acetamiprid on the mortality of different life stages of Brontispa longissima (Gestro) (Coleoptera: Hispidae) and its larvae parasitoid Asecodes hispinarum Bouček (Hymenoptera: Eulophidae)

The beneficial parasitoid Asecodes hispinarum Bouček plays an important role in integrated pest management (IPM) of the coconut leaf beetle, Brontispa longissima (Gestro), in China. A. hispinarum females parasitize 3rd to 4th instars B. longissima larvae. Hatched parasitoid larvae develop within the host, and parasitoid adults emerge through holes that they chew through the cuticle of the host. Although chemicals serve as the main short term control agents, the compatibility of biological and chemical control has never been investigated for this system. This study examined the responses of immature and adult B. longissima and its larval parasitoid A. hispinarum to avermectin and acetamiprid. Avermectin caused complete mortality of 2nd to 4th instar larvae, and of adults of B. longissima at 10, 15 and 2 d after treatment, respectively. However, 26.7% of the 2nd instar larvae, 55.3% of the 4th instar larvae, and 74%, of adult B. longissima were still alive 40 d after acetamiprid application. Following avermectin exposure, 17.5%, 9.2% and 23% of mummified B. longissima larvae contained viable adult parasitoids for the parasitoid egg, larva and pupa treatments, respectively, and the numbers of dead parasitoids per mummy were 3.3, 7.2 and 13.3 for the egg, larva and adult treatments, respectively. However, for acetamiprid treatment, 70–75.9% of mummified B. longissima larvae contained viable adult parasitoids in all three stage treatments, and the number of dead parasitoids per mummy was 2.8, 2 and 3.4 in egg, larva and adult treatments, respectively. This study showed that a sublethal dose of avermectin is more toxic than acetamiprid to B. longissima and A. hispinarum. Therefore, direct contact of the parasitoid with avermectin should be avoided when this insecticide is used to control B. longissima.     

Physiological and molecular responses of seedlings of an upland rice (‘Tung Lu 3’) to total submergence compared to those of a submergence-tolerant lowland rice (‘FR13A’)

Background

Understanding the responses of rice to environmental stresses such as unscheduled submergence is of pressing important owing to increasing severity of weather thought to arise from global climate change. When rice is completely submerged, different types adopt either a quiescence survival strategy (i.e., minimal shoot elongation) or an escape strategy (i.e., enhanced shoot elongation). Each strategy can prolong survival depending on the circumstances. While submergence responses have been studied in rice typical of lowland and flood-prone areas, few studies have explored the physiological and molecular properties of upland rice under submergence. Here, we use seedlings of the upland rice ‘Tung Lu 3’ (‘TL3’) to analyze physiological and molecular responses to submergence. We compare them with those of ‘FR13A’, a lowland rice that tolerates submergence by adopting the quiescence strategy.

Results

Plant height and distance between leaf sheaths, increased rapidly in ‘TL3’ under submergence. Although this indicated a strong escape strategy the seedlings remained totally underwater for the duration of the experiments. In contrast, ‘FR13A’ elongated much less. Consequently, after 4 days complete submergence followed by drainage, ‘TL3’ lodged much more severely than ‘FR13A’. After 10 d complete submergence, 55% of ‘TL3’ seedlings survived compared to 100% in ‘FR13A’. Chlorophyll a, b and total chlorophyll concentrations of the 2^nd oldest leaves of ‘TL3’ were also significantly above those of ‘FR13A’ (but were lower than ‘FR13A’ in the 3^rd oldest leaves) and less hydrogen peroxide accumulated in ‘TL3’. Peroxidase activity in submerged ‘TL3’ was also greater than in ‘FR13A’ 1 day after submergence. Quantitative RT–PCR showed increased expression of sucrose synthase 1 and alcohol dehydrogenases 1 after 2 days complete submergence with significantly higher levels in ‘TL3’ compared to ‘FR13A’. Expression was also higher in ‘TL3’ under non-submerged conditions.

Conclusions

The upland rice line ‘TL3’ gave a stronger elongation response than ‘FR13A’ to complete submergence. This escape strategy is widely considered to prejudice survival when the plant remains totally submerged. However, contrary to expectations, ‘TL3’ survival rates were substantial although below those for ‘FR13A’ while physiological, biochemical and molecular parameters linked to adaptation differed in detail but appeared to be broadly comparable. These findings highlight that submergence tolerance is determine not only by the adoption of quiescence or escape strategies but maybe by metabolic and physiological properties unrelated to the underwater elongation rate.

     

Evaluation of rice accessions for resistance to the whitebacked planthopper Sogatella furcifera (Horváth) (Homoptera: Delphacidae)

Rice, Oryza sativa L., and wild rice accessions from the world collection were evaluated for resistance to the whitebacked planthopper, Sogatella furcifera (Horváth). Of 48554 O. sativa accessions from 96 countries, 401 (0·8%) were selected for resistance and 351 (88%) of these were from Nepal, India, and Pakistan where S. furcifera is a serious pest. However, some resistant accessions originated from regions beyond the distribution of S. furcifera. Many of the wild rice accessions, consisting of 28 species primarily from the O. minuta Presl., O. nivara Sharma et Shastry and O. officinalis Wall groups, were resistant. Although no S. furcifera-resistant commercial cultivars have been released, advanced breeding lines with resistance to S. furcifera and other major insect pests have been developed.     

Insecticide-induced changes in the levels of resistance of rice cultivars to the whitebacked planthopper Sogatella furcifera (Horváth) (Homoptera: Delphacidae)

IR2035-117-3 (highly resistant), ARC 10239 (resistant), and TN1 (susceptible) rice plants received one application at 40 days after transplanting (DT) or three spray applications (20, 30, and 40DT) of monocrotophos, diazinon or deltamethrin. When these plants were exposed to S. furcifera adults, either 24 hours after the single application, or 15 days after the third of the spray applications, the deltamethrin-treated were most preferred. The percentage of S. furcifera that alighted on the three varieties decreased correspondingly with an increase in the level of varietal resistance. Differences in S. furcifera population growth, nymphal survival, nymphal duration, growth index and feeding rate between IR2035-117-3 and TN1 were significant. Foliar application of deltamethrin caused a significant increase in population growth on IR2035-117-3, ARC 10239, and TN1 and an increase in the nymphal survival and growth index on TN1.     

Monitoring of Insecticide Resistance and Genetic Analysis of Triazophos Resistance in Chilo suppressalis (Lepidoptera: Pyralidae)

During 2001 and 2002, insecticide resistance in the fourth instar larvae of striped stem borer (Chilo suppressalis), which were collected from Zhejiang, Jiangsu, Anhui and Jiangxi provinces in China, was monitored using topical application method. Low level of resistance to fipronil (6.5-fold) was detected for the first time in RA (Rui’an) population from southeast Zhejiang, but the other six populations tested remained susceptible to this recently introduced insecticide. No resistance to abamectin had been found after examining six populations from Zhejiang, Jiangsu and Anhui provinces. Resistance to triazophos was monitored in ten populations from the four Provinces, and very high level resistance(163.1-fold) was found in RA population, moderate (18.2-fold) in WZ (Wenzhou, Zhejiang Province) population, and low (6.7- to 9.7-fold) in populations of CS (Changshu), XS (Xishan) and JT (Jintan) from south Jiangsu, whereas the other five populations were susceptible. All the nine populations monitored were resistant to monosultap with varying degree, i.e. high level (113.7- and 57.6-fold, respectively) of resistance in RA and YF (Yifeng, Jiangxi Province) populations, moderate (11.0- to 29.7-fold) in WZ, CS, JT and TH (Taihu, Anhui Province) populations, low (6.7- and 7.5-fold, respectively) in XY (Xinyang, Jiangsu Province) and XS populations, and the lowest (3.7-fold) in GY (Guanyun, Jiangsu Province) population. Inheritance of resistance in triazophos selected strain Rts was studied through reciprocal cross and backcross experiments. The preliminary results indicated that inheritance of triazophos resistance in Rts strain was incompletely dominant, with degrees of dominance being 0.46 and 0.68 for reciprocal crosses, and that the resistance was controlled by a major gene, though minor modifying gene(s) might be involved.     

Assessment of the effects of crop injury by blackcurrant leaf midge,Dasineura tetensi (Rübsaamen) (Cecidomyiidae) on yield and growth in commercial blackcurrant plantations

Sex pheromone trap catches, galling damage, yield and growth were recorded over up to three successive seasons (2010–2012) in large replicated plots treated versus untreated with synthetic pyrethroid (SP) insecticides for blackcurrant leaf midge Dasineura tetensi control in eight established commercial blackcurrant plantations in southern England. The aim was to determine whether or not the current practice of spraying insecticides against the pest in commercial fruiting plantations is justified. In two separate small plot replicated experiments (in 2010 and 2011, respectively) in plantations which had been cut down in the previous winter, galling damage and shoot growth were recorded in the vigorous regrowth in plots treated versus untreated with SP insecticides against 1st, 2nd or both D. tetensi generations. Cutting down bushes to ground level in this way is a common way of regenerating plantations.In the experiments in the established fruiting plantations, applying sprays of insecticides led to substantial reductions in numbers of adult D. tetensi caught in sex pheromone traps (by 72% on average) and reductions in galling damage (by 75% on average) but did not result in increases in yield or statistically significant increases in shoot growth. Multiple possible mechanisms of yield compensation are discussed. In the experiments in the cut-down bushes where the galling was intense, the D. tetensi damage resulted in severe (59%) stunting and multiple branching of the regrowth which was weak and thin. Sprays against the 2nd generation only partially reduced stunting (to 24%).The results of this work call into question the current commercial practice of controlling this pest in established commercial plantations with sprays of insecticides: as significant increases in yield or growth did not result in these experiments, the effects of the sprays was largely cosmetic. Further, broad spectrum synthetic pyrethroid insecticides are likely to have persistent adverse effects on the natural enemies of D. tetensi. However, the work showed that control in re-growing cut-down plantations, and by analogy in young establishing plantations, is vital, as well as the value of the D. tetensi sex pheromone traps for timing sprays of insecticides.     

Identification and Characterization of Two “Sensory Neuron Membrane Proteins” (SNMPs) of the Desert Locust,Schistocerca gregaria (Orthoptera: Acrididae)

Pheromone-responsive neurons of insects not only require specific receptors but in addition several auxiliary components, including the “sensory neuron membrane protein,” SNMP. Accordingly, SNMP is considered as a marker for neurons responding to pheromones. For the desert locust Schistocerca gregaria, it is known that the behavior, including aggregation behavior and courtship inhibition, is largely controlled by pheromones. However, little is known about pheromones, their receptors, and the pheromone-responsive cells in locusts. In this study, we have identified two SNMP subtypes, SNMP1 and SNMP2, and compared their phylogenetic relationship and primary structure motifs with SNMPs from other species. Both SNMPs were found in chemosensory tissues, especially the antennae. Employing double in situ hybridization, we identified and localized the SNMP-expressing cells in the antennae. Cells expressing SNMP1 were localized to sensilla trichodea but also to sensilla basiconica, which in locust respond to pheromones. One or a few cells express SNMP1 within the multineuron clusters from sensilla basiconica, whereas the SNMP2 subtype was expressed in cells surrounding the neuron clusters, possibly supporting cells. Based on the finding that SNMP1 is expressed in distinct neurons under chemosensory sensilla, it is conceivable that these cells may represent pheromone-responsive neurons of the desert locust.     

Effects of Cultivar and Environment on β-(1,3)-(1,4)-D-glucan Content and Acid Extract Viscosity of Spanish Barleys

The acid extract viscosities and β-glucan contents of ten two- and six-rowed barley cultivars grown at seven locations in three consecutive years in Spain were studied in the present work. The viscosities varied from 2·4 to 24·8 centistokes (cSt) and the mean value was 6·4 cSt. The average β-glucan content of barleys determined by HPLC was 3·5% with a range of 1·9–5·5%. Significant differences were found in both β-glucan content and acid extract viscosity between different cultivars, locations and years. The β-glucan contents and viscosities of winter cultivars were higher than those of spring. Cvs. Barbarrosa and Hatif de Grignon were the genotypes with the highest values for both parameters, while cv. Beka had the lowest viscosity and β-glucan content. Environmental factors influenced both parameters. The acid extract viscosities of barleys were correlated negatively with the amount of precipitation (r=−0·754;P<0·05). Barleys grown in wet and rainy areas (Girona and La Coruña) had lower viscosity values.     

【Short Report】Influence of the Improved System of Rice Intensification (SRI) on Rice Yield,Yield Components and Tillering Characteristics under Different Rice Establishment Methods

Abstract

The impacts of the system of rice intensification (SRI) and conventional management (CM) on grain yield, yield components and tillering capacity were examined under 4 rice establishment methods transplanting (TP), seedling casting (SC), mechanical transplanting (MT) and direct seeding (DS). SRI produced significantly higher grain yield than CM under TP and MT but not under DS or SC. DS and SC produced much higher seedling quality than TP or MT, suggesting that robust seedlings with vigorous roots weaken the positive effect of SRI on rice yield. SRI produced a higher tillering rate than CM, but did not affect ear-bearing tiller rate significantly. Moreover, the net photosynthetic rate of the recent fully expanded leaf at mid-tillering stage was significantly higher in SRI than in CM under MT and TP. The obtained results also indicated that SRI increased biomass accumulation before heading and improved utilization of photosynthates in the grain-filling stage.     

Distribution and Abundance of Necrophagous Flies (Diptera: Calliphoridae and Sarcophagidae) in Maranh?o,Northeastern Brazil

This study aimed at surveying the local calliphorid and sarcophagid species in Maranhão State (Brazil) to determine their distribution and abundance, as well as the distribution of exotic Chrysomya species. In total, 18,128 calliphorid specimens were collected, distributed in 7 genera and 14 species. The species Hemilucilia semidiaphana (Rondani, 1850) and Paralucilia paraensis (Mello, 1969) were new state records. Chrysomya albiceps (Wiedemann, 1819) and Cochliomyia macellaria (F., 1775) were the most abundant species, and the exotic species of Chrysomya together contributed more than 50% of total blow fly abundance. The abundance distribution of the calliphorid community conformed to a log series model, characterized by a steep curve that reflects an assemblage with a high degree of dominance. For the Sarcophagidae, a total of 14,810 specimens were collected and distributed in 15 genera, 11 subgenera, and 52 species. Tricharaea (Sarcophagula) occidua (F., 1794) and Peckia (Sarcodexia) lambens (Wiedemann, 1830) were the most abundant species. The abundance distribution of the species followed a log normal model, with a gentler slope, consistent with a more uniform community. The cumulative species curve for the sarcophagids did not reach the asymptote. Forty-three sarcophagid species were new state records and 22 were new records for the Brazilian northeast, which emphasizes the need for a continued survey in this region.