Microbial inoculant effects on silage and in vitro ruminal fermentation, and microbial biomass estimation for alfalfa, bmr corn, and corn silages

Whole crop third cut alfalfa, brown mid-rib (bmr) corn, and corn were chopped and inoculated with one of four microbial inoculants used. Uninoculated silage was the control treatment. Each crop was ensiled in four mini-silos (1 L glass jars) per treatment. All silos were fermented for 60 days at room temperature (22 °C), and then they were opened and analyzed for fermentation products, fiber constituents and N fractions. A fraction of wet silage was ground with a blender for 30 s. In vitro gas production was measured in 160 ml sealed serum vials at 3, 6, 9, 24, and 48 h using the wet ground silage. At 9 and 48 h, rumen fluid was analyzed for volatile fatty acids (VFA) and microbial biomass yield (MBY). In all the three crops, the four inoculants produced only minor changes in pH and fermentation products during ensiling. Of the variables measured, soluble nonprotein N fractions were the characteristics most often affected by some inoculants. At 9 h incubation, in vitro gas production and VFA did not differ between control and inoculated silages, but MBY did. Among crops, alfalfa and corn silages had higher MBY than did bmr corn silage. Among inoculants, three of the four inoculated silages produced more MBY than did control. At 48 h, alfalfa silage produced higher MBY than did corn or bmr silage, and two of the inoculated silages had more MBY than did the control. There was no inoculant by crop interaction. Results suggest that some silage inoculants are capable of altering rumen fermentation, even in cases where effects on silage fermentation are small, and that this effect may be linked to better preservation of crop protein during ensiling.     

Gluttony and sex in female ixodid ticks: how do they compare to other blood-sucking arthropods?

The central issue dealt with here is the role of copulation in the control of feeding behaviour in ticks and some haematophagous insects. Female ticks of the family Ixodidae normally engorge to approximately 100 x their unfed body weight, and then drop from the host, produce and lay eggs, and die. Virgins, on the other hand, normally do not exceed 5-40% (depending on species) of the normal engorged body weight. But instead of detaching voluntarily at that point most virgins remain fixed to the host for extended periods, waiting for males to find them so they can complete engorgement. Virgin haematophagous insects, and virgin ticks of the family Argasidae display little, if any, reduction in blood meal size compared to mated females, at least not during the first ovarian cycle. During subsequent ovarian cycles, meal size in some virgin insects may be somewhat reduced depending on how many eggs are retained in the reproductive tract, but the reduction is not nearly to the same extent as that observed for virgin ixodid females. The stimulatory effect of copulation on engorgement in the latter is caused by a pair of proteins (voraxin alpha and beta) produced in the testis and transferred to the female with the spermatophore. Here, I propose why it might be adaptive for an ixodid female to remain small until mated. The hypothesis is suggested from the facts that ixodid ticks remain attached to the host for days (rather than minutes), and that virgin ticks, above a certain critical weight, lose all opportunity for producing viable offspring should they be groomed off the host prematurely, or should the host die while ticks are still attached.     

Length–biomass equations to allow rapid assessment of semi-aquatic bug biomass in tropical streams

Length–biomass equations are relatively easy and cost-effective for deriving insect biomass. However, the exact relationship can vary between taxa and geographical regions. Semi-aquatic bugs are abundant and are indicators of freshwater quality, but there are no studies investigating the effect of habitat disturbance on their biomass, although it is useful in assessing ecological processes. We identified the best-fit length–biomass models to predict the biomass of semi-aquatic bugs (Hemiptera, Gerromorpha) collected from streams in Sabah, Malaysia. We used 259 juvenile and adult semi-aquatic bugs to compare a range of plausible length–biomass functions, and to assess whether relationships differed across the following families and body forms: (1) Cylindrostethinae, Gerrinae, and Ptilomerinae, which are subfamilies within Gerridae consisting of small-to-large bugs that have long and slender bodies, (2) Halobatinae, a subfamily within Gerridae, consisting of small-to-medium bugs with wide heads and thoraxes as well as short abdomens, and (3) Veliidae, which are small bugs with stout bodies. Estimation used five fitting functions – linear regression, polynomial regression order 2, 3, and 4, and power regression – on the following groupings: three body forms combined; each body form with life stages (juvenile and adult) combined; and each body form with life stages separated. Power regressions were the best fit in predicting the biomass of semi-aquatic bugs across life stages and body forms, and the predictive power of models was higher when the biomass of different body forms was calculated separately (specifically for Halobatinae and Veliidae). Splitting by life stages did not always result in additional improvement. The equations from this study expand the scope of possible future ecological research on semi-aquatic bugs, particularly in Southeast Asia, by allowing more studies to consider biomass-related questions.     

Spatial distribution and sampling plan of the phytophagous stink bug complex in different soybean production systems

Phytophagous stink bugs are major soybean pests, and knowledge of spatial distribution models of the pest in the crop is fundamental to establishing an appropriate sequential sampling plan, and thus, allowing the correct utilization of control strategies. This work aimed to study the spatial distribution of phytophagous stink bugs in soybean grown in different cropping systems and determine a sequential sampling plan. The experiment was conducted in Maracaju, MS, Brazil, during the agricultural year of 2012/2013. Soybean cultivars BRS 284 and SYN 1163 RR were placed in an experimental area comprising six fields (two soybean cultivars × three cropping systems). Sampling was performed weekly, using a beat cloth per plot and counting the number of stink bugs found, virtually throughout the soybean reproductive period. Concerning the statistical analyses, we used the dispersion indexes (variance‐to‐mean ratio, Morisita's index, exponent k of the negative binomial and Green's coefficient) and probabilistic methods of frequency adjustment (negative binomial and Poisson). Adult and nymph phytophagous stink bugs showed aggregate disposition in the field regardless of the cropping system, and their numbers were adjusted to the negative binomial probability distribution. There was no difference in the behaviour of adult and nymphs considering the tested cultivars. We elaborated a practical sequential sampling plan for phytophagous stink bug complexes, considering crops intended for the production of grains and seeds.     

三种棉盲蝽对不同棉花品种的选择偏好性及种群动态

【目的】明确我国华北地区棉盲蝽优势种对不同种棉花品种的选择偏好性,以及这几种盲蝽的种群动态及发生规律。【方法】2013和2014年通过小区随机排列田间系统调查的方法,比较分析了中黑盲蝽Adelphocoris suturalis(Jakovlev)、三点盲蝽Adelphocoris fasciaticollis(Reuter)和绿盲蝽Apolygus lucorum(Meyer-Dür)对12个棉花品种的选择偏好性,种群动态及与温度的关系。【结果】3种盲蝽均对石亚系1号表现出明显偏好性,对N73Deltapine FO表现出明显的不偏好性。棉盲蝽在每年7月初开始危害,7月下旬及8月上旬盲蝽种群密度达到峰值,9月上旬种群密度逐渐降低,9月中下旬盲蝽迁出棉田。在本实验调查的温度范围内(17~35℃),盲蝽种群密度随着温度升高而增大。【结论】棉盲蝽对不同品种有明显选择偏好性,盲蝽种群大的地区推荐种植盲蝽厌食品种。     

Comparison of distance sampling estimates to a known population size of Ant-eating Chats Myrmecocichla formicivora

Line-transect sampling was used to obtain abundance estimates of an Ant-eating Chat Myrmecocichla formicivora population to compare these with the true size of the population. The population size was determined by a long-term banding study, and abundance estimates were obtained by surveying line transects. The sampling effort was quadrupled to determine potential improvements in accuracy and precision. Abundance estimates of the single surveys differed up to 19.8% from the true number of birds and showed relatively high coefficients of variation. Estimates of the cumulative analyses only differed up to 5.8% while coefficients of variation improved considerably, and provided thus reliable population estimates compared with the true number of chats.     

Effect of predators and host phenology on the maternal and reproductive behaviors ofGargaphia lace bugs (Hemiptera: Tingidae)

Lace bugs of the genus Gargaphia specialize on taxonomically and ecologically diverse host plants. To examine the impact of predation pressure and host phenology on Gargaphia subsocial and reproductive behavior, we compared G. tiliae, a woodland species restricted to riparian trees in the genus Tilia, and G. solani, a specialist on Solanum in early successional habitats. Both lace bug species exhibit maternal care of eggs and nymphs. Predator densities associated with Solanum were higher than those associated with Tilia and were correlated with higher levels of maternal aggression exhibited by G. solani. In both habitats, artificial exclusion of predators significantly increased nymphal survivorship over maternally guarded broods. Both species reduced the costs associated with maternal care by ovipositing into the egg masses of conspecifics. Gargaphia solani and G. tiliae differed most strikingly in voltinism and thus the potential for iteroparity. Leaf age determined the reproductive future of G. tiliae nymphs independent of photoperiod or temperature. Feeding on plants with young foliage was sufficient to trigger oviposition. Constraints imposed by host plants on life-history patterns and maternal options are discussed.     

灰绒泡菌生活史及其子实体发育过程的显微观察

为明确灰绒泡菌Physarum cinereum的个体发育特征,本研究在实验室条件下完成了该菌的生活史,并对其子实体发育过程进行显微观察。灰绒泡菌P. cinereum孢子萌发方式为裂式,显型原质团水白色;子实体形态建成可分为孢囊形成期和孢囊成熟期,孢囊成熟期幼孢囊颜色随着孢子的形成呈现白色-红棕色-黑褐色逐渐加深的变化;子实体在发育过程中孢丝形成后原生质割裂形成孢子。     

Beech versus spruce deadwood as forest microhabitat: does it make any difference to bryophytes?

The presence data of 153 bryophyte species, recorded on beech (BDW) and spruce (SDW) deadwood in the managed forests within a montane watershed, were analysed by controlling for different plot size, substrate pH and elevation. Only three pleurocarpous species, which were probably remnant epiphytes from live wood, showed relative specificity for BDW, but none to SDW. The few species displaying preference for BDW or SDW were generally true epixylic, mosses and hepatics, respectively. The chances of occurrence of epiphytic (early successional) and epixylic (mid-late successional) taxa on either deadwood species increased and respectively, decreased with the substrate pH. There was no consistent relationship between bryophyte preference to BDW/SDW and elevation. Neither total nor threatened species richness was related to deadwood species identity. However, at 100 cm² resolution and within certain extension range, the cumulative number of bryophyte species was significantly higher on BDW than on SDW, despite no significant difference in species pool size. Threatened species richness increased monotonically towards lower elevations, suggesting that valley bottoms might act as refugia with high air humidity. The number of threatened species and in particular, the presence of Lophozia ascendens, were good predictors of total bryophyte richness regardless of deadwood species identity.     

Multiple mating in the traumatically inseminating Warehouse pirate bug, Xylocoris flavipes: effects on fecundity and longevity

Optimal mating frequencies differ between sexes as a consequence of the sexual differentiation of reproductive costs per mating, where mating is normally more costly to females than males. In mating systems where sexual reproduction is costly to females, sexual conflict may cause both direct (i.e. by reducing female fecundity or causing mortality) and indirect (i.e. increased risk of mortality, reduced offspring viability) reductions in lifetime reproductive success of females, which have individual and population consequences. We investigated the direct and indirect costs of multiple mating in a traumatically inseminating (TI) predatory Warehouse pirate bug, Xylocoris flavipes (Reuter) (Hemiptera: Anthocoridae), where the male penetrates the female's abdomen during copulation. This study aimed to quantify the effects of TI on female fecundity, egg viability, the lifetime fecundity schedule, longevity and prey consumption in this cosmopolitan biocontrol agent. We found no difference in the total reproductive output between mating treatments in terms of total eggs laid or offspring viability, but there were significant differences found in daily fecundity schedules and adult longevity. In terms of lifetime reproduction, female Warehouse pirate bugs appear to be adapted to compensate for the costs of TI mating to their longevity.