Disentangling Diet- and Medium-Associated Microbes in Shaping Daphnia Gut Microbiome

Host genotype and environment are considered crucial factors in shaping Daphnia gut microbiome composition. Among the environmental factors, diet is an important factor that regulates Daphnia microbiome. Most of the studies only focused on the use of axenic diet and non-sterile medium to investigate their effects on Daphnia microbiome. However, in natural environment, Daphnia diets such as phytoplankton are associated with microbes and could affect Daphnia microbiome composition and fitness, but remain relatively poorly understood compared to that of axenic diet. To test this, we cultured two Daphnia magna genotypes (genotype-1 and genotype-2) in sterile medium and fed with axenic diet. To check the effects of algal diet-associated microbes versus free water-related microbes, Daphnia were respectively inoculated with three different inoculums: medium microbial inoculum, diet-associated microbial inoculum, and medium and diet-mixed microbial inoculum. Daphnia were cultured for 3 weeks and their gut microbiome and life history traits were recorded. Results showed that Daphnia inoculated with medium microbial inoculum were dominated by Comamonadaceae in both genotypes. In Daphnia inoculated with mixed inoculum, genotype-1 microbiome was highly changed, whereas genotype-2 microbiome was slightly altered. Daphnia inoculated with diet microbial inoculum has almost the same microbiome in both genotypes. The total number of neonates and body size were significantly reduced in Daphnia inoculated with diet microbial inoculum regardless of genotype compared to all other treatments. Overall, this study shows that the microbiome of Daphnia is flexible and varies with genotype and diet- and medium-associated microbes, but not every bacteria is beneficial to Daphnia, and only symbionts can increase Daphnia performance.

Comparison of some zootechnical performances of local and Red Maradi goats reared under smallholder production systems in the Sudanian zone of Benin

•

Zootechnical performances of indigenous and Maradi goats reared in Sudanian zone of Benin were compared.

•

Demographic parameters determine the productivity of goat flocks.

•

Red Maradi goat has a good milk potential compared to local goat breeds.

•

Enhancement of goat herds’ productivity is possible through improved breeding practices.

The aim of this research was to compare the zootechnical performances of indigenous and Maradi goats reared under village conditions in the Sudanian zone of Benin. A questionnaire survey was carried out between August and October 2019, using the 12MO, a retrospective method for estimating demographic parameters in tropical ruminant livestock population and the progeny history method. Information related to farmers’ socioeconomic characteristics, goat herd management practices and demographic parameters, and milk productivity from 198 does including 66 West African Dwarf (WADG), 68 Red Maradi (RMG) and 64 West African long-legged (WLLG) goats were collected in 80 smallholder farms. Pearson Chi-square and Kruskal-Wallis W tests were performed respectively on the categorical and continuous variables. The average herd size was about 16.7 ± 9.0; 5.8 ± 3.1 and 15.4 ± 7.4 heads respectively for WADG, RMG and WLLG. Bucks were absent in several herds where kids (47.9 ± 12.8%) and does (46.6 ± 12.8%) predominated. Prolificacy rates at first and second parturition varied significantly (P ≤ 0.05) among goat types and were respectively 165.2 ± 59.5% and 195.1 ± 66.9% for WADG; 160.3 ± 55.0% and 196.0 ± 53.9% for RMG; 134.4 ± 54.1% and 154.6 ± 51.0% for WLLG. Parturition rates were higher (P ≤ 0.05) in WADG (159.1 ± 49.5%) than in RMG (138.2 ± 49.0%) and WLLG (132.8 ± 47.3%). Likewise, productive rates were higher (P ≤ 0.05) in WADG (277.3 ± 142.3%) than in RMG and WLLG (204.4 ± 125.1% and 168.8 ± 102.2% respectively). Milking was only performed on RMG and the amount of milk collected per milking ranged between 0.6 and 1 liter per doe. Enhancing goat herds’ productivity could be achieved through improved general herd management practices.

Reproductive performance and milk production of Central Highland and Boer x Central Highland goats

This study was conducted to evaluate the reproductive performance and milk production potential of Central Highland and Boer x Central Highland goats under semi-intensive management. Data were collected from 2009 till 2018 in the Sirinka goat breeding station. A general linear model procedure of the Statistical Analysis System (SAS) was used to analyze the data. The overall least-squares mean litter size at birth (LSB), litter size at weaning (LSW), total litter weight at birth, total litter weight at weaning and gestation length (GL) were 1.6 ± 0.02 kids, 1.4 ± 0.02 kids, 3.9 ± 0.05 kg, 13.6 ± 0.35 kg and 148.0 ± 0.33 days, respectively. The LSB, LSW and GL did not differ between Central Highland and their F1 and F2 crossbred dams. However, F2 dams produce the lightest kid at birth and weaning. Besides, birth type, season, year and parity were important sources of variation for most of the reproductive traits. The least-squares mean for daily milk yield (DMY), lactation milk yield (LMY) and lactation length (LL) were 0.34 ± 0.02 kg, 39.16 ± 3.00 kg and 104.2 ± 4.45 days, respectively. The DMY and LMY of Boer x Central Highland goats were higher than pure Central Highland goats by 46.4% and 27.2%, respectively. However, the LL for both genotypes was found to be similar (P > 0.05). Dams kidding during the short rainy season produce more milk than kidding during dry and main rainy seasons. Boer x Central Highland goats produce more milk than pure Central Highland goats. However, using Boer crossbred dams did not reveal any advantage over the base Central Highland dams in terms of reproductive performance. Therefore, using Central Highland goat as a dam line, improving the management and integration of crossbreeding with selection could be an ideal option to improve the overall productivity of goats.

Fitness cost, realized heritability and stability of resistance to spiromesifen in house fly, Musca domestica L. (Diptera: Muscidae)

The house fly, Musca domestica L. (Diptera: Muscidae), is an insect pest of public health and veterinary importance. Spiromesifen is a new chemistry insecticide widely used for the management of sucking insect pests of vegetables and crops. In the present study, assessment of resistance risk and fitness costs associated with spiromesifen resistance in M. domestica was studied. Moreover, stability of resistance to spiromesifen and other tested insecticides (fipronil, spinosad, and bifenthrin) was evaluated in the spiromesifen-selected-strain (SPIRO-SEL-POP). After 7-generations of selection with spiromesifen, SPIRO-SEL-POP developed 108.76-fold resistance compared with the unselected strain (UNSEL-POP). The estimated value of realized heritability was 0.59 for spiromesifen resistance. Due to withdrawal of spiromesifen selection for five generations (F₆-F₁₀) on SPIRO-SEL-POP, a decline in LC₅₀ values against spiromesifen, spinosad and bifenthrin was 0.16, 0.14 and 0.13-folds, respectively. In biological trait experiments, larval weight of Cross₁ (SPIRO-SEL-POP♀ × UNSEL-POP♂) and SPIRO-SEL-POP was significantly lower than that of Cross₂ (SPIRO-SEL-POP♂ × UNSEL-POP♀) and UNSEL-POP. Pupal weight of SPIRO-SEL-POP was higher when compared with Cross₁ while it was similar to that of Cross₂ and UNSEL-POP. Adult emergence rate of UNSEL-POP was higher than Cross₁, but similar to the Cross₂ and SPIRO-SEL-POP. The SPIRO-SEL-POP and Cross₁ showed the lowest relative fitness when compared with USEL-POP and Cross₂. Intrinsic rate of natural increase of SPIRO-SEL-POP was much lower than that of UNSEL-POP and Cross₂ followed by Cross₁. The SPIRO-SEL-POP exhibited lower biotic potential when compared with UNSEL-POP and Cross₂ but similar to Cross₁. Fecundity and hatching rates were lower in SPIRO-SEL-POP compared to UNSEL-POP. It could be concluded that spiromesifen resistance in M. domestica comes with a cost and is instable. Therefore, spiromesifen rotation with other insecticides and withdraw of its usage for some period could help to sustain its efficacy by delaying the development of resistance.

Predatory functional response and fitness parameters of Orius strigicollis Poppius when fed Bemisia tabaci and Trialeurodes vaporariorum as determined by age-stage, two-sex life table

Background

The polyphagous predatory bug O. strigicollis is an active predator used to control thrips and aphids. The whitefly species Bemisia tabaci and Trialeurodes vaporariorum are voracious pests of different economic agricultural crops and vegetables.

Method

In this study, the Holling disc equation and the age-stage, two-sex life table technique were used to investigate the functional response and biological traits of third instar nymphs and adult female O. strigicollis when presented third instar nymphs of both whitefly species as prey.

Results

The results showed a type II functional response for each life stage of O. strigicollis when fed each whitefly species. The calculated prey handling time for different O. strigicollis life stages were shorter when fed T. vaporariorum than when fed B. tabaci nymphs. In contrast, the nymphal development of O. strigicollis was significantly shorter when fed B. tabaci than T. vaporariorum nymphs. Additionally, the total pre-oviposition period of adult females was statistically shorter when fed B. tabaci nymphs than T. vaporariorum nymphs. Furthermore, the survival rates and total fecundity of O. strigicollis were higher when fed B. tabaci than T. vaporariorum. There were no significant differences in any population parameters of O. strigicollis when fed either whitefly species. These results show that O. strigicollis could survive and maintain its populations on both species of whitefly and could therefore serve as a biological control agent in integrated pest management (IPM).

Survival analysis and reproductive performance of Dorper x Tumele sheep

Productivity and profitability of sheep farming are highly influenced by lamb survival and ewe reproductive performance. Thus, this study was conducted to evaluate the survival and reproductive performance of crossbred sheep. Data collected from 2009 to 2018 from Sirinka sheep breeding stations were utilized for this study. Survival analysis was conducted by using Survival Kit 6.12 software with the Weibull model and the general linear model of SAS 9.0 was used to analyze reproductive traits. The overall mean survival rate of Dorper x Tumele crossbred lambs at 3, 6 and 12 months of age were 86.0, 76.6, and 67.9%, respectively. About 46.8% of mortality from the total death was observed during the first 120 days of life. Gastrointestinal parasites, pneumonia and septicemia were the major causes of lamb mortality. Birth weight, birth type, sex and year of lambing were the most important risk factors for survival of crossbred lambs. The overall least-squares means for litter size at birth, litter size at weaning, total litter weight at birth and total litter weight at weaning were 1.10 lambs, 0.94 lambs, 3.28 kg and 15.5 kg, respectively. Birth type, sex and year of lambing were the most determinants of ewe productive traits. Tumele and their crossbred sheep had good mothering ability necessary to successfully raise lambs to weaning. The current crossbreeding program which aims to improving growth performance had a positive influence on the survival rate of lambs. Improvement of environmental in the flock, special care for small lambs and indirect selection based on birth weight would lead to further survival improvement.

Acute and (sub)chronic toxicity of the neonicotinoid imidacloprid on Chironomus riparius

Impacts of neonicotinoids on non-target insects, including aquatic species, may significantly influence ecosystem structure and functioning. The present study investigated the sensitivity of Chironomus riparius to imidacloprid exposures during 24-h, 10- and 28-days by assessing larval survival, growth, emergence and oxidative stress-related parameters. C. riparius exhibited high sensitivity compared to other model aquatic species with acute 24-h LC₅₀ being 31.5 μg/L and 10-days LOEC (growth) 0.625 μg/L. A 28-days partial life cycle test demonstrated imidacloprid effects on the emergence of C. riparius. Exposure to sublethal concentrations during 10-days caused an imbalance in the reduced and oxidized glutathione (GSH and GSSG), and slightly induced lipid peroxidation (increased malondialdehyde, MDA). Our results indicate that oxidative stress may be a relevant mechanism in the neonicotinoid toxicity, reflected in the insect development and life cycle parameters.

Influence of dietary cadmium exposure on fitness traits and its accumulation (with an overview on trace elements) in Lymantria dispar larvae

Bioaccumulation and excretion of heavy metals in insects is only partially clarified. We have investigated cadmium accumulation in the feces, head and integument of Lymantria dispar (Lepidoptera: Lymantriidae) larvae exposed to chronic dietary intake of cadmium. The aim of the experiment was to establish modalities of metal accumulation, primarily cadmium, as well as changes in fitness traits in two insect populations receiving 50 or 100μgCd/g dry food. The egg-masses originated from two localities: a protected nature reserve (unpolluted population) and an area near a busy highway (polluted population) in Serbia. At both added dietary levels cadmium concentration was highest in feces. Small alterations in metal concentrations after both cadmium treatments were detected in the integument. It was established that irrespective of population origin, the modality of decline of larval mass and relative growth rate (RGR) was similar. Concentrations of Cu and Zn in the integument were approximately the same regardless of dietary cadmium intake. However, cadmium accumulation in the examined tissues, as well as variability of fitness traits depended on population origin and cadmium concentration. In larvae from both populations not given contaminated food the head was the organ with the greatest accumulation of trace elements. Our results reveal how invasive phytophagous insects cope with high metal concentrations in their food by body mass (RGR) reduction and energy allocation towards processes that enable accumulation of cadmium and other trace elements in different tissues.

Chronic exposure to dim artificial light at night decreases fecundity and adult survival in Drosophila melanogaster

The presence of artificial light at night is expanding in geographical range and increasing in intensity to such an extent that species living in urban environments may never experience natural darkness. The negative ecological consequences of artificial night lighting have been identified in several key life history traits across multiple taxa (albeit with a strong vertebrate focus); comparable data for invertebrates is lacking. In this study, we explored the effect of chronic exposure to different night-time lighting intensities on growth, reproduction and survival in Drosophila melanogaster. We reared three generations of flies under identical daytime light conditions (2600lx) and one of four ecologically relevant ALAN treatments (0, 1, 10 or 100lx), then explored variation in oviposition, number of eggs produced, juvenile growth and survival and adult survival. We found that, in the presence of light at night (1, 10 and 100lx treatments), the probability of a female commencing oviposition and the number of eggs laid was significantly reduced. This did not translate into differences at the juvenile phase: juvenile development times and the probability of eclosing as an adult were comparable across all treatments. However, we demonstrate for the first time a direct link between chronic exposure to light at night (greater than 1lx) and adult survival. Our data highlight that ALAN has the capacity to cause dramatic shifts in multiple life history traits at both the individual and population level. Such shifts are likely to be species-specific, however a more in depth understanding of the broad-scale impact of ALAN and the relevant mechanisms driving biological change is urgently required as we move into an increasing brightly lit future.