Activity of Chloroformic Extract from Salvia connivens (Lamiales: Lamiaceae) and Its Principal Compounds against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae) is one of the most damaging pests in maize crops. In order to manage it, synthetic insecticides such as diamides, neonicotinoids, and pyrethroids are used, but they present a risk for humans and the environment. Investigations of safer alternatives include the use of natural extracts. Thus, this research evaluated the effects of chloroform extract (CHCl3Sc) (5000, 4000, 2000, 1000, and 500 ppm) on aerial parts of Salvia connivens and of nonanal and pyrocatechol (1000, 600, 400, and 80 ppm) on S. frugiperda mortality, duration of the larva and pupae phases, and pupae weight after 24 h. The second instars of S. frugiperda larvae were fed an artificial diet incorporating the extract and compounds. The CHCl3Sc had insecticidal activity against S. frugiperda, showing an LC50 of 1504 ppm. Insectistatic activity began at 1000 ppm, increasing pupal and larval duration in 7.6 and 1.4 days, respectively. Pyrocatechol and nonanal were found in this extract. The first did not have any significant difference in larval or pupal mortalities. On the other hand, insectistatic activity was shown at 500 ppm, increasing the larval duration by 1.7 days compared with the control. In the case of nonanal, the insecticide activity was LC50 of 200 ppm, and insectistatic activity started at 80 ppm, increasing larval duration by 3.2 days compared with the control and reducing pupal weight by 3.4%. The results show that chloroformic extract had insecticidal and insectistatic activities against S. frugiperda; nonanal was an aldehyde compound present in this extract, which confers insecticidal and insectistatic activities against this pest.

North Equatorial Current and Kuroshio Velocity Variations Affect Body Length and Distribution of the Japanese eel Anguilla japonica in Taiwan and Japan

The larval stage of Japanese eel travels a substantial distance over a long duration through the North Equatorial Current (NEC) and the Kuroshio, and the spawning behavior of mature eels leads to monthly arrival waves in eastern Taiwan between November and February. The total length (TL) of the glass eel relates to its larval duration and age; therefore, the TL can indicate the larval duration. The monthly mean TLs of eels along eastern Taiwan from 2010–2021 were used to estimate the batch age, and the recruitment patterns and relative abundances were compared. The TLs of glass eels followed a normal distribution, and the estimated ages were highly correlated with their mean TLs. Early recruit TLs were significantly greater than those of late recruits. The mean tracer drift time was longer in early recruitment months (November–December) than in later dates (February–March). The recruitment lag was approximately 1–1.5 months, with relative recruitment higher in the early recruitment months than in later months. Cohorts followed the main streams of the NEC and Kuroshio, and the monthly velocity changes of these currents could affect the TLs as well as the distribution patterns of Japanese glass eels in Taiwan and Japan.

Validating a biophysical dispersal model with the early life-history traits of common sole (Solea solea L.)

Larval dispersal and juvenile survival are crucial in determining variation in recruitment, stock size and adult distribution of commercially important fish. This study investigates the dispersal of early-life stages of common sole (Solea solea L.) in the southern North Sea, both empirically and through modeling. Age at different life-history events of juvenile flatfish sampled along the coasts of Belgium, the Netherlands and the United Kingdom in 2013, 2014 and 2016, was determined through the counting of daily growth rings in the otoliths. Juveniles captured between August and October were estimated to be on average 140 days old with an average pelagic larval duration of 34 days. The hatching period was estimated between early April and mid-May followed by arrival and settlement in the nurseries between May and mid-June. Growth rates were higher off the Belgian coast than in the other nursery areas, especially in 2013, possibly due to a post-settlement differentiation. Empirical pelagic larval duration and settlement distributions were compared with the Larvae&Co larval dispersal model, which combines local hydrodynamics in the North Sea with sole larval behavior. Yearly predicted and observed settlement matched partially, but the model estimated a longer pelagic phase. The observations fitted even better with the modelled average (1995–2015) distribution curves. Aberrant results for the small juvenile sole sampled along the UK coast in March 2016, led to the hypothesis of a winter disruption in the deposition of daily growth rings, potentially related to starvation and lower food availability. The similarities between measured and modelled distribution curves cross-validated both types of estimations and accredited daily ageing of juveniles as a useful method to calibrate biophysical models and to understand early-life history of fish, both important tools in support of efficient fisheries management strategies.

Seasonal variation in larval growth of Eri silkworm (Samia ricini Boisduval) reared on two Ailanthus species

Present study was undertaken to evaluate the impact of different seasons in larval growth of eri silkworm (Samia ricini Boisduval) reared on Ailanthus species viz., borpat (Ailanthus grandis) and borkesseru (Ailanthus excelsa). The study revealed that the larval growth parameters of eri silkworm was found better in terms of larval duration, full grown larval weight and matured larval weight on the borpat leaves as compared to the borkesseru leaves. Considering the seasons, the full grown larval weight and matured larval weight were observed significantly higher during the autumn season but the shortest larval duration was observed during the late summer season.

Amphidromous but endemic: Population connectivity of Rhinogobius gigas (Teleostei: Gobioidei)

Rhinogobius gigas is an amphidromous fish endemic to eastern Taiwan. Fishes with the diadromous behavior are expected to have a broader distribution range and higher genetic homogeneity despite that some amphidromous fishes with limited distribution are observed and R. gigas is an additional exception with a limited distribution range. Rhinogobius gigas has been documented to be retained inshore near the river plume with a short pelagic larval duration of 30–40 days, which may account for the endemism of this species. The short marine larval stage of R. gigas may imply a population genetic structure and the aim of the present study is to test whether the population genetic structure is present in R. gigas. To test the population genetic structure, fragments of mitochondrial displacement loop and cytochrome c oxidase subunit I were sequenced to provide molecular inference for genetic structure among populations. Sixty-nine haplotypes were identified among 191 R. gigas from 10 populations of eastern Taiwan and the mean haplotype and nucleotide diversities for all samples were 0.956 and 0.0024, respectively, implying a bottleneck followed by a recent population expansion further supported by Fu’s Fs (-26.6; p < 0.001) and Tajima’s D (-1.5; p = 0.037) values. The phylogenetic analysis revealed lack of genetic structure and the bush-like median joining network without commonly shared haplotypes supports the same scenario. The genetic homogeneity is probably due to the amphidromous life history providing the opportunity for passive larval transportation among the rivers through coastal currents in eastern Taiwan. The endemism to eastern Taiwan may be a consequence of complicated interactions among short pelagic larval duration, interspecific competition and coastal currents.

Life cycle of the dung beetle Onthophagus cervus (Fabricius, 1798) (Coleoptera: Scarabaeidae: Scarabaeinae) in moist belts of south India

Biology, nesting behaviour, and the factors favouring the high abundance of prominent dung beetle species, Onthophagus cervus (Fabricius, 1798) in an open agricultural field in North Kerala were studied. Short life cycle with high fecundity, low egg mortality, shorter larval duration, shorter developmental period, short generation time, female-biased sex ratio, and longer survivability of females were recorded. Female-biased sex ratio in O. cervus indicates that mating competition takes place between male offsprings and the high cost of producing males led to their reduction. Broad categorization of Onthophagus species is provided based on the comparison of data of brood mass production, fecundity, duration of egg, larval, pupal, adult stages, adult mortality and life span of various Onthophagus species. Higher abundance of O. cervus in the region is attributed to traits that are characterize of r-selection such as high fecundity, small body size, low egg mortality, shorter larval duration, early onset of maturity, and shorter developmental period. Short generation time which enables attaining maturity earlier together with female biased sex ratio, longer duration of females favouring high egg production and shallow tunnels which enable easy and fast tunnelling process and development in thin soil top soil layer are the other factors that contributed to the higher abundance of O. cervus. Present study showed that geographic region wise knowledge on the life history traits of prominent dung beetles are necessary for interpretation of the exact mechanism behind their seasonality and abundance in specific regions and the generated data will be useful for the conservation of species in natural habitats.

Performance of Double Hybrid of Silkworm (Bombyx mori L.) Fed on Leaf Raised under Different Fertilizer Schedules

Aim: The present study was aimed to see the performance of silk worm (Bombyx mori L.) double hybrid fed on leaf raised through splitting the recommended dose of chemical fertilizers. Study Design: Completely Randomized Design (CRD). Place and Duration of Study: College of Temperate Sericulture (CoTS) Mirgund, Sher-e-Kashmir University of Agricultural Sciences and Technology of Kashmir (SKUAST-K), during 2017 and 2018. Methodology: The present investigation was carried out at the experimental farm of College of Temperate Sericulture-Mirgund. Goshoerami a popular variety of mulberry in the region was used for the study. Disease free layings (dfl’s) of the popular double hybrid were obtained from the Germplasm Bank maintained at College of Temperate Sericulture (CoTS) Mirgund. These dfl’s were incubated, brushed and reared up to 3rd instar en masse following the standard rearing procedure. After 3rd moult, 3 replications of 100 larvae in each treatment were maintained. Different larval and Cocoon parameters were recorded during the course of experimentation. Standard procedure was followed to record observations. The data was compiled and analyzed. Results: T11 recorded the shortest values for total larval and fifth instar larval duration being statistically at par with treatments/ fertilizer schedules T12, T9, T10, T3, T4, T1, T2 and T7. Weight of ten mature larvae was recorded higher in treatment T14 being statistically at par with treatments T13, T16 and T15 respectively. Cocoon yield per 10,000 larvae by number was recorded highest In T14 treatment, which was recorded statistically at par with treatments T13 and T16 respectively. Cocoon yield by weight was more in treatment T14 being at par with treatments T13 and T16. Pupation rate was found higher in treatment T14 being at par treatment T13. Conclusion: Double hybrid performed better under parameters like- total as well as fifth instar larval duration in case of fertilizer schedule - T11 (N3P2K1), while as in case of larval weight, cocoon yield by number and by weight and pupation rate, the hybrid performed better under T14 (N4P1K2) fertilizer Schedule.

Dynamic larval dispersal can mediate the response of marine metapopulations to multiple climate change impacts

Climate change is having multiple impacts on marine species characterized by sedentary adult and pelagic larval phases, from increasing adult mortality to changes in larval duration and ocean currents. Recent studies have shown impacts of climate change on species persistence through direct effects on individual survival and development, but few have considered the indirect effects mediated by ocean currents and species traits such as pelagic larval duration. We used a density-dependent and stochastic metapopulation model to predict how changes in adult mortality and dynamic connectivity can affect marine metapopulation stability. We analyzed our model with connectivity data simulated from a biophysical ocean model of the northeast Pacific coast forced under current (1998-2007) and future (2068-2077) climate scenarios in combination with scenarios of increasing adult mortality and decreasing larval duration. Our results predict that changes of ocean currents and larval duration mediated by climate change interact in complex and opposing directions to shape local mortality and metapopulation connectivity with synergistic effects on regional metapopulation stability: while species with short larval duration are most sensitive to temperature-driven reduction in larval duration, the response of species with longer larval duration are mostly mediated by changes in both the mean and variance of larval connectivity driven by ocean currents. Our results emphasize the importance of considering the spatiotemporal structure of connectivity in order to predict how the multiple effects of climate change will impact marine populations.

Networks of marine protected areas under fluctuating connectivity: The importance of within-MPA dynamics

The design of marine protected areas (MPAs) has been optimized under assumptions of spatially and temporally homogeneous larval dispersal, despite complex spatiotemporal patterns displayed by ocean currents. Here we studied the effect of dispersal variability on the effectiveness of MPA networks across scales. We adopted a nested approach integrating the dynamics of both within and among MPA connectivity into a stochastic metapopulation model and first derived metapopulation persistence (required reproductive effort) and stability over MPA networks by partitioning within and among MPA contributions in relation to the spatial resolution of within-MPA connectivity. We applied this framework over a range of dispersal traits (spawning time and pelagic larval duration) and MPA network configurations, based on simulated biophysical connectivity along the northeast Pacific coast. Our results show how within-MPA dynamics affect predictions based on parameters of MPA networks such as MPA size, spacing, and pelagic larval duration. Increasing within-MPA spatial resolution predicted increasing population persistence and stability independently of other network properties. High-resolution within-MPA dynamics also predicted a negative relationship between species persistence and MPA spacing while that relationship was non-monotonic under low-resolution within-MPA dynamics. Our analysis also resolved the role of pelagic larval duration for scaling up within-MPA dynamics to MPA networks: species with short larval duration led to increasing network stability with MPA spacing while the opposite was observed for species with long larval duration. Our study stresses the importance of integrating fluctuating larval connectivity, both within and among MPAs, and more specifically suggest the benefit of small and nearby MPAs under increasing ocean variability.