Mackerel (Scomber australasicus) Reproduction in Northeastern Taiwan

Blue mackerel (Scomber australasicus) is a crucial target species for coastal fisheries in Taiwan, and additionally it has maintained its status as the highest-produced species. The timely measurement of spawning status is crucial for determining the correct management strategy for this species. The objective of this study was to determine size at maturity, fecundity, batch fecundity, and spawning frequency on the basis of samples collected from Nan-Fang-Ao fishing port in Yilan, during the spawning season from 2017 to 2019. Histological sections indicated that the blue mackerel were multiple spawners; a higher percentage of female fish spawned at the peak of the gonadosomatic index. The 50% sizes at maturity were 32.02, 32.13, and 29.64 cm. Mean total fecundity (batch fecundity) was 165 (103), 229 (96), and 210 (68) oocytes per ovary-free weight (g) for 2017, 2018, and 2019, respectively; fecundity was determined through observation of postovulatory follicles (POFs). The spawning frequencies (spawning fraction) in 2017, 2018, and 2019 were 3–10 days (0.13), 4–14 days (0.08), and 4–12 days (0.09), respectively. The spawning frequencies determined through the three estimated methods, namely the sums of (a) hydrated and Day 0 POFs; (b) Day 1+ POFs, and (c) all data combined, were 1 spawning event per 8, 10, and 9 days, respectively. The reproduction of the blue mackerel was greater in 2017 than it was in 2018 or 2019, as indicated by the higher batch fecundity and shorter spawning seasons. Environmental factors should also be considered as a major factor influencing successful reproduction and spawning season

Fitness benefits of dietary restriction

Dietary restriction (DR) improves survival across a wide range of taxa yet remains poorly understood. The key unresolved question is whether this evolutionarily conserved response to temporary lack of food is adaptive. Recent work suggests that early-life DR reduces survival and reproduction when nutrients subsequently become plentiful, thereby challenging adaptive explanations. A new hypothesis maintains that increased survival under DR results from reduced costs of overfeeding. We tested the adaptive value of DR response in an outbred population of Drosophila melanogaster fruit flies. We found that DR females did not suffer from reduced survival upon subsequent re-feeding and had increased reproduction and mating success compared to their continuously fully fed (FF) counterparts. The increase in post-DR reproductive performance was of sufficient magnitude that females experiencing early-life DR had the same total fecundity as continuously FF individuals. Our results suggest that the DR response is adaptive and increases fitness when temporary food shortages cease.

Some Aspect Biology Reproduction of the Indonesian Predatory Catfish (Wallagonia leerii Bleeker, 1851) in Sebangau River Central Kalimantan

Tapah fish (Wallagonia leerii) is one of the economically valuable and popular fish species because its large size and make it the main target for fishing in the Sebangau River. It is feared that excessive exploitation of these fish can cause a decline and threaten the sustainability of tapah fish, which up to now still depend on nature. This research aimed to describe reproductive biology of tapah fish related to sex ratio, gonad maturity, gonado-somato index and fecundity. A total of 96 fish samples were collected using fishing trap and seine net for three months at five sampling sites in Sebangau River. The results showed that the sex ratio of male and female for all samples were 1:0.9 and Chi-square test with a 95% confidence interval showed approaching to 1:1 ratio. The GSI value of male and female ranged from 0,110% – 0,522% and 0,112% – 0,651%. The spawning times were recorded from Desember to January. The total fecundity of 11 female ranged from 2976 to 155501 eggs with an average of 43334 eggs.

Biological Parameters of the Bark Beetle, Xylosandrus crassiusculus (Motschulsky) Under Controlled Laboratory Conditions

Biological parameters of the bark beetle, Xylosandrus crassiusculus (Motschulsky) (Coleoptera: Curculionidae: Scolytinae) was investigated under different temperature regimes (27, 29, 31 and 35ºC). The females reared at 29°C, lived 30.93±2.36 days for oviposition. The female laid a maximum of 6.71±1.89 eggs per day and a maximum of 6.99±1.33 batches per female. Each batch had an average of 13.78±2.01 eggs. The mean total fecundity recorded was 67.8±4.25 eggs, with a shortest egg incubation period. At 29°C, the duration of the larval stage was 20.17±2.89 days, the pupal stage 5.03±1.11 days, and the life span of the adult insect was 29.44±3.19 days. Significant differences (P<0.05) were noted when the duration of the different life stages under 29 and 35ºC were compared, with longer duration at 29°C. Insects reared at 35°C had narrower bodies and smaller sizes. Furthermore, the developmental stages period, including the ovipositional period (days) were negatively correlated with temperature. Keywords: Xylosandrus crassiusculus, bark beetle, biological parameters, temperature regimes.

Influence of selected biogenic amines on development and demographic parameters of a temperate population of Cinara (Cupressobium) cupressi (Hemiptera, Aphididae)

Cinara (Cupressobium) cupressi, the cypress aphid, is a serious pest of Cupressus spp. and other Cupressaceae, considered to be one of the world’s 100 worst invasive alien species. The potential influence of selected biogenic amines (tryptamine, tyramine, putrescine, and cadaverine) on development and demographic parameters of a temperate population of the cypress aphid was investigated under laboratory conditions. Within parthenogenetic generations, the use of biogenic amines resulted in a significant reduction in the total fecundity and the average daily fecundity both in the fundatrix (F0) and the fundatrigeniae (F1), whereas this influence in the F5 generation was insignificant. In all parthenogenetic generations treated with amines, the dissected female abdomen contained a greater number of mature embryos compared to control samples. Cadaverine caused marked changes in the body length of all viviparous generations studied and a significant reduction in the number of developing embryos, compared to the control sample. The use of biogenic amines did not significantly affect the number of eggs produced by oviparous females but had an impact on their lifespan. Our results indicate that biogenic amines application may disrupt feeding behavior and thus leads to reduced fecundity, consistent with the observation of reduced embryo production. Consequently, bioamines can be used as an alternative agents to control this important pest species.

Reproductive biology of the anchovy (Stolephorus commersonnii, Lacepède, 1803) and spotted sardine (Amblygaster sirm, Walbaum, 1792) from Tanga Region, Tanzania

The present study investigated the reproductive biology of Stolephorus commersonnii and Amblygaster sirm at two landing sites in Tanga on the northern coast of Tanzania. Fish samples were collected on a monthly basis from ringnets operated by artisanal fishers in the nearby coastal waters. Spawning seasons were determined using gonadosomatic index (GSI) and gonadal maturity stages. The size at first maturity was 57.7 mm and 66.2 mm total length for male and female S. commersonnii respectively. Male and female A. sirm were estimated to attain first maturity at 147.7 mm and 169.2 mm respectively. The spawning seasons of both species were protracted. S. commersonnii demonstrated a year round spawning cycle with peaks in August, October and January. The peak spawning season for male and female A. sirm was recorded in August and September respectively. Both species exhibited skewed size-dependent sex ratios with females predominating in the larger size classes. A. sirm had a higher fecundity rate with a maximum of 96,500 eggs in the largest female fish of 258 mm as compared to S. commersonnii (10,055 eggs) in the largest fish of 98 mm. The mean (±SE) total fecundity of S. comersonnii and A. sirm was 5,134.7 ± 136.9 eggs, and 47,029.03 ± 1,435.13 eggs in females of sizes 68 mm to 98 mm and 170 mm to 258 mm respectively.

Development and life history parameters of Typhlodromus recki (Acari: Phytoseiidae) feeding on Tetranychus urticae (Acari: Tetranychidae) at different temperatures

Typhlodromus recki (Acari: Phytoseiidae) was collected from aubergines, pepper, black nightshade and jimsonweed plants infested with spider mites from a pesticide-free vegetable garden in Denizli, Turkey. The biology and life table parameters for T. recki feeding on Tetranychus urticae (Acari: Tetranychidae) at different temperatures (15, 20, 25, 30 and 35 °C) were determined. The results showed that total preadult periods of T. recki at 15, 20, 25, 30 and 35 °C were 19.6±0.51, 9.4±0.16, 7.6±0.14, 5.7±0.14 and 4.5±0.08 days, respectively. The longest oviposition period was 23.5 days at 20 °C. Total fecundity of T. recki significantly differed between the constant temperatures and the highest was observed at 20 °C (28.6 eggs/female) and 25°C (23.5 eggs/female). Although females survived for 26 days at 35 °C, only four females laid eggs for 1 day. Thus, 35 °C is not suitable for the reproduction of T. recki. Total longevity of female was the longest at 15°C (59.5 days) and 20 °C (51.3 days) whereas male total longevity was the longest at 15°C (53.2 days). The intrinsic rate of increase (r) and finite rate of increase (λ) were numerically the highest at 30 °C (0.17 and 1.18 d-1), but there was no statistical difference observed between 25 and 30 °C for both r and λ values. The net productive rate was significantly highest at 20, 25 and 30 °C. The longest mean generation time occurred at 15 °C (42.6 days) and the shortest was at 35 °C (8.0 days). After some field trials, Typhlodromus recki could potentially be considered in the biological control agent of T. urticae.

First Findings of Sunbleak Leucaspius delineatus (Cyprinidae) in the Lake Baikal Basin

Since the early 1960s, the sunbleak Leucaspius delineatus (Heckel, 1843), along with carp acclimatized from European Russia, regularly entered the siberian carp ponds, first in the Ob’ basin, and then in the Yenisei and Angara basins. In the last decade, we have discovered the sunbleak in two water bodies of the Baikal basin: in May 2013 - in the water intake and discharge canals of the Gusinoozersk regional power plant situated on the large lake Gusinoe in the Selenga River basin (Republic of Buryatia), and in November 2016, the sunbleak was registered in the diet of pike inhabiting the reservoirs of the Talaya-Pokhabikha lake-bog complex in the immediate vicinity of the Baikal coastline at the southern end of the lake in Irkutsk Region. The age series in the samples of the sunbleak in the water intake canal of the power plant was represented by five age groups from 1+ (SL 34.2 mm and 0.59 g of weight) to 5+ (SL 73.9 mm and 6.73 g, respectively) with a predominance of individuals aged 1+ and 2+. In the discharge canal only group 1+ (SL 35.5 mm and 0.69 g) was noted. The sex ratio in catches at the age of 1+ was 1:1.2 with a predominance of males; by the age of 3+, the proportion of males increased significantly (1:8.6). Sexual maturity of the sunbleak from Lake Gusinoe occurs at the age of 3+. Spawning is portioned, the first portion is layed down not earlier than the second half of July. The total fecundity of the seven studied females at the age of 3–5 + varies from 632 to 1539 eggs, averaging 1312 eggs. The sunbleaks from Lake Gusinoe are predominantly benthophagous. In the first half of May 2013, near the water intake canal, the main food components were the nymphs of the Corixidae water bugs and larvae of Phryganea caddis flies, planktonic crustaceans and imago of aerial insects were also consumed. In July 2014, in the discharge channel, the main food item was the chironomid larvae. In the lake Sludyanskoye, three specimens were identified from the stomachs of the pike living there. All fish were partially digested, and therefore it was not possible to analyse it.

Caloric restriction extends lifespan of mothers at the expense of offspring survival in a predatory mite (Neoseiulus cucumeris)

The extension of lifespan by means of calorie restriction (CR) is one of the most replicable mechanisms across a range of different taxa. However, the effects of this on the next generation are less studied due to the complexities associated with such an experiment. In this study, the effects of CR and ad libitum (AL) feeding on lifespan, duration of ovipositional stages, and fecundity of a predatory mite, Neoseiulus cucumeris were investigated. The egg volume, sex ratio, and survival rate of the offspring were then compared across the different treatments. The three treatments were: (1) 40 prey Tyrophagus putrescentiae eggs per day representing the AL treatment; (2) 10 eggs per day representing medium CR; and (3) 5 eggs per day being high CR. To assess for transgenerational effects, the eggs produced under the three different treatments were fed AL and reared until adulthood or death. Mothers under the medium CR treatment had a lifespan that almost doubled the lifespan of mothers fed AL. Contrastingly, a higher reproductive rate was seen in mothers under AL, which also had a significantly higher total fecundity when compared with both CR treatments. The AL mothers had a shorter gestational period and produced larger eggs. There was no difference between the sex ratio of offspring for the medium CR and AL treatments. These results indicate the different effects of the two levels of CR and highlight the trade-offs that are accompanied with a longer lifespan due to caloric restriction.

Demographic analysis of sublethal effects of propargite on Amblyseius swirskii (Acari: Phytoseiidae): Advantages of using age-stage, two sex life table in ecotoxicological studies

Knowledge of the impact of acaricides on predatory mites is crucial for integrated pest management (IPM) programs. The sublethal effect of propargite was assessed against the subsequent generation of treated Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) fed on Tetranychus urticae Koch (Acari: Tetranychidae) under laboratory conditions [26 ± 1 ̊C, 70 ± 3 % RH and 16:8 (L:D) h]. A leaf disc bioassay was employed to assess the sublethal concentrations (LC10, LC20, and LC30) of propargite (Omite® 57% EC, MAHAN, Iran) on A. swirskii. The results revealed that sublethal concentrations of propargite significantly affected the total life span and longevity of the treated females of A. swirskii. Reproductive and total fecundity of the subsequent generation were also affected by sublethal concentrations. All concentrations caused a significant reduction in oviposition days, compared to the control. The intrinsic rates of increase (r) of A. swirskii treated with sublethal concentrations of propargite and distilled water were 0.126, 0.122, 0.115, and 0.129 d-1, respectively. Our findings revealed that propargite had no significant effect on life table parameters of treated mites in comparison to the control. Sublethal effects of propargite and its impact on A. swirskii are discussed.