The host plant-mediated impact of simulated acid rain on the development and reproduction of Tetranychus cinnabarinus (Acari, Tetranychidae)

Abstract:  The host plant-mediated impact of simulated acid rain (pH 3.0, 3.5, 4.0, 5.6, and 6.8) on the behaviour, development, and reproduction of carmine spider mite, Tetranychus cinnabarinus (Boisduvals), were evaluated at 25°C in a series of laboratory trials. The results indicated that the adults of carmine spider mite prefer to aggregate on pH 4.0 acid rain-treated eggplant leaves. The developmental times of nymph, larva and the pre-oviposition period of the mite on kidney bean leaves were significantly affected by acid rain treatments. The developmental times for the immature stages ranged from 11.4 days on pH 4.0 acid rain-treated leaves to 12.7 days on other acid rain-treated leaves. The survival of immatures varied from 85.14% on pH 4.0 acid rain-treated leaves to 78.83% on deionized water-treated leaves (pH 6.8). The mites feeding on acid rain-treated leaves (pH 3.0–5.6) had significantly greater reproductivity and longevity than those feeding on deionized water-treated leaves. The average greatest reproductivity (74.6 eggs per female) and longest female longevity (8.9 days) were recorded on pH 4.0 acid rain-treated leaves. Accordingly, the intrinsic rate of increase ( r _m ) for the mite on pH 4.0 acid rain-treated leaves was the highest. Jackknife estimates of r _m varied from 0.201 on pH 4.0 acid rain-treated leaves to 0.158 on pH 5.6 acid rain-treated leaves. The results implied that the population growth of the mite were enhanced by application of acid rain (pH 3.0–5.6) on host plants.     

Parthenogenesis in Urechis caupo (Echiura) II. Role of intracellular pH in parthenogenesis induction

A peptide (P23) isolated from sperm acrosomal protein initiates development in eggs of the marine worm Urechis caupo . We have shown previously that eggs exposed to P23 for ≥3min complete meiosis but fail to cleave. However, a brief (1.5–2 min) exposure to P23 at pH 8, followed by either acidification of the seawater to pH 7 or dilution of P23 at pH 8 causes germinal vesicle breakdown (GVBD), but eggs fail to complete meiosis and many then later advance to mitosis. In the present study we investigated the hypothesis that partial activation leading to parthenogenesis occurs when there is a partial intracellular alkalinization. Measurements with the fluorescent pH indicator bis(carboxyethyl)-carboxyfluorescein (BCECF) showed that P23 induces a pH, increase similar to that occurring during fertilization and that parthenogenesis-inducing treatments interupt this rise in pH₁ In eggs exposed to P23 for >3 min the pH₁ increase was 0.31–0.49 units, slightly higher than in fertilized eggs. In partially activated eggs exposed to P23 for 1.5–2 min at pH 8, pH₁ began to rise but then returned to control values or remained only partially elevated (< 0.2 pH units average increase). Electrophysiological measurements revealed that removal of P23 during the first few minutes of exposure caused the activation potential to terminate and experiments with [¹⁴C]-P23 confirmed that dilution results in a rapid unbinding of P23 from eggs. If proton export is driven by membrane potential as well as the pH gradient, these results explain why dilution of P23 at pH 8 also interrupts the pH_i increase.     

A comparison of zygote survival of native and non-native walleye stocks in two Georgian Bay rivers

Synopsis Poor natural recruitment of a Georgian Bay walleye stock that spawns in the Shawanaga River has been attributed to poor survivorship of early life stages. I investigated whether low zygote survival was part of the problem by conducting an in-situ incubation experiment with artificially fertilized eggs from the Shawanaga and the nearby Magnetawan River stocks. Both rivers have low buffering capacity (5–6.5 mg·l^–1 alkalinity), but moderately low pH (5.5) had only been recorded in the Shawanaga. Zygotes were reared in both rivers. Minimum pH during incubation was 6.2 in the Shawanaga and 6.8 in the Magnetawan River. Mean survival rate to hatching strongly favoured the native stock in both rivers (86 vs. 25 % in the Shawanaga River and 80 vs. 40% in the Magnetawan River), and these differences were statistically significant. The results suggest that viability of Shawanaga zygotes is not a problem, but a low pH effect on zygote survival could not be inferred from the relatively high pH of Shawanaga water in the spring of 1990. The large difference in hatching success between native and non-native stocks was unexpected, and may have been the result of stock-specific adaptation to differing cation: anion and/or metal concentrations in the two rivers, or to some other factor.     

Larval development of carp, Cyprinus carpio L., in acidic water

Laboratory experiments measuring survival and growth at various pH levels and two temperatures indicate that the threshold of pH of water below which larval development of carp is stopped is 5.0–5.2, the development of some individuals being stopped within the pH range 5.0–5.5. Inhibition of development is due to the inability of a larva to fill its swimbladder with air, this preventing swimming and leading to death from starvation. In water of pH 5.5–6.0 the development may be undisturbed, though slower. The effect of water acidification is reflected in slower growth rate and prolongation of the larval stages of development.     

Temperature-dependent development and survival of the lesser mealworm, Alphitobius diaperinus

Abstract. Development, growth and survival of the lesser mealworm, Alphitobius diaperinus (Panzer), were determined at six constant temperatures. No egg hatch or larval development occurred at 17^oC. At temperatures of 20, 25, 30, 35 and 38^oC the median development times (days), respectively, were for eggs (13.4, 6.0, 4.4, 2.6 and 2.6), larvae (133.0, 46.0, 26.2, 22.4 and 23.9), pupae (17.0, 8.0, 5.5, 4.0 and 4.1), and from oviposition to adult emergence (164.4, 60.2, 37.9, 29.0 and 30.8). The Sharpe & DeMichele (1977) model was used to describe the temperature-dependent development. The mean egg survival (hatching) ranged from 61% to 86%, with lowest hatch at 20^oC. Survival of the larvae and pupae ranged from 32% to 73% and from 85% to 95%, respectively, with lowest survival at 20^oC. Pupae had significantly lower weights at 35^oC and adults at 38^oC than at the other temperatures. Female pupae (20 mg) and female adults (16 mg) were significantly heavier than male pupae (17 mg) and male adults (13 mg). Adults (0.5–9 months old) laid 4–7 eggs per female per day at 25^oC.     

The effects of low pH on egg and alevin survival of kokanee and sockeye salmon, Oncorhynchus nerka

1. The effects of low pH water on embryogenesis and vitellogenesis in kokanee and sockeye salmon (Oncorhynchus nerka) were investigated. Eggs were exposed to low pH from fertilization to 45 days post-median hatch or to an episodic exposure at pH 4.0. Adult kokanee were also exposed to low pH just prior to ovulation and spawning. 2. The most sensitive stages of development during chronic or episodic exposure to low pH were early embryonic development and newly-hatched alevins. 3. Incubation of eggs at low pH caused a lower median survival, delayed hatching, higher alevin mortality and reduced the efficiency of yolk conversion to tissue of yolk-sac alevins. Those effects were more pronounced when the eggs were fertilized at low pH. 4. Exposure of sexually mature kokanee salmon to acidified water reduced egg and alevin survival, delayed embryo hatching and decreased the percent hatch. Those effects were more pronounced when their eggs were incubated at low pH.     

Endozoochory by ducks: influence of developmental stage of Bythotrephes diapause eggs on dispersal probability

Abstract. This paper evaluates whether the recent expansion of Bythotrephes longimanus Leydig (Crustacea: Onychopoda) may be a result of endozoochorous avian dispersal. In three experiments, we investigated the survival of diapause eggs in newly produced and end-of-winter developmental stages after their passage through the digestive tract of four species of ducks. Resistance of eggs to digestion was low for both developmental stages (< 12%). Most eggs (67–95%) were recovered by four hours after ingestion, with a longer maximum retention time for newly produced (22 h) than end-of-winter eggs (4–6 h). Ingestion had a detrimental effect on viability: only eggs retrieved one hour after ingestion hatched and the proportion of those ingested that produced viable neonates was low (0.5% for newly produced and 0.3–3% for end-of-winter eggs). We conclude that the probability of endozoochorous dispersal by individual ducks is low but becomes significant when considering the thousands of ducks moving among wetlands. Endozoochorous dispersal of B. longimanus would most likely involve the transport of newly produced diapause eggs from north to south, during the autumn migration of ducks. Based on flight speed estimates of ducks we estimate dispersal probability to drop sharply at distances over 60–80 km.     

Susceptibility of immature stages of Chrysoperla rufilabris (Neurop., Chrysopidae) to pyriproxyfen, a juvenile hormone analog

Effects of pyriproxyfen (Knack), a juvenile analog, at three concentrations (10, 50 and100 mg [AI]/l), on survival and development of all immature stages of Chrysoperla rufilabris (Burmeister), were determined in the laboratory. Pyriproxyfen significantly reduced the survival rates when eggs, first and third instars were treated, but not when the second instars and pupae were treated. When eggs were treated, the two higher concentrations reduced the eggs viability by 33.3–50%, and only 0.0–6.7% developed to adults. The lowest concentration of pyriproxyfen (10 mg [AI]/l) caused high mortality on third instars, not on other stages, indicating the third instar was the most vulnerable stage. Pyriproxyfen had significant effects on development for all immature C. rufilabris that successfully developed to adults with variations among the developmental stages and concentrations. The overall developmental duration from eggs to adults when eggs, first, and third instars were treated were 2.6–4.2, 2.4–4.1 respectively, and 6.0–7.1 d longer than those in water control, respectively. However, the overall developmental durations from eggs to adults were 0.5–1.2 d shorter than in water control when the second instars were treated with pyriproxyfen. The compatibility of pyriproxyfen with natural enemies in integrated pest management programs is discussed.     

Mitotic Asters Separate, although Chromosomes Do Not Separate at Slightly Acidic pHi in the Fertilized Egg of the Sea Urchin, Hemicentrotus pulcherrimus

The effect of slightly acidic intracellular pH (pHi) on the development of the sea urchin, Hemicentrotus pulcherrimus was investigated. At first cleavage, the fertilized eggs were treated with artificial sea water containing sodium acetate (Ac-pHSW) at pH 6.8 or 7.0 at the onset of nuclear envelope breakdown, and their pHi decreased from 7.30 to 6.68 or 6.78, respectively. When the eggs were observed after fixation by indirect immunofluorescence and differential interference contrast microscopy, the mitotic stage of the treated eggs was arrested at metaphase and the mitotic apparatus was maintained until more than 50 min after the treatment, although it was smaller in size than that of non-treated eggs. On the other hand, the number of the mitotic asters increased from 2 to 3-4, and further to 6-8 following prolonged exposure, suggesting that the centrosomes had divided and replicated. These results suggest that the centrosome cycle advanced at slightly acidic pHi, even when the mitotic cycle did not advance beyond metaphase.     

Alterations in pH and Serum Concentration have Contrasting Effects on Normal and "Foreign" Pathways of Differentiation in Cultures of Embryonic Chick Neuroretinal Cells

Nine-day chicken embryo neuroretinal cells transdifferentiate into both lens and pigment cells after 3–4 weeks when cultured in MEM medium containing 10% foetal calf serum at pH 7.4. At pH 6.8. the appearance of lens crystallins is retarded and cholineacetyltransferase (CAT) activity persists for longer, whereas at pH 8.0 crystallins appear earlier and CAT activity declines more rapidly. Cell survival and culture growth are about 10% lower at pH 6.8 than at pH 8.0. If the concentration of foetal calf serum (FCS) is increased from 10% to 25% (at pH 7.4), cell survival and growth are both promoted, crystallins appear slightly earlier and CAT activity declines more rapidly. Converse effects are observed with 5 % serum, accumulation of crystallins being greatly inhibited and CAT activity prolonged. Crystallin production in cultures with 10% or 25% chicken serum (CS) is much less extensive than in similar FCS cultures, but in cultures with 5 % CS, crystallins appear more rapidly, reaching higher levels than in 5 % FCS cultures. However, the pattern of CAT activity in response to different serum levels is similar for both CS and FCS. This might imply the presence of some factor(s) able to stimulate transdifferentiation in FCS, whereas CS can apparently inhibit this process.     

Enhanced ovicidal activity of an oil formulation of the fungus Metarhizium anisopliae on the mosquito Aedes aegypti

Abstract.  The effect of humidity on the activity of Metarhizium anisopliae IP 46 (Metsch.) Sorokin (Hypocreales: Clavicipitaceae) formulated in sunflower oil against Aedes aegypti (L.) (Diptera: Culicidae) eggs was examined. After exposure of eggs at 75% relative humidity (RH) for ≤ 25 days, ovicidal activity was not increased by oil-in-water formulated conidia, hyphal bodies or pure-oil formulated conidia, compared with conidia or hyphal bodies prepared in water only. At optimal > 98% RH, eclosion was ≤ 13.7% after treatment with oil-in-water formulated propagules in ≤ 10% oil, and it was completely inhibited when conidia were applied in pure oil. At 86–100% RH, new conidia were found on eggs treated with oil-formulated conidia and incubated down to 91% RH. Ovicidal activity was still detected at 93% RH and was augmented with increasing humidity and time of exposure of eggs. Eclosion of larvae was distinctly reduced by IP 46 pure-oil formulated conidia after a minimal initial exposure of 3 days at > 98% RH, followed by: (a) a 12-day exposure at 75% RH before submersion in water; (b) a minimal 5-day exposure at > 98% RH and direct subsequent transfer of treated eggs to water, or (c) a minimal daily 20-h exposure at > 98% RH alternating with 4 h at 75% RH for 10 days. We demonstrate that oil-based formulations of conidia of M. anisopliae enhance ovicidal activity at high humidities and conclude that these formulations have potential in the integrated control of Ae. aegypti .     

Influence of process parameters on growth of Clostridium ljungdahlii and Clostridium autoethanogenum on synthesis gas

Effects of initial medium pH and gas flow rate on Clostridium ljungdahlii and Clostridium autoethanogenum in liquid batch, continuous gas fermentations were investigated. Synthesis gas components were supplied at varying flow rates (5, 7.5 and 10 mL/min) for C. ljungdahlii (pH 6.8 and 5.5) and C. autoethanogenum (pH 6.0). Growth on synthesis gas was slower than growth on sugars. For C. ljungdahlii, higher cell densities were achieved at pH 6.8 (579 mg/L) compared to pH 5.5 (378 mg/L). The ethanol concentration at pH 6.8 was also 110% greater than that at pH 5.5. The interaction of flow rate and pH was statistically significant with the greatest acetate production in the 10 mL/min, pH 6.8 treatment. The ethanol to acetate ratios were smaller at lower pH levels and higher flow rates. In C. autoethanogenum fermentations, higher flow rates resulted in greater end product formation with no significant effect on product ratios.     

Survival of released pheasants, Phasianus colchicus, in Ireland

The survival of 250 hand-reared pheasants was assessed by resightings of tagged individuals following their release into an open-roofed pen on an estate in Ireland. The death rates per 10 days after release were approximated as 5.5% during the first 30 days, 11.6% between 31–70 days, 6.0% between 70–240 days and 2.3% between 241–365 days. The birds suffered their highest rate of loss (48.2%) during their first 10 days after leaving the release pen. This emergence-related mortality was the major factor influencing changes in the observed death rate following release. Predators, mainly foxes, were initially attracted to the area by the presence of inaccessible prey. Males suffered a higher rate of loss following their emergence from the release pen than did the females, possibly associated with the greater proportion of time thereafter spent outside the pen and hence at risk. The factors affecting the survival of hand-reared pheasants are discussed. It is suggested that reducing densities of birds within pens may increase subsequent survival without resorting to predator control.     

Biology of Triatoma pallidipennis stal 1945 (Hemiptera: Reduviidae:Triatominae) under laboratory conditions

Aspects related to hatching, life time, mortality, feeding behaviour and fecundity for each stage of Triatoma pallidipennis life-cycle were evaluated. The hatching rate observed for 200 eggs was 60% and the average time of hatching was 18 days. Eighty nymphs (N) (40%) completed the cycle and the average time from NI to adult was 168. 7+/-11.7days. The average span in days for each stage was 18.0 for NI, 18.5 for NII, 30.0 for NIII, 35.7 for NIV and 50.1 for NV. The number of bloodmeals at each nymphal stage varied from 1 to 5. The mortality rate was 9.17 for NI, 5.5 for NII, 6.8 for NIII 4.17 for NIV and 13.04 for NV nymphs. The average number of eggs laid per female in a 9-month period was 498.6. The survival rates of adults were 357+/-217.9 and 262.53+/-167.7 for males and females respectively.     

pH in the Jelly Layer of Starfish Oocytes

Using liquid ion exchanger micro-electrodes we have studied the pH in the vicinity of starfish oocytes and eggs and also in their jelly layers. Although highly variable, the pH in these zones was consistently lower (6.3–7.6) than the pH of sea water (7.8–8.2). Aged oocytes/eggs presented more acid environments than fresh oocytes. The pH indicator Phenol Red shows that the ovarian fluid is more acid than seawater, ranging from 6.0 to 7.5. Our data suggests that starfish oocytes, from their time in the ovary until several hr after their release, are surrounded by an acid environment. This micro-environment may play a role in metabolic repression in the ovary and in the regulation of sperm-egg interaction following spawning.     

Effects of gamma irradiation used to inhibit potato sprouting on potato tuber moth eggs Phthorimaea operculella Zeller (Lep., Gelechiidae)

Abstract: Different age groups of potato tuber moth, Phthorimaea operculella Zeller, eggs were exposed to gamma irradiation at incremental doses up to 150 Gy (the upper dose limit allowed for potato sprout inhibition). Young eggs were more likely to be sensitive to gamma irradiation than older eggs and the sensitivity level declined with age of the eggs. The exposure of 3–3.5-day-old eggs to 150 Gy resulted in a 26% increase in the egg incubation period compared with unirradiated eggs. The minimum dose required to prevent 4–4.5-day-old eggs from hatching was 1 kGy. When eggs were exposed to 75 Gy, 9.7% of larvae survived to the adult stage but emerged as deformed moths. At 100 and 125 Gy, 10.2 and 9.6% of larvae pupated, respectively, although no adult eclosion was recorded, whereas at 150 Gy, the larvae remained in mid-instar stage and eventually died. Gamma irradiation doses applied to inhibit potato sprouting could be also considered as a valuable control tool against potato tuber moth infestations.     

Some effects on the growth of brown trout from exposure to aluminium at different pH levels

Yearling brown trout, Salmo trutta L., were exposed to various concentrations of inorganic aluminium (0–3.7 μM1⁻¹) over a pH range of 4.3–6.5 in a flow-through bioassay apparatus using synthetic test media. Low pH, in the absence of aluminium, produced little effect on growth or survival except at the lowest pH tested (4.3). At pH less than 5.5, concentrations of total aluminium in excess of 1 μM 1⁻¹ (27μg 1⁻¹) were found to retard growth. The effects of a given aluminium concentration were markedly reduced at pH above 5.5.
The change in aluminium toxicity with pH must be related to changes in aluminium chemistry. When growth rates are correlated with the different aluminium species, calculated using thermodynamic equilibrium constants given in the literature, it appears that the Al(OH)^{2 +} species is the most toxic, with a small contribution also coming from polymeric complexes.     

Seasonal reproductive cycle in relation to tolerance to high temperatures in the terrestrial slug Lehmannia valentiana

Abstract. Seasonal maturation of the gonad (hermaphrodic gland) was examined in the terrestrial slug Lehmannia valentiana in Osaka, Japan. The ratio of the gonad weight to body weight was low in June–September, rapidly increased in October, and gradually decreased thereafter. In May–September, most slugs had only spermatogonia and spermatocytes, and all slugs had mature sperms in October–April. The oocyte size increased in September and large oocytes were observed in late October–April. Under natural temperature and photoperiodic conditions in Osaka, slugs laid eggs in early November–May. Therefore, this species reproduces from late autumn to spring, in contrast to many terrestrial slugs. In January–early February, however, the number of laid eggs was small and oviposition activity showed a bimodal seasonal pattern. In contrast, the hatching pattern was unimodal and most hatching was observed in spring. After a 1-h exposure to 33°C, the survival rate was 100% in juvenile slugs but 0% in eggs. Although hatching success was >85% at 15°–20°C, no eggs hatched when they were maintained at 25°C. The heat susceptibility of eggs in this species may be one of the key factors restricting oviposition from late autumn to spring.     

Development of eggs and larvae of the flounders Rhombosolea tapirina and Ammotretis rostratus (Pisces: Pleuronectidae)

The stages of development of laboratory-reared eggs and larvae of Rhombosolea tapirina and Ammotrelis rostratus are described. They both exhibited á typical pleuronectid pattern of development. At ambient seawater temperature of 11.1–13.8° C R. tapirina eggs hatched 83–93 h after fertilization and larvae metamorphosed c. 65 days later at mean length of 8.83 mm. Hatching of A. rostratus eggs occurred 93–105 h after fertilization and larvae metamorphosed after c. 69 days (mean length 11.21 mm) at 12.7–16.5° C. The two species can be readily separated by their morphology, meristics and pigmentation. In particular, the eggs differ in diameter, only R. tapirina larvae possess a pair of spines in the otic region, and juvenile A. rostratus have only a left pelvic fin.