Effects of <Emphasis Type="Italic">Euseius stipulatus</Emphasis> on establishment and efficacy in spider mite suppression of <Emphasis Type="Italic">Neoseiulus californicus</Emphasis> and <Emphasis Type="Italic">Phytoseiulus persimilis</Emphasis> in clementine

The two-spotted spider mite, Tetranychus urticae, is one of the most problematic phytophagous pests in Spanish clementine orchards. The most abundant predatory mites in this ecosystem are Euseius stipulatus, Phytoseiulus persimilis and Neoseiulus californicus. Euseius stipulatus is dominant but poorly adapted to utilize T. urticae as prey. It mainly persists on pollen and citrus red mite, Panonychus citri. A recent study suggested that the more efficacious T. urticae predators P. persimilis and N. californicus are negatively affected by lethal and non-lethal intraguild interactions with E. stipulatus. Here, we investigated the potential of N. californicus and P. persimilis to colonize and thrive on young clementine trees infested by T. urticae in presence and absence of E. stipulatus. Presence of E. stipulatus interfered with establishment and abundance of P. persimilis and negatively affected the efficacy of N. californicus in T. urticae suppression. In contrast, the abundance of E. stipulatus was not affected by introduction of a second predator. Trait-mediated effects of E. stipulatus changing P. persimilis and N. californicus behavior and/or life history were the most likely explanations for these outcomes. We conclude that superiority of E. stipulatus in intraguild interactions may indeed contribute to the currently observed predator species composition and abundance, rendering natural control of T. urticae in Spanish clementine orchards unsatisfactory. Nonetheless, stronger reduction of T. urticae and/or plant damage in the predator combination treatments as compared to E. stipulatus alone indicates the possibility to improve T. urticae control via repeated releases of N. californicus and/or P. persimilis.     

Cold storage and cryopreservation of hairy root cultures of medicinal plant <Emphasis Type="Italic">Eruca sativa</Emphasis> Mill., <Emphasis Type="Italic">Astragalus membranaceus</Emphasis> and <Emphasis Type="Italic">Gentiana macrophylla</Emphasis> Pall.

To explore the possibility of an effectively long-term preservation of the germplasm of the HR lines of medicinal plant Astragalus membranaceus, Gentiana macrophylla Pall., and Eruca sativa Mill., both cold storage and cryopreservation approaches were attempted and compared. After 5-month cold storage on half strength Murashige and Skoog (1962) (1/2 MS) agar medium (AM), up to 82.9, 75.7, and 100% of the A. membranaceus, G. macrophylla and E. sativa hairy roots (HRs) recovered growth, respectively. The survival rates of A. membranaceus and G. macrophylla HRs significantly decreased, whereas that of E. sativa HR was unchanged with the addition of increased levels of exogenous abscisic acid (ABA) during cold storage. Using the encapsulation–vitrification (EV) method for cryopreservation, the G. macrophylla HRs died, whereas up to 6 and 73% of the A. membranaceus and E. sativa HRs survived, respectively. The HR lines evaluated with both methods showed no significant differences in morphology and growth rate compared with controls that were not subjected to preservation methods. These results suggest that cold storage is a more suitable alternative for the HR lines of the three studied plant species and that specificity of plant species have profound effects on the effectiveness of preservation.     

Effect of predator exposure on the performance and survival of red drum (<Emphasis Type="Italic">Sciaenops ocellatus</Emphasis>)

The influence of predator exposure on the survival of hatchery red drum, Sciaenops ocellatus was investigated under laboratory conditions. Several prey-capture (attack distance, mean attack velocity, capture time, and gape cycle duration) and anti-predator (reaction distance, response distance, mean velocity, and maximum velocity) performance variables were quantified using high-speed video for juvenile red drum (25–30 mm standard length, L _S ) reared with and without predators (pinfish, Lagodon rhomboides). Univariate contrasts of prey-capture events demonstrated that attack distance (mean ± s.e.) was significantly greater in red drum reared with (1.20 ± 0.16 mm) versus without (0.65 ± 0.09 mm) pinfish predators. During anti-predator events, red drum reared with predators had approximately 300% greater reaction distance and 20%–30% greater response distance, mean velocity and maximum velocity versus fish reared without predators; however, these differences were not statistically significant. Following video assessments, a series of mortality experiments were conducted using free-ranging pinfish predators. Mortality rates (Z) ranged from 0.047 to 0.060 (Z/hr/predator) and did not differ significantly among treatments.     

The influence of predator regime on reproductive traits in <Emphasis Type="Italic">Gammarus</Emphasis> <Emphasis Type="Italic">pulex</Emphasis> populations

Selection on traits conferring reduced predation may be opposed by selection on other traits associated with reproduction. Here, we examined the hypothesis that traits associated with reproduction in Gammarus pulex are driven by predation. We studied G. pulex originating from ponds with two different kinds of predator regimes: (1) ponds with fish—often large, non-gap-limited predators and (2) ponds without fish where invertebrates are the dominant predators—often small, gap-limited predators with a much more restricted prey size range. We examined the body size of males and females in G. pulex amplexus pairs originating from fish and fishless ponds. We also examined, in the laboratory, their mating success, the number of offspring per female and offspring mortality under different rearing conditions, with or without fish cue. Mating success, defined as the percentage of amplexus pairs that produced live offspring, was higher for G. pulex from fishless ponds independent of rearing condition. Individuals from fish ponds were larger and they produced a higher number of offspring which tended to be related to female body size. Offspring mortality was higher in populations from fish ponds compared to populations from fishless ponds. Despite the higher offspring mortality, females from fish ponds had a higher number of offspring alive after 13 weeks, which is the approximate time it takes for G. pulex to reach maturity. Our data imply that no trade-off between reducing body size to reduce mortality caused by fish and maximising reproductive success exist in G. pulex from fish ponds. The strategy with many offspring may be the correct strategy in fishponds where predation pressure generally is higher than in fishless ponds.     

Density-mediated indirect effects of a common prey tadpole on interaction between two predatory bugs: <Emphasis Type="Italic">Kirkaldyia deyrolli</Emphasis> and <Emphasis Type="Italic">Laccotrephes japonensis</Emphasis>

This paper suggests that the nymphs of a specialist predator, Kirkaldyia (=Lethocerus) deyrolli (Belostomatidae: Heteroptera), are indirectly affected by their tadpoles’ prey. K. deyrolli nymphs and the predator Laccotrephes japonensis (Nepidae: Heteroptera) adults coexist in rice paddy fields. It was predicted that the difference in tadpole density may influence the K. deyrolli nymph survival rate. We first compared survival rates of the first instar nymphs of K. deyrolli in June (high tadpole density period) and July (low tadpole density period). Secondly, we investigated the survival rate of K. deyrolli nymphs at different tadpole densities and under the presence or absence of L. japonensis adults to examine whether higher tadpole density moderates predation pressure from L. japonensis adults to K. deyrolli nymphs, e.g., density-mediated indirect effects. As a result of the comparison, the survival rate of K. deyrolli nymphs in June was higher than that in July. For the field experiment, the slopes between the survival rate of K. deyrolli nymphs and tadpole density were positive under both predator presence and absence. However, the slope under the presence of a predator was steeper than that under absence of the predator (“predator-by-tadpole density interaction” was significant). These results suggest that a higher tadpole density in June provides an abundant food resource for K. deyrolli nymphs and also moderates predation pressure from L. japonensis.     

Cryopreservation of <Emphasis Type="Italic">Robinia</Emphasis><Emphasis Type="Italic">pseudoacacia</Emphasis>

Cryopreservation of Robinia pseudoacacia explants by vitrification achieved 78% survival following the stepwise preculture of shoot tips in (0.3 + 0.5 + 0.7 M) sucrose with a 80 min incubation in PVS2; compared to 87% survival after desiccation of explants to 30% water content, following 3 days alginate bead (with glycerol and sucrose treatments) preculture in 0.7 M sucrose.     

Negative Evidence of <Emphasis Type="Italic">Wolbachia</Emphasis> in the Predaceous Mite <Emphasis Type="Italic">Phytoseiulus persimilis</Emphasis>

The cytoplasmically inherited bacterium Wolbachia is widespread in arthropod species and has been repeatedly detected in the predaceous mite Phytoseiulus persimilis. Our original goal was to assess the prevalence of Wolbachia infection in P. persimilis and the potential fitness consequences for this host. To accomplish that goal, seven P. persimilis strains were obtained from Europe, Africa and the USA and reared on the phytophagous mite Tetranychus urticae as prey. After preliminary results showed that the T. urticae used was infected with Wolbachia, the minimum starvation time of the predators to prevent false positive results from undigested prey was determined. We tested DNA samples by PCR (polymerase chain reaction) after starving the predators or feeding them Wolbachia-free T. urticae for various periods. Those experiments showed that Wolbachia could not be detected after 16 h at 25 °C and 48 h at 20 °C. To verify the results of the PCR analyses, we furthermore conducted crossing experiments with antibiotic-treated and untreated individuals. No indications of Wolbachia effects were recorded. Additionally, we screened live eggs of four of the seven strains reared in our laboratory and alcohol samples of 10 other P. persimilis strains for the occurrence of Wolbachia by PCR, none of which tested positive. Synthesis of our study and previous reports suggests that infection of P. persimilis with Wolbachia is extremely rare and of minor importance. We discuss the significance of our findings for future studies on the presence of Wolbachia in predaceous arthropods.     

Forensic DNA confirms intraguild killing of a chuditch (<Emphasis Type="Italic">Dasyurus geoffroii</Emphasis>) by a feral cat (<Emphasis Type="Italic">Felis catus</Emphasis>)

Because animals killed by predators are often found partially consumed or decomposed, identification of the predator is often unachievable by post mortem examination. Forensic DNA offers an alternative in such situations. Using a novel method to analyse DNA from bite wounds on a freshly-killed chuditch Dasyurus geoffroii, we describe the first confirmed instance in this species of intraguild killing by a feral cat. Unlike post mortem examination, our method of DNA melt curve analysis is highly accurate and requires less time and expense than DNA sequencing.     

Physiological aspects of tolerance in <Emphasis Type="Italic">Atriplex</Emphasis><Emphasis Type="Italic">halimus</Emphasis> L. to NaCl and drought

Forty-day-old seedlings of Atriplex halimus were treated either with NaCl (50, 300 and 550 mM) for the subsequent 30 days or with 15% PEG for the subsequent 10 days. As much as 50 mM of NaCl significantly increased shoot fresh and dry weight and height; nevertheless, 300 or 550 mM NaCl seemed to have no effect. On the other hand, these growth parameters were not affected by drought after 3 or 6 days, but were reduced after 10 days. The gas exchange parameters (photosynthetic rate, stomatal conductance and transpiration rate) were increased by 50 mM NaCl, but decreased by 300 and 550 mM. These parameters were decreased in response to drought only after 10 days of withholding water. In contrast to Na⁺, K⁺ was significantly decreased by NaCl but not by drought. The time course effect revealed that phosphoenol pyruvate carboxylase (PEPC) protein was doubled in response to NaCl after 1 and 5 h and continued thereafter, higher than control, while drought had no significant effect. Rubisco seemed unchanged by NaCl or drought. It could be concluded that the decrease in fresh weight might be attributed to the decrease in water content. Moreover, the decrease in photosynthesis could result from a decrease in stomatal conductance, a protective mechanism against water loss to improve water use efficiency. These findings indicate that Atriplex halimus tolerates NaCl and drought through decreasing growth, reducing gas exchange parameters to improve water use efficiency, uptake Na⁺ and saving, if any, the photosynthetic enzyme particularly PEPC.     

Peat-Based Inoculum of <Emphasis Type="Italic">Bradyrhizobium japonicum</Emphasis> and <Emphasis Type="Italic">Sinorhizobium fredii</Emphasis> Supplemented with Xanthan Gum

The addition of xanthan to high water retention capacity peat (HWRC) inoculants did not show differences on the survival of Bradyrhizobium japonicum E109. In low water retention capacity peats (LWRC) however, xanthan increased the survival of B.japonicum significantly. Xanthan showed the best effect at 0.1 g/l for B. japonicum, in contrast to Sinorhizobium fredii USDA205 where the concentrations evaluated (0–1.0 g/l) did not affected significantly its survival. Nevertheless, when the symbiotic performance on soybean was evaluated, the presence of 0.1 g xanthan/l increased the nodule number for both strains.     

High-efficiency cryopreservation of the medicinal orchid <Emphasis Type="Italic">Dendrobium nobile</Emphasis> Lindl.

An efficient protocol for cryopreservation of protocorm like bodies (PLBs) of Dendrobium nobile, based on encapsulation–dehydration (ED) and encapsulation–vitrification (EV), was established. In both cryogenic procedures, PLBs were initially osmoprotected with a mixture of 0.4 M sucrose and 2 M glycerol, incorporated in the encapsulation matrix [comprising 3% (w/v) sodium alginate and 0.1 M CaCl₂]. Out of the two methods, EV resulted in higher survival (78.1%) and regrowth (75.9%) than ED (53.3 and 50.2% respectively). Incorporation of 0.4 M sucrose and 2 M glycerol in the encapsulation matrix resulted in higher survival percentage after cryopreservation. In both the cases (ED and EV), shoots regenerated from cryopreserved PLBs with an intermediary PLB formation. Regenerated shoots were successfully rooted in the medium containing 1.5 mg/l Indole-3 butyric acid. Successful acclimatization of plantlets was obtained in the compost containing brick pieces and charcoal chunks (1:1) + a top layer of moss with a maximum survivability (82%). EV method proved to be most appropriate way to cryopreserve the PLBs of D. nobile. Regenerated plantlets showed normal morphology as that of control plants.     

Factors affecting the establishment of <Emphasis Type="Italic">Schoenoplectus</Emphasis><Emphasis Type="Italic">tabernaemontani</Emphasis> (C.C. Gmel.) Palla in urban lakeshore restorations

Despite their central role in lakeshore restoration, most littoral wetland plantings fail. The reasons for these failures are poorly understood, in part due to limited information on the effects of planting time, water depth, and propagation on the survival of emergent macrophyte plantings. We planted pots and prevegetated mats of softstem bulrush (Schoenoplectus tabernaemontani (C.C. Gmel.) Palla) at two different water depths (0–30 and 31–60 cm) in five lakes each month between May and September 2006 to evaluate the effects of planting month, water depth, and transplant type on the survival of planted S. tabernaemontani. Overall survival decreased from 73% at 30 days after planting to 40% pre-winter to 15% post-winter. The timing of planting was the most important factor influencing bulrush survival. Survival of bulrush planted later in the growing season is poor, regardless of the transplant type used, and should be avoided. During the optimal planting season of early-to-mid summer, transplants from pots are more likely to outperform mats, despite lower pre-planting biomass. Water depth is only important immediately after planting, after which time, its influence on successful establishment diminishes. Overall, our research indicated that key choices made by the practitioner can improve the likelihood that transplants establish in littoral wetland restorations.     

Reproduction and dispersal of wing-clipped predatory stinkbugs, <Emphasis Type="Italic">Podisus nigrispinus</Emphasis> in cotton fields

Release of arthropod predators holds promise for suppressing herbivorous insect populations in commercial crops below economic threshold levels, but dispersal from release sites remains a practical issue that can limit their impact. This study examined mating behavior, survival, reproduction, and dispersion of membranous wing-clipped and wing-intact adults of the predatory stinkbug Podisus nigrispinus (Dallas) (Hemiptera: Pentatomidae), a generalist predator of cotton pests in South America. After laboratory studies demonstrated that wing-clipping did not alter mating behavior or reproductive output, field studies were conducted in experimental plots. In each experiment, 50 mated females (5–10 days old) were released at a central point. After 24, 48, 72, and 96 h, dispersion was measured via drop-cloth samples at distances up to 16 m from the release point. After 96 h, plants on each survey and release point were collected and, in the laboratory, they were inspected for egg masses. During the first 24 to 48 h after release, predators from both groups disappeared, but recovery of the wing-clipped predators was significantly greater (38.6% for wing-clipped and 17.3% for wing-intact predators) in all three releases. Importantly, oviposition rates on the release site were about three times greater for wing-clipped females (0.07 vs. 0.02 egg masses per plant), indicating that limiting flight induces females to stay and lay their eggs, hence, allowing local establishment of a new generation of predators. This research is part of a larger project looking for improvement of natural predators into sustainable pest management conducted by the biological control and insect ecology laboratory (lead by Jorge B. Torres) of the “Universidade Federal Rural de Pernambuco (UFRPE) at Recife, PE, Brazil. Handling Editor: Patrick De Clercq     

The changes in the predatory behavior of the microturbellarian <Emphasis Type="Italic">Stenostomum sphagnetorum</Emphasis> on two species of toxin-secreting ciliates of the genus <Emphasis Type="Italic">Spirostomum</Emphasis>

It is known that the microturbellarian Stenostomum sphagnetorum, a common ciliate predator, is very sensitive against different types of toxins produced by other ciliates for chemical defense, and consequently, it is not able to capture and ingests these ciliates. In particular, when the predator tries to attack one of these toxin-secreting ciliates, it is forced to regurgitate the captured prey in response to the toxin discharged from the ciliates. In this study it is shown that after repeated attacks by S. sphagnetorum against two species of toxic ciliates (Spirostomum ambiguum and Spirostomum teres), the predator acquires a behavior of prey selection that leads to the exclusion of these ciliates among the possible prey and to the distinction between edible and inedible (toxic) ciliates. This learned behavior, which is maintained for days, is lost only after the asexual reproduction of the microturbellarian. In addition, S. sphagnetorum learns to recognize and avoid specimens of S. ambiguum and S. teres artificially deprived of their toxins, strongly suggesting that the toxins are not exclusively associated in the prey recognition of the microturbellarian.     

Examination of boldness traits in sexual and asexual mollies (<Emphasis Type="Italic">Poecilia latipinna</Emphasis>, <Emphasis Type="Italic">P. formosa</Emphasis>)

Considering the high costs of sexual reproduction (e.g., the production of males), its maintenance and predominance throughout the Animal Kingdom remain elusive. Especially the mechanisms allowing for a stable coexistence of closely related sexual and asexual species are still subject to a lively debate. Asexuals should rapidly outnumber sexuals due to higher population growth rates, unless they face some disadvantages. Here, we investigate potential differences in feeding behavior in a system of sexual (sailfin mollies, Poecilia latipinna) and coexisting gynogenetic fishes (Amazon mollies, Poecilia formosa). In two different experiments, we tested for differences in behavioral traits associated with boldness. Bold individuals take higher risks for gains in resources, so shyer individuals should be less competitive. Our study was motivated by the recent finding that P. formosa are less likely to be preyed upon by piscine predators than P. latipinna. We asked whether this result is indicative of low boldness in P. formosa. However, no differences between the two species were detectible in our behavioral experiments measuring (a) time to emerge from shelter to explore a novel environment, (b) latency time until feeding in a novel environment, and (c) recovery time until feeding restarted after a simulated predator attack. Furthermore, different boldness measures were not correlated with each other within individuals.     

Purification and biochemical properties of a glucose-stimulated β-D-glucosidase produced by <Emphasis Type="Italic">Humicola grisea</Emphasis> var. <Emphasis Type="Italic">thermoidea</Emphasis> grown on sugarcane bagasse

The effect of several carbon sources on the production of mycelial-bound β-glucosidase by Humicola grisea var. thermoidea in submerged fermentation was investigated. Maximum production occurred when cellulose was present in the culture medium, but higher specific activities were achieved with cellobiose or sugarcane bagasse. Xylose or glucose (1%) in the reaction medium stimulated β-glucosidase activity by about 2-fold in crude extracts from mycelia grown in sugarcane bagasse. The enzyme was purified by ammonium sulfate precipitation, followed by Sephadex G-200 and DEAE-cellulose chromatography, showing a single band in PAGE and SDS-PAGE. The β-glucosidase had a carbohydrate content of 43% and showed apparent molecular masses of 57 and 60 kDa, as estimated by SDS-PAGE and gel filtration, respectively. The optimal pH and temperature were 6.0 and 50°C, respectively. The purified enzyme was thermostable up to 60 min in water at 55°C and showed half-lives of 7 and 14 min when incubated in the absence or presence of 50 mM glucose, respectively, at 60°C. The enzyme hydrolyzed p-nitrophenyl-β-D-glucopyranoside, p-nitrophenyl-β-Dgalactopyranoside, p-nitrophenyl-β-D-fucopyranoside, p-nitrophenyl-β-D-xylopyranoside, o-nitrophenyl-β-Dgalactopyranoside, lactose, and cellobiose. The best synthetic and natural substrates were p-nitrophenyl-β-Dfucopyranoside and cellobiose, respectively. Purified enzyme activity was stimulated up to 2-fold by glucose or xylose at concentrations from 25 to 200 mM. The addition of purified or crude β-glucosidase to a reaction medium containing Trichoderma reesei cellulases increased the saccharification of sugarcane bagasse by about 50%. These findings suggest that H. grisea var. thermoidea β-glucosidase has a potential for biotechnological applications in the bioconversion of lignocellulosic materials.     

Relationship between glucose catabolism and xanthan production in <Emphasis Type="Italic">Xanthomonas oryzae</Emphasis> pv. <Emphasis Type="Italic">oryzae</Emphasis>

Two genes involved in central carbon metabolism were inactivated to modulate intracellular glucose 6-phosphate and to evaluate its effects on xanthan production in wild-type Xanthomonas oryzae pv. oryzae. Upon the inactivation of the phosphogluconate dehydratase gene (edd), intracellular glucose 6-phosphate increased from 0.05 to 1.17 mmol/g (dry cell wt). This was accompanied by increased xanthan production of up to 2.55 g/l (culture medium). In contrast, inactivation of 6-phosphogluconate dehydrogenase gene (gndA) did not influence intracellular glucose 6-phosphate nor xanthan production. The intracellular availability of glucose 6-phosphate is proposed as a rate-limiting factor in xanthan production, and it may be possible to increases production of xanthan by modulating the activities of enzymes in central carbon metabolism.     

Modulation of Carbohydrate Metabolism During <Emphasis Type="Italic">N</Emphasis>-Methyl <Emphasis Type="Italic">N</Emphasis>-Nitrosourea Induced Neurotoxicity in Mice: Role of Curcumin

The present study was carried out to elucidate the effectiveness of curcumin in mitigating the adverse effects caused by N-Methyl N-Nitrosourea (MNU) on mouse cerebellum and cerebrum. Male laca mice received either intravenous MNU treatment at a dose of 10 mg/kg bw in sterile double distilled water, curcumin alone 60 mg/kg bw in drinking water, or combined MNU and curcumin treatment on alternate days for a period of 2 months. The effects of different treatments were studied on carbohydrate metabolizing enzymes viz: hexokinase, glucose-6-phosphatase (G6P), glucose-6-isomerase (G6I), lactate dehydrogenase (LDH), succinate dehydrogenase (SDH) and glycogen levels. Curcumin supplementation to MNU treated mice was able to reduce significantly the activities of the G6P, G6I, hexokinase, LDH, SDH and increased the glycogen contents in both the regions of brain which were altered following MNU treatment. Hence, curcumin shall prove to be effective in ameliorating the adverse effects caused by MNU.