Light germination ofAnthoceros miyabeanus spores

The effects of light on the spore germination of a hornwort species,Anthoceros miyabeanus Steph., were investigated. Spores of this species were photoblastic, but their sensitivities to light quality were different. Under either continuous white, red or diffused daylight, more than 80% of the spores germinated, but under blue light none or a few of them germinated. Under continuous far-red light or in total darkness, the spores did not germinate at all.Anthoceros spores required red light irradiation for a very long duration, i.e., over 12–24 hr of red light for saturated germination. However, the spore germination showed clear photo-reversibility by repeated irradiation of red and far-red light. The germination pattern clearly varied with the light quality. There were two fundamental patterns; (1) cell mass type in white or blue light: spores divide before germination, and the sporelings divide frequently and form 1–2 rhizoids soon after germination, and (2) germ tube type in red light: spores germinate without cell division, and the single-cell sporelings elongate without cell division and rhizoid formation.     

Susceptibility of Larvae of Galleria mellonella to Infection by Aspergillus fumigatus is Dependent upon Stage of Conidial Germination

The ability of conidia of the human pathogenic fungus Aspergillus fumigatus to kill larvae of the insect Galleria mellonella was investigated. Conidia at different stages of the germination process displayed variations in their virulence as measured using the Galleria infection model. Non-germinating (‘resting’) conidia were avirulent except when an inoculation density of 1 × 10⁷ conidia per insect was used. Conidia that had been induced to commence the germination process by pre-culturing in growth medium for 3 h were capable of killing larvae at densities of 1 × 10⁶ and 1 × 10⁷ per insect. An inoculation density of 1 × 10⁵ conidia per insect remained avirulent. Conidia in the outgrowth phase of germination (characterised as the formation of a germ tube) were the most virulent and were capable of killing 100% of larvae after 5 or 24 h when 1 × 10⁷ or 1 × 10⁶ conidia, that had been allowed to germinate for 24 h, were used. Examination of the response of insect haemocytes to conidia at different stages of the germination process established that haemocytes could engulf non-germinating conidia and those in the early stages of the germination process but that conidia, which had reached the outgrowth stages of germination were not phagocytosed. The results presented here indicate that haemocytes of G. mellonella are capable of phagocytosing A. fumigatus conidia less than 3.0 μm in diameter but that conidia greater than this are too large to be engulfed. The virulence of A. fumigatus in G. mellonella larvae can be ascertained within 60–90 h if infection densities of 1 × 10⁶ or 1 × 10⁷ activated conidia (pre-incubated for 2–3 h) per insect are employed.     

First record on epizootics of Entomophthora grylli on grasshopper in Indian subcontinent: pathogen city and bio control potential on Oxya velox

A naturally-occurring fungus called Entomophthora grylli was for the first time isolated from two species of grasshopper Oxya velox and Oxya vicinia in Jammu and Kashmir, India. The epizootic was confined along Indo–Pak border between 74 degrees 24′ and 75 degrees 18′, East longitude and 32 degrees 50′ and 33 degrees 30′ North latitude. The fungus proved to be highly pathogenic and the natural mortality was significantly influenced by the population density which increased from 26.00 to 73.60 over the period of epizootics. On the basis of the available literature this appears to be the first record from the Indian sub-continent. While many infected grasshoppers apparently produced neither conidia nor resting spores, the cadavers were found to be full of hyphal bodies and resting spores towards the end of epizootics. These resting spores or their germ tubes were not invasive as such but if provided a saturated environment for a week, they start germinating, resulting in germ conidia which were able to induce dermal pathogencity. Further, it was observed that the disease could not be transmitted to healthy individuals by ingestion. However, the intra-haemocoel infectivity of fresh resting spores, germinated resting spores, and germ conidia proved to be highly pathogenic as they resulted in 81.4% grasshopper mortality. Although E. grylli is fastidious, it is possible to multiply it on a large scale as protoplasts which are infective upon injection in their hosts. However, the lack of a cell wall renders them very fragile, and they are neither infective upon application to the insect's cuticle nor upon ingestion. In the present study, a method on delivery of pathogen through “sticky molasses pan trap” was developed for inducing infection in grasshoppers in a paddy nursery which would facilitate its use as a bioinsecticide, analogous to other entomopathogenic fungi.     

The culture ofEntomophthora muscae (C) Fres. in carrot flies (Psila rosae F.) and the effect of temperature on the pathology of the fungus

A method for maintaining anin vivo culture ofEntomophthora muscae (C) Fres. on its original host, adult carrot flies (Psila rosae F.), is described. The lethal time for adult carrot flies was greatly influenced by temperature, both for infected and for uninfected flies. In the range 8.2°C–20.2°C the LT₅₀ for infected flies was about 5.4 times shorter than the estimated average life-span for uninfected flies. The discharge of primary spores was also strongly dependent on temperature. The total number of primary spores discharged per fly at 100% RH and in darkness ranged between 1.2×10⁴ and 9.6×10⁴ with a mean of 5.1×10⁴.      

Effect of relative humidity and origin of isolates of Neozygites tanajoae (Zygomycetes: Entomophthorales) on production of conidia from cassava green mite, Mononychellus tanajoa (Acari: Tetranychidae), cadavers

Neozygites tanajoae is a very specialized fungus pathogenic to the cassava green mite (CGM), Mononychellus tanajoa, an important cassava pest introduced to Africa from the Neotropics. Conidial discharge from cadavers of CGM that died from infections with 14 isolates of N. tanajoae collected from diverse climates of Brazil was quantified to help select potential candidate strains for introduction to Africa. Studies aimed to identify isolates with lower requirements for relative humidity for sporulation and isolates that discharged more conidia during short periods of moisture. At 96 ± 0.5% RH, production of conidia was variable and even isolates from the Brazilian semi-arid region, e.g., Petrolina and Itaberaba, produced few conidia. Significant differences in the numbers of conidia produced by diverse Brazilian isolates were observed after 6, 9 and 12 h at 100% RH. At 100% RH, production of primary conidia increased considerably from an average of 57 ± 4 conidia at 6 h to 509 ± 37 conidia at 12 h. The isolate sporulating least (BIN21) discharged only 45.7% of the number of conidia produced by isolate BIN1, one of the isolates producing the most spores. Results from this study demonstrate that differences in production of conidia among isolates should be considered when selecting Neozygites isolates for new biological control introductions.     

Humid incubation period and plantlet age influence acclimatization and establishment of micropropagated grapes

Summary In vitro rooted grape (Vitis vinifera L.) plantlets (4 or 8 wk from culturing microcuttings) were plantedex vitro in polythene sachets (24×12 cm) filled to one-third their height with planting mixture. The sachets were misted, closed, and incubated at ambient temperature (25–30°C) under 16 h photoperiod (40–50 μ E·m^−2.·sec⁻¹) for 1,2, or 3 wk before opening. Maximum establishment with no or minimum damage toin vitro formed leaves was obtained with 3 wk of closed sachet incubation in both age groups. Opening the sachet at 2 wk from planting resulted in marginal scorching of lower leaves and some reduction in establishment and vigor. Opening at 1 wk led to severe leaf scorching and significant reduction in establisment particularly in 4-wk-oldin vitro plantlets while growth was more affected in 8-wk-old ones. Relative humidity ofin vitro culture vessel was 68–75% while closed sachets had RH values of 45–77% depending on length of incubation and ambient RH. Diurnal variation in RH of sachet in relation to ambient RH was the major factor that facilitated acclimatization rather than the overall fall in RH during the period of closed incubation. Satisfactory acclimatization of plantlets to withstand the open sachet RH (50–55%) by 3 wk and the ambient RH (30–40%) by 4 wk was achieved. Monitoring water loss from detached leaves of plantlets showed a significant reduction between the date of planting and Week 3, and again between Weeks 3 and 4. Comparison of growthin vitro andex vitro suggested that shifting toex vitro earlier was more beneficial. This observation was confirmed by transferring 3-, 4-, and 5-wk-old plantlets fromin vitro rooting medium toex vitro and recording the growth at 8 wk fromin vitro culturing when 3 wkin vitro plus 5 wkex vitro combination showed maximum vigor. The leftover stumps after subculturing of 1–4-mo.-old stock cultures could also be effectively used forex vitro establishment.     

Ripe pollen carbohydrate changes in Trachycarpus fortunei: the effect of relative humidity

Pollen of the palm Trachycarpus fortunei was kept at 25°C and relative humidities (RH) of 20, 55 and 98%. Changes in viability, water content and carbohydrates were measured over 2–17 days. Water content remained almost constant at 20 and 50% RH and increased dramatically at 98%. Pollen viability and germination rate remained almost constant over 14 days at 20% RH and decreased to about 2% after 7–9 days at 55% and to even less at 98% RH. Although the three experimental conditions were constant, qualitative and quantitative variations in pollen carbohydrates were recorded, even after pollen had lost its viability. The quantities of mono-, di- and polysaccharides varied with the period of pollen storage at the various RH. The greatest changes in glucose, fructose and sucrose content were recorded at 55 and 98% RH. At these relative humidities, maximum glucose and fructose content and minimum sucrose content occurred at maximum water content. Starch was not present in mature pollen but appeared and peaked after 7–9 days of pollen storage at 55 and 98%. Appearance of starch coincided with an increase in pectin content. PAS-positive cytoplasmic polysaccharides showed an increasing trend at 20% RH. A relation was found between pollen viability, water content and monosaccharide content. Pollen viability and germination capacity remained high at 20% RH for 14 days. At this relative humidity, pollen water, glucose and fructose contents remained almost constant, while sucrose reached its maximum value. The fluctuations of more complex carbohydrates (starch, pectins and PAS-positive cytoplasmic polysaccharides) were less easy to interpret. Changes observed under experimental conditions could simulate processes occurring in nature during pollen presentation and dispersal.     

Persistence of <Emphasis Type="Italic">Paranosema</Emphasis> (<Emphasis Type="Italic">Nosema</Emphasis>) <Emphasis Type="Italic">locustae</Emphasis> (Microsporidia: Nosematidae) among grasshopper (Orthoptera: Acrididae) populations in the Inner Mongolia Rangeland,China

Paranosema (Nosema) locustae Canning has persisted in grasshopper populations in the Inner Mongolia Rangeland since spore treatment was applied in 1993. In the treatment year, a 58.32–71.43% reduction of grasshoppers was recorded and 59.26–80.36% of surviving grasshoppers of various species were infected. In the years following application, prevalence of P. locustae varied from 13.65% to 60.71%, demonstrating that P. locustae remains in grasshopper populations for many years. Infection prevalence was more than 60.00% for Dasyhippus barbipes (F.-W.), Bryodema luctuosum luctuosoma (Stoll) and Angaracris barabensis (Pall.) in 1993 but was very variable, ranging from 20.00% to 60.71% over the subsequent nine years. Disease prevalence was 43.72–60.71% in 1993 and 1994 for Oedaleus asiaticus B.-Bienko and Myrmeleotettix palpalis (Zub.) but gradually declined to approximately 20%, where it remained. Persistence of P. locustae in grasshopper populations may be important in keeping densities below economic thresholds for a number of years after application. Handling Editor: Helen Roy.     

Selection of entomopathogenic fungi for use in combination with sub-lethal doses of imidacloprid: perspectives for the control of the leaf-cutting ant <Emphasis Type="Italic">Atta sexdens</Emphasis><Emphasis Type="Italic">rubropilosa</Emphasis> Forel (Hymenoptera: Formicidae)

In the first part of this study, four isolates of the fungus Beauveria bassiana (Bals.) Vuillemin (LPP1, LPP2, CG05 and CG24) and one isolate of Metarhizium anisopliae (Metsch.) Sorokin (CG46) were tested against adult foragers of Atta sexdens rubropilosa. Ants were allowed to walk on filter paper discs, inside Petri dishes, previously impregnated with 1 ml of a conidia suspension (2 × 10⁷ conidia ml⁻¹), maintained at 80% RH and 26°C for 24 h and subsequently, transferred to sterile Petri dishes, maintained at 23°C, 80% RH, 24 h dark. The mean values of LT₅₀ for LPP2, LPP1, CG46, CG24 and CG05 were 3.5, 3.7, 3.8, 4.2 and 4.4 days, respectively. Control insects for all tests in this study showed less than 10% mortality. Experiments were carried out to test the toxicity of imidacloprid (IMI) to A. sexdens rubropilosa. Mortality was evaluated 10 days following a 24 h exposure to the insecticide. Percent mortality caused by 500, 200, 100 and 10 ppm IMI was 77.8, 56.7, 45.5 and 5.5 respectively. Insects treated with 10 ppm IMI were observed to have reduced locomotor activity 24 h after exposure to the insecticide. The LC₅₀ of IMI was 154.3 ppm. Subsequent tests were carried out to evaluate the combination of a sub-lethal dose of IMI (10 ppm) and infection by CG24 (1 × 10⁷ conidia ml⁻¹). Mortality due to fungal infection alone was 43.3%. Mortality of insects treated with IMI followed by exposure to the fungus was 64.3%. These results indicate that IMI significantly increases the susceptibility of ants to infection by B. bassiana CG24.     

Conidial germination and germ tube elongation of Phomopsis amaranthicola and Microsphaeropsis amaranthi on leaf surfaces of seven Amaranthus species: Implications for biological control

Microsphaeropsis amaranthi and Phomopsis amaranthicola are potential biological control agents for several Amaranthus species. In an effort to understand the initial infection processes with these pathogens, a study was conducted of the conidial germination and germ tube length (μm) on the weed leaf surfaces at 21 °C and 28 °C. Weeds included Amaranthus rudis, A. palmeri, A. powellii, A. retroflexus, A. spinosus, A. hybridus, and A. albus. For P. amaranthicola, conidial germination and germ tube length varied among the seven weed species at both temperatures, while for M. amaranthi the differences in germ tube lengths were significant among weed species only at 21 °C. While the conidia of M. amaranthi and P. amaranthicola germinated on the leaf surfaces of all seven weed species, temperature appeared to impact the number and length of germ tubes on the leaf surfaces. The percentage of germinated conidia and the length of germ tubes at both temperatures were often greater for M. amaranthi than for P. amaranthicola. In order for the fungal pathogen to successfully infect and kill a weedy host, conidia must germinate and form a germ tube, two processes that vary with host species and temperature for M. amaranthi and P. amaranthicola. The extent to which successive infection processes, e.g., penetration, invasion and colonization, contribute to host specificity warrants study.     

The survival ofZoophthora radicans (Zygomycetes: entomophthorales) isolates as hyphal bodies in mummified larvae ofPlutella xylostella (Lep.: Yponomeutidae)

The survival of three isolates ofZoophthora radicans (NW 250, NW 253 & NW 182) as hyphal bodies in dried larvae ofPlutella xylostella stored at 4, 10 and 20°C and 20% R.H was determined. After storage at 20°C, the production of conidia by all isolates was unaffected after 2 weeks but diminished increasingly after 4 and 8 weeks and was entirely lost after 16 weeks. By comparison conidium production at 10°C was unaffected after 16 weeks (isolates NW 250 and NW 182) and, 24 weeks (NW 253) of storage though it declined rapidly in all isolates thereafter. At 4°C many conidia were produced by all isolates even after 34 weeks of storage. These results are consistent with work on other entomophthoralean fungi in dried cadavers suggesting that this may be a common survival strategy in these fungi. NW 250, 253 and 182 were isolated fromP. xylostella in Malaysia and Taiwan, where conditions allow the host to remain active throughout the year. None produced resting sporesin vivo orin vitro but as hosts are always available the ability to survive short dry periods is probably more important than long-term survival for which resting spores are most adapted.      

Effect of Host Plant on the Potential ofPaecilomyces fumosoroseus(Deuteromycotina: Hyphomycetes) for Controlling the Silverleaf Whitefly,Bemisia argentifolii(Homoptera: Aleyrodidae) in Greenhouses

We determined host plant effect on susceptibility of the silverleaf whitefly,Bemisia argentifolii, to the entomopathogenic fungusPaecilomyces fumosoroseus. Whiteflies were reared on three vegetable species (cucumber, cabbage, and tomato) and three cultivars of tomato (Heatwave, Better Boy, and Rutgers). Second instars were sprayed with 5 × 10⁴conidia/cm²ofPfr97, aP. fumosoroseusstrain, used as a microbial control agent of whiteflies. Trials were conducted in an experimental greenhouse, where temperature and relative humidity were adjusted to favor infection (22–33°C, and 68–100% RH). Larval susceptibility to fungal infection was high and not significantly affected by the host plant. Mortality was > 70% 1 week after treatment and increased further during the second week. Percentages of cadavers with subsequent production of conidia observed in the greenhouse did not vary significantly either with the host vegetable species (85–93% 7 days after treatment and 99–100% 14 days after treatment), or with the cultivar of tomato (96–97% 7 days after treatment and 99–100% 14 days after treatment). After incubation under optimal laboratory conditions, the percentages based on the total number of sporulating cadavers (includingin situsporulating individuals and cadavers sporulating afterin vitroincubation) were not significantly influenced either by host vegetable or cultivar of tomato. According to the conditions prevailing in the series of experiments with the three vegetable species or in the series of experiments with the three cultivars of tomatoes, the production of newly formed conidia varied from approximately 10,000 to 18,000 conidia/cadaver. However, in both series, there was no significant influence of the host vegetable species or cultivar. The survival of the newly formed conidia harvested 7 days following treatment reached more than 50% but was not affected by host plant. These results indicate thatP. fumosoroseusshows potential as a microbial control agent for controllingB. argentifoliion greenhouse crops.     

Acid phosphatase activity in hemolymph of the migratory grasshopper,Melanoplus sanguinipes, duringBeauveria bassiana infection

The distribution and abundance of acid phosphatase (AP) in hemolymph (HL), plasma (PM) and hemocyte lysate supernatant (HLS) of the migratory grasshopper,Melanoplus sanguinipes infected withBeauveria bassiana (strain GK 2016) has been examined. AP activity was determined at intervals from 30 min to 60 h postinjection of 2 μl of 1×10⁸ conidia/ml per grasshopper. The enzyme was detected with the substrate β-glycerophosphate in sodium acetate acetic acid buffer form hemocytes (HC) and withp-nitrophenol phosphate sodium salt for HL, PM and HLS. In results of experiment 1 proportion of HC showing AP activity increased 1–2 h, then returned to normal after 4 h. However, inB. bassiana-injected grasshoppers, a second increase was noted 24 h later which was not seen in the Tween-80-injected insects. Uninjected controls showed no change with time in the proportion of HC with AP activity. Studies were also made of the distribution of AP activity in the HL, PM, and HLS. AP activity in HL appeared to vary with the sex of the grasshoppers. Females showed increase in AP activity in HL 18–24 h after injection withB. bassiana, whereas males only showed an increase 1 h after injection. Assay of HLS showed that the level of AP activity did not change significantly throughout the experiment. Changes in AP activity in PM, in bothB. bassiana — and Tween-80-injected insects (both sexes) paralleled those of the HL, indicating that the enzyme is released from the HC. The observations are discussed in terms of the possible role of AP in the immune response ofM. sanguinipes.     

Susceptibility of Brevipalpus phoenicis to entomopathogenic fungi

The pathogenicity of 52 isolates from several fungus species was studied for the false spider mite Brevipalpus phoenicis. In addition, the main stages during the course of infection by Hirsutella thompsonii, by far the most virulent pathogen, were studied by means of light and electron microscopy. Adult mites were confined to arenas prepared with citrus leaves in acrylic dishes containing agar–water. Conidial suspensions containing 10⁸ conidia/ml were applied, except for H. thompsonii, where a concentration of 10⁷ conidia/ml was used. The H. thompsonii isolates caused higher mortality, with indices higher than 90%. Observations under the scanning electron microscope (SEM) were performed at 0, 6, 12, 24, 48, 72, and 120 h after application of a H. thompsonii suspension containing 10⁷ conidia/ml. Twenty-four hours after inoculation, H. thompsonii conidia were observed attached to the mite’s integument. The conidia germinated and penetrated through the base of the setae on the hysterosoma. Colonization occurred after 48 h, as evidenced by mortality. Conidiogenesis occurred after 120 h, with the development of mycelium and conidiophores emerging from the posterior and anterior parts of the mite.     

Pathogenicity of Beauveria bassiana (Deuteromycotina: Hypomycetes) to Larvae of the Small Poplar Longhorn Beetle, Saperda populnea (Coleoptera: Cerambycidae)

The small poplar longhorn beetle, Saperda populnea is an important pest of Lombardy poplars (Populus nigra L.) in Turkey. A survey for natural entomopathogenic fungi of S. populnea larvae was made in Erzurum, Turkey, during the period 2004–2005. Larvae (13.5%) infected with a strain of the fungus Beauveria bassiana were found. The pathogenicity of B. bassiana strain 46 was conducted with different concentrations of conidia (10⁶, 10⁷ and 10⁸ conidia/ml) of this isolate on S. populnea larvae. The lowest concentration (10⁶ conidia/ml) caused about 56% mortality within 6 days. One hundred percent mortality was achieved after median lethal time (LT₅₀) of 4.6 and 4.4 days for 10⁷ and 10⁸ conidia/ml, respectively. There were no significant differences between median lethal times. This is the first record of natural infection of S. populnea larvae by B. bassiana.     

OBSERVATIONS ON THE SURVIVAL AND GERMINATION OF RESTING SPORES OF THREE CHAETOCEROS (BACILLARIOPHYCEAE) SPECIES1,2

Resting spores (hypnospores) of Chaetoceros diadema (Ehrenberg) Gran, Chaetoceros vanheurckii Gran, and Chaetoceros didymus Ehrenberg were collected from a large plastic enclosure moored in Saanich Inlet, B.C., Canada. The effects of combinations of temperature and irradiance on the germination of these resting spores were investigated. Nutrient uptake, carbon fixation, and changes in the photosynthetic capacity of the germinating spores were also examined. Resting spores germinated optimally at combinations of temperature and irradiance similar to those in the environment during sporulation. They did not germinate at irradiances 1.3 μEin m^?2 s^?1 or temperatures >25.3° C. Nitrate, phosphate and silicate were taken up after the resting spores had germinated and resumed vegetative growth. Chlorophyll a fluorescence in vivo, and the DCMU-induced increase in in vivo fluorescence also increased after the resting spores had germinated. Resting spores began to fix carbon as soon as they were placed in light. Spores remained viable for at least 645 d. The length of time between first exposure to light and germination did not change during this period; however, the percentage of viable resting spores decreased markedly. None of the Chaetoceros spores germinated after 737 d of storage at 2–4° C in darkness.     

Infectivity of two members of theEntomophthora muscae complex [Zygomycetes: Entomophthorales] forMusca domestica [Dipt.: Muscidae]

Dose-mortality studies were conducted with 2 members of theEntomophthora muscae (Cohn) Fresenius complex from southern California (CA) and Denmark (DA) infecting house flies,Musca domestica L., from southern California. Primary conidia of the DA form were significantly more infective (LC₅₀=34 conidia/mm²) than primary conidia of the CA form (LC₅₀=67 conidia/mm²) for 2–7 days old (‘young’) flies. Infectivity (single experimental trial) for 10–14 day old (‘old’) flies of primary conidia of the CA form (LC₅₀=34 conidia/mm²) was similar to that of the DA form for young flies. Secondary conidia of the CA form were markedly more infective (LC₅₀=0.36 conidia/mm²) than primary conidia of either form. Dose had no significant effect on incubation period for primary conidia of either form, but increased doses resulted in significantly shorter incubation periods for flies exposed to secondary conidia of the CA form.      

Improvement of English walnut somatic embryo germination and conversion by desiccation treatments and plantlet development by lower medium salts

Summary Well-developed somatic embryos were selected from a repetivively somatic embryo line derived from embryonic axes of immature zygotic embryos of English walnut ‘No. 120’ (Juglans regia L.) for germination and conversion studies. In germinating dishes, somatic embryos germinated into only shoots, only roots, or both shoots and roots. Without any pretreatment, 28% somatic embryos germinated, while those treated with 2.5–5.0 mg 1⁻¹ (7.2–14.4 μmol) gibberellic acid (GA₃) germinated at 25–28% and those receiving a cold treatment of 2–3 mo. at 3–4°C germinated at 30–43%. However, only 4–19% of the germinating embryos showed both shoots and roots. Treated with desiccation, either with CaCl₂·6H₂O or Ca(NO₃)₂·4H₂O at 20°C in the dark for 3 d, somatic embryos germinated at 85–91%, 57–69% of which had both shoots and roots. Treatment with 2 mo. cold storage in combination with desiccation using Ca(NO₃)₂·4H₂O resulted in 92% of somatic embryos germinating, 70% of which showed both shoots and roots. No significant differences were observed between solid and liquid germination media. After transferring the germinating embryos to plantlet development media, 52–63% of those with both shoots and roots developed into plantlets while 11% with only shoots or 9% with only roots converted into plantlets. Plantlet development was improved by using lower medium salts and sucrose concentrations. The addition of activated charcoal enhanced root development, particularly root branching. Of 131 plants transplanted, 91 plants were acclimatized to a greenhouse.     

Effect of fungal infection on reproductive potential and survival time of <Emphasis Type="Italic">Tetranychus urticae</Emphasis> (Acari: Tetranychidae)

The effect of fungal infection on the reproductive potential of two-spotted spider mite, Tetranychus urticae, was evaluated as part of the full biocontrol potential of three entomopathogenic fungi by modeling of fecundity probability. Female mites (≤2-day-old) on leaves were exposed to the sprays of Beauveria bassiana, Paecilomyces fumosoroseus and Metarhizium anisopliae at the concentrations of 1.13 × 10³, 1.55 × 10³ and 0.95 × 10³ deposited conidia mm⁻² and then individually reared at 25°C and 12:12 L:D for oviposition. Mite mortalities 10 days after spraying were 73.1, 75.4 and 67.9% in the fungal treatments versus 15.5% in control. On average, females infected by the three fungal species survived 5.8, 6.2 and 6.3 days, and laid 3.1, 4.0 and 4.0 eggs per capita, respectively. These were 3–4 fold lower than the control fecundity at 12.3. The cumulative probabilities [P(m ≤ N)] for the counts of infected and non-infected (control) females laying m eggs per capita (m ≤ N) during 10 days fit very well the equation P(m ≤ N) = 1/[1 + exp(a + bm)] (r ² ≥ 0.98), yielding a solution to the probability for the female mites to achieve a specific fecundity {P(m ≤ N)−P[m ≤ (N − 1)]}. Consequently, the infected mites had 71–78% chance to lay ≤5 eggs per capita but only 5–8% to deposit >10 eggs despite some variation among the tested fungi. In contrast, the chances for the non-infected mites to achieve the low and high fecundities were 23 and 55%. The fitted probabilities provide a full coverage of the fecundity potential of infected versus non-infected mites and are more informative than the mean fecundities.     

An energy budget for Simocephalus vetulus (O. F. Muller) (Crustacea : Cladocera)

We discuss the energetics of a cladoceran, Simocephalus vetulus at different temperatures (8.0 ± 1.0, 15.0 ± 1.0, 21.0 ± 1.0 and 28.0 ± 1.0 °C) and food (Chlamydomonas sp.) concentrations (25 × 10³, 50 × 10³, 75 × 10³ and 100 × 10³ cells ml⁻¹). Increase in temperature accelerated ingestion and, to some extent, oxygen consumption. The study revealed a high reproduction efficiency in S. vetulus. Net growth efficiency (ECI) was higher (13.17–41.18%) in pre-adults than in adults (2.71–8.40%). The assimilated energy (A) increased with increasing food concentration at all temperatures. Assimilation efficiency (AD) decreased with increasing food concentrations. The energy used for growth (P) was nearly constant at all food levels because the egested energy increased and assimilation efficiency decreased as food concentration increased.