Initial Inoculation Density Research Articles

A Novel Algal–Algal Microbial Fuel Cell for Enhanced Chemical Oxygen Demand Removal

To enhance the removal of COD (Chemical Oxygen Demand) by microalgae, this study constructed a novel microalgae–microalgae microbial fuel cell system (AA-MFC). It investigated the coupling relationship between the COD treatment efficiency at the anode and the production of high-value microalgal products at the cathode, as well as explored the effects of different initial inoculum densities and light–dark cycles. The experiment first measured the operational performance of the newly constructed AA-MFC in open-circuit and closed-circuit modes, demonstrating that this novel AA-MFC could start up rapidly within 32 h and operate stably. The results showed that the AA-MFC enhanced the removal of COD and the growth of microalgae biomass at the anode while maintaining stable power generation. When the initial inoculation density of the anode was 1.2 × 108 cell/cm2 and the light–dark cycle time was 18:6 h, the AA-MFC had the most obvious promoting effect on the COD removal of the anode. Compared with normal culture conditions, the COD removal rate increased by 26.0% to 96.1%. These results indicate that the AA-MFC can not only effectively remove pollutants, but also promote the accumulation of high-value microalgae biomass.

Effects on fatty acids, biochemical composition and growth of rotifer (Brachionus plicatilis) fed with different concentrations of Nannochloropsis sp.

The density of microalgae and nutrient content have impact on the population growth rate, egg rate and nutritional values of rotifers. The aim of this study was to investigate the effects of different concentrations of the alga Nannochloropsis sp. (N10: 10x106, N20: 20x106, N30: 30x106 cells mL-1) on the growth, egg rate, biochemical composition and fatty acid profile of the rotifer Brachionus plicatilis. To maintain a consistent algae density, an equivalent quantity was supplemented to compensate for any reduction. The study was started with three replicates, each with an initial inoculation density of 200 Brachionus individuals mL-1 . The investigation spanned 5 days, during which population parameters (total number of individuals, proportion of individuals with eggs and growth rate) were calculated. After the study period, rotifers were harvested for subsequent biochemical and fatty acid analyses. Notably, the N30 group showed the highest proportions of crude protein (54.41%) and crude lipid (34.5%). The N20 group displayed the most substantial content of total fatty acids, recording a value of 70.69%. Consequently, the N30 group, with a concentration of 30x106 cells mL-1, emerged as the most proficient group, demonstrating superior performance in both population growth and biochemical composition.

Determination of the Optimal Conditions for the Mass Culture of Large-Type Rotifers (Brachionus plicatilis) at Low Temperatures

We aimed to determine the optimal conditions for the mass culture of rotifers, which can be used as feed for cold-water fish species at low temperatures. The growth and specific growth rates (SGRs) of rotifers were assessed considering water temperature, salinity, density, dissolved oxygen (DO) levels, and the amount of Chlorella supplied as feed. The growth of rotifers was higher at 15 °C than at 10 °C and at salinities of ~11–17 psu. Initial inoculation densities of 500 and 700 individuals/mL resulted in the highest rotifer density, and SGR was highest at 100 individuals/mL. DO concentration did not significantly affect the growth and SGRs of rotifers. Enrichment with fatty acids is important to supplement the diet of cold-water fish species. Highly unsaturated fatty acid content increased with enrichment time to 14.04 ± 0.86% at 12 h and 15.58 ± 2.20% at 24 h. Thus, the optimal conditions for rotifer mass culture are a water temperature of 15 °C, salinity of 11–17 psu, initial inoculation density of 300–500 individuals/mL, DO concentration of 8 mg/L or more, and Chlorella supply at 7.5 × 1012 cells/mL. Therefore, the present study suggests optimal culture conditions of rotifers at low temperatures for breeding cold-water fish species.

Bioremediation of propylbenzenes by a novel marine microalga Rhinomonas reticulata S6A isolated from Daya Bay: acute toxicity, growth kinetics and biodegradation performance

This study investigated the degradation characteristics of propylbenzenes (PBZs, including isopropylbenzene and n-propylbenzene), with high leakage risks and ecological hazards, by a newly isolated marine microalga named Rhinomonas reticulata S6A which is a promising candidate for eco-friendly bioremediation from marine. About 72% and 56% of n-PBZ and i-PBZ can be degraded after 7 days in culture. The acute toxicity of n-PBZ (96h - EC50 = 2.38 mg/L) was higher than that of i-PBZ (96h - EC50 = 3.65 mg/L). The growth inhibition kinetics of this strain were consistent with the Edwards model (R2 = 0.998) and Aiba model (R2 = 0.999). The optimal concentrations for the degradation of n-PBZ and i-PBZ were calculated to be 2.42 mg/L and 2.78 mg/L, respectively. The degradation trends of PBZs conformed to the zero-order kinetic model, and k increased with initial concentrations. The moderate increase in inoculation density could accelerate the degradation of PBZs, with the maximum specific growth rates (r) of 1.116/d (n-PBZ) and 1.230/d (i-PBZ) at the initial inoculation density of 104 cells/mL, while over-inoculation (initial microalgae density more than 105 cells/mL) was not conducive to the degradation of the pollutants. There is not much data on the biodegradation of PBZs in the aquatic environment, so it would be worthwhile to try to apply the new microalgae to explore the fate of PBZs.

The proliferation rule of Microcystis aeruginosa under different initial pH conditions and its influence on the pH value of the environment

This study investigated the characteristics of the proliferation process of Microcystis aeruginosa and its changes to environmental pH values under different initial pH values and different initial inoculation densities. The results showed that although the initial pH value or the initial inoculation density was different, the pH values of the culture systems fluctuated up and down throughout the proliferation of M. aeruginosa, both on a daily and hourly time scale, and then tended to stabilize around the same value of 10.0 at the end of proliferation. The optimal pH value for the proliferation of M. aeruginosa was 9.55. This study creatively proposes that the period when the environmental pH value starts to rise rapidly toward 9.0 could be selected as an early warning period for a cyanobacterial outbreak, and the environmental pH value could be adjusted to below 8.0 to delay the outbreak. These results provide a scientific basis for further understanding the mechanism of cyanobacterial blooms and formulating pH-based control strategies.

The effect of volatile fatty acids on the growth and lipid properties of two microalgae strains during batch heterotrophic cultivation

To overcome the bottlenecks of waste resource utilization and energy shortage that restrict the commercial production of microalgae biodiesel, volatile fatty acids (VFAs) derived from activated sludge were used as the sole carbon source to culture oleaginous microalgae Chlorella pyrenoidosa FACHB-1216 and Scenedesmus quadricauda FACHB-1297 under the mixotrophic and heterotrophic cultivation. Four VFAs ratios (acetic acids (AA): propionic acids (PA): butyric acids (BA)) were tested to determine the effects and mechanisms of the VFAs on the two microalgae. The highest lipid content (29.54%) and lipid production (71.10 mg L−1) were achieved by S. quadricauda at the VFAs ratio of 6: 1: 3 under heterotrophic condition, with 46.27% and 67.52% removal efficiencies of total nitrogen and phosphorus, respectively. The assimilation efficiency of AA was the highest at 73.37%, followed by that of PA and BA. For C. pyrenoidosa, VFAs promoted the rapid reproduction within 2 days under the heterotrophic condition at different initial inoculation densities. At the optimal VFA ratio, algae achieved the highest biomass concentration (0.14 ± 0.02 g L−1), with a specific growth rate of 0.91 d−1 and biomass productivity of 125.17 mg L−1 d−1. The removal rates of total nitrogen and phosphorus were 47.03% and 74.40%, respectively, and the assimilation efficiency of AA was the best (61.06%). High AA assimilation efficiency under the heterotrophic condition was beneficial for the algal growth and lipid accumulation. These results simultaneously produced microalgae-based bioenergy and recycled VFAs in anaerobically digested effluent.

A quantitative method to assess bacterial adhesion using recombinant bioluminescent Pseudomonas aeruginosa.

Bioluminescence technology has been widely used in the field of medical detection. The bioluminescent lux reporter system provides a non-invasive platform to monitor bacterial growth and expression in real time. This study aimed to establish a method for detecting bacterial adhesion on the surface of materials, including medical devices, by using recombinant bioluminescent Pseudomonas aeruginosa containing a lux reporter. By monitoring the growth and bioluminescent properties of the recombinant PAO1-lux strain, the optimal test conditions for bacterial adhesion detection in vitro were determined to be as follows: an initial inoculation density of 105 to 106 CFU/mL, M9 medium at a pH 6.2, an adhesion time of 6 h, and the collection of adherent bacteria by ultrasonic cleaning. The traditional CFU counting method and the bioluminescence method were compared, and the applicability of the new method was verified by testing the adhesion of bacteria on the surface of various materials. The validated bioluminescent strains could serve as strong candidates to be used as bacterial detection tools in applications such as bacterial adhesion evaluation as well as supplements and alternatives to traditional microbiological testing procedures. In addition, this method has the potential to enable the study of bacterial adhesion on the surface of inanimate objects and living tissues. With the development of this method and its wide applicability, it is expected to become a standard method for the detection of bacterial adhesion and the screening of anti-adhesion materials.

Competition betweenBrachionus calyciflorusandBrachionus angularis(Rotifera) in relation to algal food level and initial population density

Intensive interspecific competition for limited resource often can result in the exclusion of inferior competitors, decrease the species diversity and alter the structure of the zooplankton community. Competitive experiments betweenBrachionus calyciflorusandBrachionus angulariswere conducted at threeScenedesmusdensities (0.5 × 106, 1.0 × 106and 2.0 × 106cells ml−1) and four initial inoculation densities (numerically, 100%B. calyciflorus, 75%B. calyciflorusand 25%B. angularis, 50% each of the two species, 25%B. calyciflorusand 75%B. angularis, and 100%B. angularis). The results showed that at the low food level,B. angularisoutcompetedB. calyciflorusandvice versaat the high food levels. At the intermediate food level,B. angulariswas displaced byB. calyciflorusat nearly all the initial inoculation densities except for 75%B. angularis,at which both species coexisted until the termination of the experiment. When grown alone at 0.5 × 106, 1.0 × 106and 2.0 × 106cells ml−1ofScenedesmus,B. calyciflorusreached the peak abundance values of 34 ± 4, 69 ± 5 and 101 ± 9 individuals ml−1and had population growth rates of 0.608 ± 0.032, 0.654 ± 0.033 and 0.518 ± 0.039 d−1, respectively. The corresponding values forB. angulariswere 265 ± 8, 330 ± 30 and 802 ± 87 individuals ml−1and 0.623 ± 0.020, 0.770 ± 0.036 and 0.871 ± 0.013 d−1. The results suggest that the outcome of competition depends not only on the size of the competing species and food availability but also on their colonizing density.

Effects of seed age, inoculum density, and culture conditions on growth and hydrocarbon accumulation of Botryococcus braunii SAG807-1 with attached culture

BackgroundBotryococcus braunii is difficult to cultivate and has a limited amount of substantive scale-up and productivity assessments with conventionally suspended cultivation systems, such as open pond or closed photobioreactors. The biomass concentrations of cultivated microalgal biofilms are much higher than those of suspension cultures, and the attached microalgal cells are easily separated from cultivation media. However, studies on the attached cultivation conditions for B. braunii have been rarely performed.ResultsHerein, an attached cultivation method for B. braunii SAG 807-1 incubation was introduced. The effects of primary culture conditions on growth and hydrocarbon accumulation were investigated. Seed age influenced the biomass and hydrocarbon accumulation in B. braunii, and the highest values were 5.97 and 2.99 g m−2 day−1, respectively, when seed age was 14 days. The appropriate range of initial inoculation density was 7.9–10.1 g m−2. Light intensity was a dominating factor influencing B. braunii’s growth in the attached culture, and the light saturation point was 100–150 μmol m−2 s−1. Periodic illumination in 8:16 light: dark cycle had the highest utilisation of photons at approximately 1.0 g of biomass per mole of photons. The increasing CO2 concentration in aerated gas improved the growth rate, but its concentration should be 1%.ConclusionsAttached algal cultivation systems have been widely explored. However, the optimised values for aqueous suspension methods may be unnecessary for the attached system. Optimised seed age, inoculum density, CO2 concentration, light intensity and photoperiod can improve the growth and hydrocarbon accumulation of B. braunii SAG807-1 with the attached culture.

Effects of temperature and initial inoculation density on root-knot nematode (<I>Meloidogyne incognita</I>) infection ability

在棚室盆栽条件下, 研究了南方根结线虫在不同温度、不同蔬菜寄主及不同初始接种密度下的症状表现。结果表明, 5—9月, 气温在22.17~27.61 ℃之间, 南方根结线虫在黄瓜上最短 3 d出现明显症状; 1—4月和10—12月, 气温在15.38~18.67 ℃之间, 15 d出现明显症状, 显症时间延迟, 发病程度受到抑制。15种感病蔬菜寄主中, 以西瓜、甜瓜、苦瓜、黄瓜、南瓜、西葫芦和小青菜症状表现时间比较短, 10 d以内表现症状; 番茄、豇豆、茄子和甘蓝症状表现时间比较长, 15 d出现症状; 而韭菜和葱30 d仍未出现明显症状。南方根结线虫对6种蔬菜(黄瓜、番茄、茄子、小青菜、辣椒、韭菜)的侵染能力存在显著差异, 黄瓜和番茄的根结百分率、根际二龄幼虫数、雌成虫数和卵块数显著高于茄子、小青菜、辣椒和韭菜。随着二龄幼虫接种密度的增加, 番茄感病症状表现时间缩短, 相应的病情指数也在增加, 在接种量为80头·100g^-1(土)时, 4 d出现明显症状。接种量为160头·100g^-1(土)时超过其饱和数量, 发病率和病情指数增加不明显。?

Experimental study of the interspecific competition between two sibling marine herbivorous rotifers in relation to food availability and initial population density

Our laboratory study concerns the competitive interaction between two marine rotifer species Brachionus plicatilis and Brachionus rotundiformis at five algal (Nannochloropsis salina) concentrations (0.4×106 to 32.4×106 cells/ml) and at four initial inoculation densities (numerically, 100% B. plicatilis; 75% B. plicatilis and 25% B. rotundiformis, 50% each of the two species; 25% B. plicatilis and 75% B. rotundiformis and 100% B. rotundiformis. The initial biomass varied as 0.33 and 0.22 µg/ml for B. plicatilis and B. rotundiformis respectively. Experiments were performed at (25±1)°C. Population densities were enumerated and the medium was changed daily up to 8 d in the experiment. At the lowest food level tested, B. rotundiformis formed superior competitor than B. plicatilis, regardless of starting inoculation density. Generally when the food concentrations increased, B. plicatilis showed a greater increase in biomass than B. rotundiformis. B. rotundiformis formed the largest in population growth, regardless of increasing food concentrations. When grown alone, B. plicatilis reached peak abundances of (1.311 5±0.028) and (137.5±0.014) µg/ml at low and high food densities respectively. The corresponding values of B. rotundiformis were 0.724 5±0.016 and 18.15±0.021. The adverse effects of B. rotundiformis on the peak abundances of B. plicatilis were observed at the lowest food level and higher initial density. The rate of population growth in controls varied from (0.792±0.162) to (1.482±0.132) µm/d for B. plicatilis and (0.445±0.041) to (0.856±0.012) µm/d for B. rotundiformis, depending on food level. When both species were introduced together, low food levels favoured higher abundance of B. rotundiformis than B. plicatilis, suggesting that increased population density of the smaller B. rotundiformis was more successfull than larger B. plicatilis in brackish waters. Our work reveals that available food (type and quantity) along with starting inoculation density had significant effect on the interspecific competition between marine sibling rotifer species in zooplankton community structure.

Study on Biological Fixation of High-Concentration CO<sub>2</sub> Using Chlorella Pyrenoidosa

CO2 emissions have serious impact on the world economy, especially at high-concentration. Green algae are known to have a tolerance to high CO2 level. In this paper, the rate of CO2 fixation using Chlorella Pyrenoidosa was analyzed in different environments. 1) Chlorella Pyrenoidosa fixed CO2 slowly in air, while this alga could rapidly grow in high-concentration CO2 until CO2 level was beyond 10%. At 25% CO2, the rate of CO2 fixation was lower than that at 10% CO2, but still 1.18 times as higher as in air. 2) At lower initial inoculation density of Chlorella Pyrenoidosa, its growth rate was relatively high but the rate of CO2 fixation was low. When initial inoculation density beyond 0.187×108cells/ml, the average rate of CO2 fixation was ranged from 2.786 gCO2/L·d to 2.847 gCO2/L·d. 3) During the five days, the average rate of CO2 fixation was 3.044 gCO2/L·d in NaNO3 resource. When NH4Cl or NaNO2 is regarded as N resource, the rate of CO2 fixation was almost neglectable.

Collective escape of chemotactic swimmers through microscopic ratchets.

We report on the emergence of spontaneously forming migrating bands of E. coli bacteria inside a microchannel containing microstructured ratchets. We show that a collection of bacteria is able to migrate against the funnel-shaped barriers by creating and maintaining a chemoattractant gradient. A transition between pure rectification and chemotaxis-driven collective motion is predicted from theoretical models, and is observed experimentally as the initial inoculation density is varied.

Effects of initial inoculation density of Paenibacillus polymyxa on colony formation and starch‐hydrolytic activity in relation to root rot in ginseng

To examine the relationships between population growth and biological characters of the plant-growth-promoting rhizobacterium Paenibacillus polymyxa GBR-1. Population growth, colony formation, starch-hydrolytic activity, and ginseng root rot caused by P. polymyxa GBR-1 isolated from a rotten ginseng root were examined in vitro and in vivo at high [1 x 10(8) colony-forming units (CFU) ml(-1)] and low (1 x 10(6) CFU ml(-1)) initial inoculum densities. Paenibacillus polymyxa GBR-1 showed strong starch-hydrolytic activity on modified starch agar with relatively low starch content, but only at certain incubation temperatures (18 and 23 degrees C); the high-density inoculum produced bacterial colonies about nine times thicker than those formed from the lower inoculum density. Light, scanning electron, and transmission electron microscopy showed that the thick colonies from the high-density inoculum were filled with extracellular polymeric substances (EPS), in which a relatively small number of ovoid-rod-shaped bacterial cells (mostly endospore-bearing cells) were distributed. In contrast, the thin colonies from the low-density inoculum were composed of massive vegetative cells with a rectangular rod shape and minimum EPS. Fluorescent in situ hybridization (FISH) revealed that the beta-amylase gene was expressed only in bacterial cells from the thick colonies formed from the high-density inoculum, but not in those from the low-density inoculum. The culture filtrate from the thick colonies produced a hydrolytic clear zone on modified starch agar, degraded starch granules in various manners, and produced rot symptoms on ginseng root tissues. The biological properties of colony formation, starch hydrolysis, and ginseng tissue rotting by P. polymyxa GBR-1 are interrelated; they are influenced by the initial bacterial population density but not by the in situ and the final population densities. Knowledge of disease-inducing characters of P. polymyxa GBR-1 can be used in the development of biocontrol strategies.

환수율 및 접종밀도에 따른 초소형 rotifer, Synchaeta kitina의 대량배양

The productivity of ultra-small rotifer, Synchaeta kitina was investigated at the exchange rate of culture water (10, 20, 30, 40 and 50%) and initial inoculation densities (250, 600 and 900 inds. per mL) in semi-continuous culture. Also, the possibility of mass culture was investigated in a 100 L culture tank. Tetraselmis suecica was used as the feed for S. kitina in all experiments. The production of S. kitina increased with an increase in exchange rate of culture water. The highest production ( inds.) was achieved at 40% exchange rate of culture water. The production of S. kitina increased with an increase of initial inoculation density during the first week and the highest total production ( inds.) was achieved at 900 inds. per mL of initial inoculation density. However, on the second week, all treatments were not significantly different in total production (P>0.05). During the two weeks, total production of S. kitina at 900 inds. per mL of initial inoculation density was higher than at 600 inds. of initial inoculation density, but there was no significant difference (P>0.05). In the 100 L culture tank, density of S. kitina was kept from 516 to 890 inds. per mL and S. kitina was daily harvested to during the experimental period. The production cost for 100 million rotifers in semi-continuous culture was 63,656 won. The results from this study indicate that the optimal exchange rate of culture water and initial inoculation density for the semi-continuous culture of ultra-small rotifer, S. kitina are 40% and 600 inds. per mL, respectively.

Relevance of microbial interactions to predictive microbiology

Microbial interaction can be ignored in predictive microbiology under most conditions. We show that interactions are only important at high population densities, using published data on inhibition of growth of Listeria monocytogenes in broth. Our analysis using growth models from predictive microbiology indicated that interactions only occur at population densities of ∼10 8 cfu/ml of the protective cultures. Spoilage is evident at these levels, except for fermented foods. In bacterial colonies, diffusion limitation acts as a constraint to growth. We have shown that these constraints only become important after large outgrowth of colonies (in the order of 5-log growth in Lactobacillus curvatus colonies), which depends on the initial inoculation density. Intra-colony interactions play an important role under these conditions. There is no large outgrowth of colonies when the initial inoculation densities are high and broth culture growth can be used to approximate colony growth.

Modeling the interactions of Lactobacillus curvatus colonies in solid medium: consequences for food quality and safety.

The growth process of Lactobacillus curvatus colonies was quantified by a coupled growth and diffusion equation incorporating a volumetric rate of lactic acid production. Analytical solutions were compared to numerical ones, and both were able to predict the onset of interaction well. The derived analytical solution modeled the lactic acid concentration profile as a function of the diffusion coefficient, colony radius, and volumetric production rate. Interaction was assumed to occur when the volume-averaged specific growth rate of the cells in a colony was 90% of the initial maximum rate. Growth of L. curvatus in solid medium is dependent on the number of cells in a colony. In colonies with populations of fewer than 10(5) cells, mass transfer limitation is not significant for the growth process. When the initial inoculation density is relatively high, colonies are not able to grow to these sizes and growth approaches that of broth cultures (negligible mass transfer limitation). In foods, which resemble the model solid system and in which the initial inoculation density is high, it will be appropriate to use predictive models of broth cultures to estimate growth. For a very low initial inoculation density, large colonies can develop that will start to deviate from growth in broth cultures, but only after large outgrowth.

Competition between the Rotifers Brachionus patulus and Euchlanis dilatata: Effect of Algal Food Level and Relative Initial Densities of Competing Species

We tested the effect of different algal (Chlorella vulgaris) levels and inoculation densities on the outcome of competition between the rotifers Euchlanis dilatata and Brachionus patulus. The experiment was performed in 36 transparent jars, each with 20 ml of a test medium. We used three Chlorella levels: 0.75 × 106, 1.5 × 106, and 3.0 × 106 cells/ml. For each algal level, we used five different ratios of initial inoculation density. The population growth experiments were terminated after 19 days. Regardless of inoculation densities, an increase in food level resulted in an increased population abundance of both rotifer species. Regardless of food concentration,E. dilatatawas able to outcompete B. patulus at all inoculation densities when grown together. However, when Chlorella was offered in low concentration and there was a higher ratio of Brachionus to Euchlanis at the onset of the experiment, both rotifer species coexisted in more or less equal densities until the end of the experiments. When the food level was enhanced, E. dilatata totally eliminated B. patulus. The rate of population growth ranged from 0.002 to 0.578 for B. patulus and from 0.006 to 0.447 for E. dilatata. The results are discussed with respect to the factors influencing the outcome of competition between species.

Competition between Brachionus calyciflorus Pallas and Brachionus patulus (Müller) (Rotifera) in relation to algal food concentration and initial population density

Competitive laboratory experiments between Brachionus calyciflorus and B. patulus were conducted at low (1×106 cells ml−1) and high (3×106 cells ml−1) densities of Chlorella vulgaris and four initial inoculation densities (numerically, 100% B. calyciflorus; 75% B. calyciflorus + 25% B. patulus; 50% each of the two species; 25% B. calyciflorus + 75% B. patulus and 100% B. patulus). Population densities were enumerated and the medium was changed daily for 20 days. B. patulus was a superior competitor in low food density regardless of inoculation density. At high food density, B. calyciflorus showed higher population growth in the first week but thereafter was outcompeted by B. patulus regardless of initial density. When grown alone, B. calyciflorus reached peak abundances (mean ± standard error) of 31±3 and 81±7 individuals ml−1 at low and high food densities, respectively. The corresponding values for B. patulus were 130±2 and 306±13. The adverse effects of B. patulus on the peak abundances of B. calyciflorus were higher at low food concentration. Data on egg ratios (eggs female−1) revealed an inverse relation with population abundance of both tested rotifer species. Our results indicated that the rate of population increase of a species was not a good indicator of its competitive ability. Instead, the ability to reproduce under continuously diminishing food resources (until a threshold level) was responsible for the competitive edge of B. patulus over B. calyciflorus. This was further influenced by the relative inoculation densities of the tested rotifer species and the offered food densities.

Impact of the parasite,Chrysomelobia labidomeraeEickwort, on the Colorado potato beetle

ABSTRACT Laboratory and field studies were conducted at the University of Rhode Island and in Cuernavaca, Mexico to determine the impact of parasitism by Chrysomelobia labidomerae Eickwort on the Colorado potato beetle, Leptinotarsa decemlineata (Say). Mite infestation significantly reduced longevity of adult Colorado potato beetles in the laboratory (an average of 40% over all treatment combinations). Longevity shortened with increasing initial mite inoculation density. Temperature did not affect this relationship, but the source of the mite population can affect the level of mortality in infested beetles. Beetles in field cages in Rhode Island, U.S.A. did not die from mite infestation and there was no reduction in beetle fecundity or overwintering success. Experiments in Mexico showed that mite infested beetles initiated flight less often than non-infested beetles and flew shorter as mite density increased.