温湿度对安徽虫瘟霉在桃蚜居群中流行的影响

用安徽虫瘟霉(Zoopphthoraanhuiensis)接种桃蚜(Myzuspersicae)无翅成蚜3头和健蚜3头组成新的蚜群若干,在不同温湿组合条件下任其繁殖、发病和传染,以评价温湿度对该菌在蚜群中流行的影响.持续26d观察,在偏低温与各湿度(90～100%RH)的组合中均成功诱发了蚜病流行,其程度受湿度影响较小.在10℃与各湿度组合中,最终感病死亡率为72.9%～98.2%,15℃下为78.7%～94.4%,流行强度极大.而20℃下仅100%RH诱发了高强度流行病,其余湿度下感病死亡率仅为5.1%～12.8%.在25℃,100%RH下死亡率仅27.2%.与所有湿度组合中的对照蚜群相比,10℃下流行病控蚜效果为89.5%～96.9%,15℃下为96.1%～98.2%,20℃下为45.9%～85.7%,25℃下为56.4%～69.7%.逐步回归分析表明,安徽虫瘟霉引发的蚜病流行与温度及其相对湿度和蚜群带菌后天数的互作项密切相关(r2=0.82,a＜0.01),这些变量在很大程度上决定了安徽虫瘟霉是否在蚜群中流行.     

飞虱虫疠霉继发性感染对桃蚜数量增长的控制作用

用飞虱虫疠霉（Pandora delphaics)“孢子浴”接种的桃蚜(Myzus persicae)无翅成蚜在离体甘蓝菜叶片（65cm^2)上建立蚜群,在不同温度（10－30℃）和湿度（74％－100％RH）的组合条件下任其繁衍,发病和交互感染,以评价该菌的控蚜效果。在25个温,湿度组合处理（8次重复,每重复含3头接种成蚜)中,蚜群均不同程度的发病死亡,在历时30d的观察中,以高温（20－30℃）,高湿（95％RH）组合条件下的蚜群发病快且死亡率高,蚜尸上产生的孢子有效地引起若蚜继发性感染。与相同温度下不带菌的对照蚜群相比,次于30℃下,各湿度除个别例外,第8d的控蚜率达30％以上,第20d达80％以上。在10℃和15℃下,控蚜效果一般不如上述较高温度下,且与湿度的关联程度相对较低,但最大控蚜效果均发生在100％RH处理中。结果表明,飞虱虫疠霉用于蚜虫防治的潜力很大,值得深入研究和开发利用。     

Molecular Characterization and Imidacloprid Selectivity of Nicotinic Acetylcholine Receptor Subunits from the Peach-Potato Aphid Myzus persicae

The recent introduction of the chloronicotinyl insecticide imidacloprid, targeting insect nicotinic acetylcholine receptors (nAChRs), emphasises the importance of a detailed molecular characterisation of these receptors. We are investigating the molecular diversity of insect nAChR subunit genes in an important agricultural pest, the peach-potato aphid Myzus persicae. Two M. persicae alpha-subunit cDNAs, Mp alpha1 and Mp alpha2, have been cloned previously. Here we report the isolation of three novel alpha-subunit genes (Mp alpha3-5) with overall amino acid sequence identities between 43 and 76% to characterised insect nAChR subunits. Alignment of their amino acid sequences with other invertebrate and vertebrate nAChR subunits suggests that the insect alpha subunits evolved in parallel to the vertebrate neuronal nAChRs and that the insect non-alpha subunits are clearly different from vertebrate neuronal beta and muscle non-alpha subunits. The discovery of novel subtypes in M. persicae is a further indicator of the complexity of the insect nAChR gene family. Heterologous co-expression of M. persicae nAChR alpha-subunit cDNAs with the rat beta2 in Drosophila S2 cells resulted in high-affinity binding of nicotinic radioligands. The affinity of recombinant nAChRs for [3H]imidacloprid was influenced strongly by the alpha subtype. This is the first demonstration that imidacloprid selectively acts on Mp alpha2 and Mp alpha3 subunits, but not Mp alpha1, in M. persicae.     

Effect of temperature and humidity on development, survival and oviposition in laboratory populations of Eriworm, Philosamia ricini (Boisduval) (Lepidoptera Saturniidae)

Experiments were conducted on laboratory populations of Eriworm, Philosamia ricini Boisduval to study the effect of temperature and humidity on development, growth, survival and oviposition. Experiments were performed at four different temperatures (22 +/- 2 degrees C, 26 +/- 2 degrees C, 28 +/- 2 degrees C and 34 +/- 1 degrees C) each with three different humidities (50%, 70% and 90% relative humidity). Shortest developmental period (42 days) was observed in 28 +/- 2 degrees C and 70% RH. Longest developmental period was (63.6 days) observed in 22 +/- 2 degrees C at 50% RH. Highest larval weight (9.1 g) was found in 28 +/- 2 degrees C at 70% RH. Best pupal weight was observed in 26 +/- 2 degrees C at 70% RH. Weight of silk material was found to be maximum in 26 +/- 2 degrees C at 70% RH. Survival was best in 28 +/- 2 degrees C and 26 +/- 2 degrees C at 70% RH. Oviposition was found to be highest in 28 +/- 2 degrees C at 70% RH.     

温湿度对稻纵卷叶螟卵的联合作用

为了探讨温湿度在稻纵卷叶螟Cnaphalocrocis medinalis （Guenée）种群发展中的作用, 通过室内实验调查了不同温度和湿度组合下该蛾卵的发育历期、 胚胎发育情况、 孵化率和卵粒重量的变化。结果表明： 在相同温度下卵历期随相对湿度的增大而缩短, 孵化率随相对湿度的加大而提高。在22℃下低于46%的相对湿度显著降低了卵的孵化率, 而在25～34℃下低于66%的相对湿度会引起孵化率的显著降低, 37℃下卵无论在何种湿度中均不能孵化。在50%左右的低湿条件下, 温度高于28℃后卵也不能孵化。温度在22～31℃和相对湿度在77%～100%范围内, 卵的孵化率无显著差异, 这属于稻纵卷叶螟卵的适宜温湿度范围。稻纵卷叶螟卵的发育起点温度和有效积温分别为10.1±0.6℃和63.7±3.5日度。卵的孵化率（Y）与温湿系数（RH/T）间呈显著的逻辑斯蒂曲线关系Y=0.8662/[1+exp(17.4084-7.5714×RH/T)]。温湿系数在2.34以下时卵孵化率将低于50%, 而达到3.0左右时孵化率接近最高值。结论认为, 低湿造成的稻纵卷叶螟卵重量显著降低、 卵粒干瘪、 胚胎发育受阻是致死卵的主要原因。     

Erythrocyte sedimentation rate. I. Volume fraction dependence in saline solution

We have measured volume fraction dependence of the sedimentation curve of swine erythrocytes in a physiological saline solution at 10 degrees C, 20 degrees C, 30 degrees C and 40 degrees C. The sedimentation curves were found to consist of initial constant velocity region and final plateau region at the lower temperatures of 10 degrees C and 20 degrees C, while modified S-shaped curves were observed at the higher temperatures of 30 degrees C and 40 degrees C. The volume fraction dependence of the initial slope v of the sedimentation curve was fitted well to the following exponential type equation at all the temperatures: v = vs,exp (1 - H)exp[-(BH + CH2)] where vs,exp is the velocity in infinite dilution corresponding to the Stokes velocity and H is the volume fraction of erythrocytes. The volume fraction dependence of the relative velocity v/vs,exp was in close agreement with a semi-empirical equation derived for slurrys in the field of chemical engineering at the lower temperatures, while a small deviation between the observed and calculated curves was found at the higher temperatures. The volume fraction dependence of v at 20 degrees C was also analyzed on a theory recently developed by Oka. The explicit functional form of the medium up-flow factor phi (H) and the deformability factor f in the theory were determined using the experimental data.     

Pathogenicity of hyphomycet fungi to aphids Aphis gossypii Glover and Myzus persicae (Sulzer) (Hemiptera: Aphididae)

The aphids Aphis gossypii and Myzus persicae are cosmopolitan, poliphagous and damage cultivated plants. The effects of the entomopathogenic fungi Beauveria bassiana (isolate IBCB 66), Metarhizium anisopliae (isolate IBCB 121), Paecilomyces fumosoroseus (isolate IBCB 141) and Lecanicillium (= Verticillium) lecanii (isolate JAB 02) on third instar nymphs of A. gossypii and M. persicae were evaluated in the laboratory at 25 degrees C, 70 +/- 10% RH and 12h photophase. The aphids were transferred to petri dishes with a foliar disk (cotton or pepper) with a layer of 1 cm tick of agar-water. The fungi were applied in a suspension containing 1.0 x 106 to 1.0 x 108 conidia/ml. In the control treatment 1 ml of sterilized water was added to the foliar disks. The mortality of aphids was evaluated daily. B. bassiana and M. anisopliae caused 100% mortality at the seventh day after inoculation, for both species. L. lecanii was the fungus that provided mortality later in the aphids and M. persicae was more susceptible to both fungi than A. gossypii.     

Chemical and biological studies of the major DNA adduct of cis-diamminedichloroplatinum(II), cis-[Pt(NH3)2(d(GpG]], built into a specific site in a viral genome

A duplex Escherichia coli bacteriophage M13 genome was constructed containing a single cis-[Pt(NH3)2(d(GpG]] intrastrand cross-link, the major DNA adduct of the anticancer drug cis-diamminedichloroplatinum(II). The duplex dodecamer d(AGAAGGCCTAGA).d(TCTAGGCCTTCT) was ligated into the HincII site of M13mp18 to produce an insertion mutant containing a unique StuI restriction enzyme cleavage site. A genome with a 12-base gap in the minus strand was created by hybridizing HincII-linearized M13mp18 duplex DNA with the single-stranded circular DNA of the 12-base insertion mutant. The dodecamer d(TCTAGGCCTTCT) was synthesized by the solid-phase phosphotriester method and platinated by reaction with cis-[Pt(NH3)2(H2O)2]2+ (yield 39%). Characterization by pH-dependent 1H NMR spectroscopy established that platinum binds to the N7 positions of the adjacent guanosines. The platinated oligonucleotide was phosphorylated in the presence of [gamma-32P]ATP with bacteriophage T4 polynucleotide kinase and incorporated into the 12-base gap of the heteroduplex, thus situating the adduct specifically within the StuI site in the minus strand of the genome. Approximately 80% of the gapped duplexes incorporated a dodecanucleotide in the ligation reaction. Of these, approximately half did so with the dodecanucleotide covalently joined to the genome at both 5' and 3' termini. The site of incorporation of the dodecamer was mapped to the expected 36-base region delimited by the recognition sites of XbaI and HindIII. The cis-[Pt(NH3)2(d(GpG]] cross-link completely inhibited StuI cleavage, which was fully restored following incubation of the platinated genome with cyanide to remove platinum as [Pt(CN)4]2-. Gradient denaturing gel electrophoresis of a 289-base-pair fragment encompassing the site of adduction revealed that the presence of the cis-[Pt(NH3)2(d(GpG]] cross-link induces localized weakening of the DNA double helix. In addition, double- and single-stranded genomes, in which the cis-[Pt(NH3)2(d(GpG]] cross-link resides specifically in the plus strand, were constructed. Comparative studies revealed no difference in survival between platinated and unmodified double-stranded genomes. In contrast, survival of the single-stranded platinated genome was only 10-12% that of the corresponding unmodified single-stranded genome, indicating that the solitary cis-[Pt(NH3)2(d(GpG]] cross-link is lethal to the single-stranded bacteriophage.     

Density functional geometry optimization and energy calculations of calcium(II)-triphosphate complexes. Polyphosphates as possible dissolving agents for calcium pyrophosphate dihydrate crystals in chondrocalcinosis disease

Geometry optimizations and energy calculations have been carried out via molecular orbital methods at the density functional B3LYP/LANL2DZ level on the molecules PO3-, OPO3(3-), HOPO3(2-), CH3OPO3(2-), H(CH3OPO3)-, O(PO3)2(4-), HO(PO3)2(3-), CH2(PO3)2(4-), (CH3OPO2)O(PO3)3-, O(PO3)3(5-), HO(PO3)3(4-), (PO3)3(3-), (CH3OPO2)O(PO3)2(4-), [Mg[O(PO3)2)]]2-, [Ca[O(PO3)2]]2-, [Ca[CH2(PO3)2]]2-, [Ca[CH3OPO2)O(PO3)]]-, [Ca(PO3)3]-, [Ca[O(PO3)3]]3-, and [Ca[CH3OPO2)O(PO3)2]]2- with the aim to find reliable and easily accessible computational methods to simulate some phosphate-containing molecules of importance for the living cells and to study the energetics for protonation and metal-complex formation reactions. The analysis is part of a general investigation on phosphate-containing molecules as potential dissolving agents for calcium pyrophosphate dihydrate (CPPD) crystals which deposit in certain articular diseases. The basis set was expanded to 6-31G** for the P atoms for all the molecules investigated and to 6-31G* for the O atoms for OPO3(3-). Calculations at the semiempirical MNDO/d level were also carried out for comparison purposes on the free ligand molecules and on [Mg[O(PO3)2]]2-. The density functional analysis reproduced well the geometry found at the solid state via X-ray diffraction. The analyses of the geometrical parameters and the total electronic energy of the molecules shows that O(PO3)2(4-) and other di- and tri-phosphates are versatile ligands for divalent metal ions like Ca2+. The computed P-O-P bond angle for free O(PO3)2(4-) is 180 degrees and the conformation of the two PO3- groupings is staggered along the P...P vector. The linear arrangement for P-O-P is assisted by P-O pi interactions. The bending of the P-O-P angle when accompanied by a slight P-O(b) elongation requires a very small amount of energy; 4.65 kcal/mol to pass from 180 to 140 degrees , as calculated at the DFT level. The computed Ca-O and Mg-O bond distances for [M[O(PO3)2]]2- are 2.378 and 2.079A, when the metal ions link two oxygen atoms from each PO3 group. The computed Ca-O bond lengths for [Ca[CH3OPO2)O(PO3)]]- are 2.482 (PalphaO2) and 2.358A (PbetaO2), showing a significant lengthening for Ca-OPalpha, when compared to the pyrophosphate derivative. The Ca-O bond lengths for [Ca[O(PO3)3]]3- and [Ca[CH3OPO2)O(PO3)2]]2- are 2.251A and 2.525 (PalphaO2), 2.407 and 2.338 (PbetaO2), and 2.251 and 2.228A (PgammaO2), showing a shortening for the Ca-OPgamma bond upon methylation. The (Pbeta)O-Pgamma bond length increases significantly (0.09 A) upon Ca(II) coordination to (CH3OPO2)O(PO3)2(4-) via all the three PO3 groups. This latter result suggests that metal complexes of linear organic-triphosphates have a larger tendency to release the PgammaO3 group when compared to the free ligand molecules. The electronic contribution to the energy of the complex formation reaction for [Ca[CH2(PO3)2]]2- is only slightly higher (some 1.8 kcal) than that for [Ca[O(PO3)2]]2-; but is much higher (some 63 kcal) than that relevant to the formation of [Ca[CH3OPO2)O(PO3)2]]2-. (ABSTRACT TRUNCATED)     

Molecular crowding reduces to a similar extent the diffusion of small solutes and macromolecules: measurement by fluorescence correlation spectroscopy

Aqueous environments in living cells are crowded, with up to >50 wt% small and macromolecule-size solutes. We investigated quantitatively one important consequence of molecular crowding--reduced diffusion of biologically important solutes. Fluorescence correlation spectroscopy (FCS) was used to measure the diffusion of a series of fluorescent small solutes and macromolecules. In water, diffusion coefficients (D(o)w) were (in cm2/s x 10(-8)): rhodamine green (270), albumin (52), dextrans (75, 10 kDa; 10, 500 kDa), double-stranded DNAs (96, 20 bp; 10, 1 kb; 3.4, 4.5 kb) and polystyrene nanospheres (5.4, 20 nm diameter; 2.3, 100 nm). Aqueous-phase diffusion (Dw) in solutions crowded with Ficoll-70 (0-60 wt%) was reduced by up to 650-fold in an exponential manner: Dw = D(o)w exp (-[C]/[C]exp), where [C]exp is the concentration (in wt%) of crowding agent reducing D(o)w by 63%. FCS data for all solutes and Ficoll-70 concentrations fitted well to a model of single-component, simple (non-anomalous) diffusion. Interestingly [C]exp were nearly identical (11+/-2 wt%, SD) for diffusion of the very different types of macromolecules in Ficoll-70 solutions. However, [C]exp was dependent on the nature of the crowding agent: for example, [C]exp for diffusion of rhodamine green was 30 wt% for glycerol and 16 wt% for 500 kDa dextran. Our results indicate that molecular crowding can greatly reduce aqueous-phase diffusion of biologically important macromolecules, and demonstrate a previously unrecognized insensitivity of crowding effects on the size and characteristics of the diffusing species.     

1H NMR assignment and melting temperature study of cis-syn and trans-syn thymine dimer containing duplexes of d(CGTATTATGC).d(GCATAATACG)

The preparation and spectroscopic characterization of duplex decamers containing site-specific cis-syn and trans-syn thymine dimers are described. Three duplex decamers, d(CGTATTATGC).d(GCATAATACG), d(CGTAT[c,s]TATGC).d(GCATAATACG), and d(CGTAT[t,s]TATGC).d(GCATAATACG), were prepared by solid-phase phosphoramidite synthesis utilizing cis-syn and trans-syn cyclobutane thymine dimer building blocks (Taylor et al., 1987; Taylor & Brockie, 1988). NMR spectra (500 MHz 2D 1H and 202 MHz 1D 31P) were obtained in "100%" D2O at 10 degrees C, and 1D exchangeable 1H spectra were obtained in 10% D2O at 10 degrees C. 1H NMR assignments for H5, H6, H8, CH3, H1', H2', and H2" were made on the basis of standard sequential NOE assignment strategies and verified in part by DQF COSY data. Comparison of the chemical shift data suggests that the helix structure is perturbed more to the 3'-side of the cis-syn dimer and more to the 5'-side of the trans-syn dimer. Thermodynamic parameters for the helix in equilibrium coil equilibrium were obtained by two-state, all or none, analysis of the melting behavior of the duplexes. Analysis of the temperature dependence of the T5CH3 1H NMR signal gave delta H = 44 +/- 4 kcal and delta S = 132 +/- 13 eu for the trans-syn duplex. Analysis of the concentration and temperature dependence of UV spectra gave delta H = 64 +/- 6 kcal and delta S = 178 +/- 18 eu for the parent duplex and delta H = 66 +/- 7 kcal and delta S = 189 +/- 19 eu for cis-syn duplex. It was concluded that photodimerization of the dTpdT unit to give the cis-syn product causes little perturbation of the DNA whereas dimerization to give the trans-syn product causes much greater perturbation, possibly in the form of a kink or dislocation at the 5'-side of the dimer.     

Impact of alterations near the [NiFe] active site on the function of the H(2) sensor from Ralstonia eutropha

In proteobacteria capable of H(2) oxidation under (micro)aerobic conditions, hydrogenase gene expression is often controlled in response to the availability of H(2). The H(2)-sensing signal transduction pathway consists of a heterodimeric regulatory [NiFe]-hydrogenase (RH), a histidine protein kinase and a response regulator. To gain insights into the signal transmission from the Ni-Fe active site in the RH to the histidine protein kinase, conserved amino acid residues in the L0 motif near the active site of the RH large subunit of Ralstonia eutropha H16 were exchanged. Replacement of the strictly conserved Glu13 (E13N, E13L) resulted in loss of the regulatory, H(2)-oxidizing and D(2)/H(+) exchange activities of the RH. According to EPR and FTIR analysis, these RH derivatives contained fully assembled [NiFe] active sites, and para-/ortho-H(2) conversion activity showed that these centres were still able to bind H(2). This indicates that H(2) binding at the active site is not sufficient for the regulatory function of H(2) sensors. Replacement of His15, a residue unique in RHs, by Asp restored the consensus of energy-linked [NiFe]-hydrogenases. The respective RH mutant protein showed only traces of H(2)-oxidizing activity, whereas its D(2)/H(+)-exchange activity and H(2)-sensing function were almost unaffected. H(2)-dependent signal transduction in this mutant was less sensitive to oxygen than in the wild-type strain. These results suggest that H(2) turnover is not crucial for H(2) sensing. It may even be detrimental for the function of the H(2) sensor under high O(2) concentrations.     

Importance of lipids for queen fecundity and colony growth of Coptotermes formosanus (Isoptera: Rhinotermitidae)

The importance of lipids for queen fecundity and colony growth of Coptotermes formosanus Shiraki was studied. Groups of 100 incipient colonies of C. formosanus were reared on artificial diet containing nine different soy lecithin concentrations. Eggs were counted every 15 d for a 5-mo period at 27 +/- 1 degrees C, 93 +/- 5% RH, and 0:24 h (L:D) photoperiod. Fecundity per queen was estimated using a developmental rate-based graphic integration technique. At the end of a 1-yr period, the progeny of each colony was counted and recorded. Analysis of variance showed significant differences in queen fecundity and hatched progeny in colonies raised on various diets. Single linear regression analysis showed a small but significant linear increase in queen fecundity and hatched progeny per colony with increasing lecithin concentration. Increase in lecithin concentration explained approximately 2, 4, and 8% of the increase in queen fecundity of colonies surviving 6 mo and 1 yr and number of workers and soldiers in 1 yr-old colonies, respectively. This indicates that, although intake of lipids increases queen fecundity and colony growth of C. formosanus, other factors not measured in this study alone or in combination with lecithin play major roles.     

Influence of the protonation degree on the self-association properties of adenosine 5'-triphosphate (ATP)

The concentration dependence of the chemical shifts for the protons H-2, H-8 and H-1' of ATP has been measured in D2O at 27 degrees C under several degrees of protonation in the pD range from 1.5 to 8.4. The results at pD greater than 4.5 are consistent with the isodesmic model of indefinite noncooperative stacking, while those at pD less than 4.5 indicate a preference for the formation of dimeric stacks. The stacking tendency follows the series, ATP4- (K = 1.3 M-1) less than D(ATP)3- (2.1 M-1) less than 1:1 ratio of D(ATP)3-/D2(ATP)-2- (6.0 M-1) much less than D2(ATP)2- (approximately 200 M-1) much greater than D3(ATP)- (K approximately less than 17 M-1) (for reasons of comparison all constants are expressed in the isodesmic model). These results are compared with previous data for adenosine [Ado (K = 15 M-1) greater than 1:1 ratio of Ado/D(Ado)+ (6.0 M-1) greater than D(Ado)+ (0.9 M-1)] and AMP [AMP2- (K = 2.1 M-1) less than D(AMP)- (3.4 M-1) less than 1:1 ratio of D(AMP)-/D2(AMP) +/- (5.6 M-1) greater than D2(AMP) +/- (approximately equal to 2 M-1) greater than D3(AMP)+ (K less than or equal to 1 M-1)] to facilitate the interpretation of the results for the ATP systems. Stack formation of H2(ATP)2- is clearly favored by additional ionic interactions; this is confirmed by measuring via potentiometric pH titrations the acidity constants of H2(ATP)2- in solutions containing different concentrations of ATP. It is suggested that in the [H2(ATP)]4-(2) dimer intermolecular ion pairs (and hydrogen bonds) are formed between the H+(N-1) site of one H2(ATP)2- and the gamma-P(OH)(O)-2 group of the other; in this way (a) the stack is further stabilized, and (b) the positive charges at the adenine residues are compensated (otherwise repulsion would occur as is evident from the adenosine systems). A detailed structure for the [H2(ATP)4-(2) dimer is proposed and some implications of the described stacking properties of ATP for biological systems are indicated.     

Study of temperature-growth interactions of entomopathogenic fungi with potential for control of Varroa destructor (Acari: Mesostigmata) using a nonlinear model of poikilotherm development

AIMS: To investigate the thermal biology of entomopathogenic fungi being examined as potential microbial control agents of Varroa destructor, an ectoparasite of the European honey bee Apis mellifera. METHODS AND RESULTS: Colony extension rates were measured at three temperatures (20, 30 and 35 degrees C) for 41 isolates of entomopathogenic fungi. All of the isolates grew at 20 and 30 degrees C but only 11 isolates grew at 35 degrees C. Twenty-two isolates were then selected on the basis of appreciable growth at 30-35 degrees C (the temperature range found within honey bee colonies) and/or infectivity to V. destructor, and their colony extension rates were measured at 10 temperatures (12.5-35 degrees C). This data were then fitted to Schoolfield et al. [J Theor Biol (1981)88:719-731] re-formulation of the Sharpe and DeMichele [J Theor Biol (1977)64:649-670] model of poikilotherm development. Overall, this model accounted for 87.6-93.9% of the data variance. Eleven isolates exhibited growth above 35 degrees C. The optimum temperatures for extension rate ranged from 22.9 to 31.2 degrees C. Only three isolates exhibited temperature optima above 30 degrees C. The super-optimum temperatures (temperature above the optimum at which the colony extension rate was 10% of the maximum rate) ranged from 31.9 to 43.2 degrees C. CONCLUSIONS: The thermal requirements of the isolates examined against V. destructor are well matched to the temperatures in the broodless areas of honey bee colonies, and a proportion of isolates, should also be able to function within drone brood areas. SIGNIFICANCE AND IMPACT OF THE STUDY: Potential exists for the control of V. destructor with entomopathogenic fungi in honey bee colonies. The methods employed in this study could be utilized in the selection of isolates for microbial control prior to screening for infectivity and could help in predicting the activity of a fungal control agent of V. destructor under fluctuating temperature conditions.     

Functional response of Cosmoclopius nigroannulatus (Hem.: Reduviidae) to different densities of Spartocera dentiventris (Hem.: Coreidae) nymphae.

This study evaluated the functional response of the predator Cosmoclopius nigroannulatus on first instar nymphae of Spartocera dentiventris, both species associated with Nicotina tabacum. The experiment was carried out in laboratory conditions: 27 +/- 1 degree C; 80 +/- 5%, RH; 12 h, photophase. Ten newly emerged adults of each sex of C. nigroannulatus were used in each of five densities (5, 15, 25, 35, and 45 individuals) of S. dentiventris nymphae. The predators were observed every 24 h for five days, when the number of dead and/or consumed nymphae was recorded. The results showed a positive correlation between the number of ingested nymphae and the increase in prey density. Females ingested more nymphae than the males. The estimated handling time per prey (Th) was higher in males (3.07 h) than in females (1.93 h), with total handling time (Th x Na) increased with density. Other components of the functional response, such as attack rate (a'), searching time (Ts), and search efficiency (E) showed, in neither males nor females, a negative correlation regarding density. The results indicated a higher predatory efficiency in the females. The components of the functional response fitted significantly the randomic model of the Holling discs equation (Na = N [1 - exp[- a'(T - ThNa)]]), evidencing a functional response of type II.     

七星瓢虫成虫对烟蚜的捕食作用

对七星瓢虫CoccinellaseptempunctataL .成虫对烟蚜Myzuspersicae的捕食作用进行了定量研究。七星瓢虫成虫对烟蚜的功能反应属HollingⅡ型反应 ,拟合的圆盘方程为Na =1 .1 5 76Nt ( 1 +0 .0 0 3 48Nt) ,χ2 检验表明圆盘方程理论值与实测值相符。捕食选择试验表明在烟蚜、烟青虫Helicoverpaassaut(Guenee)卵和 1龄幼虫 3种猎物中 ,七星瓢虫成虫最喜好烟蚜。七星瓢虫成虫对自身密度的功能反应用Watt模型拟合为A =2 90 .0 3P-0 .7584,其捕食作用率与个体间相互干扰作用的关系用Hassell模型拟合为E =0 .8783 7P-0 .1 0 0 94。文中进一步就烟田中七星瓢虫的保护利用进行了讨论。     

环境因素对安徽虫瘟霉生长发育的影响

安徽虫瘟霉是目前仅发现于我国的重要蚜虫病原真菌,对桃蚜具有明显的自然控制作用。本研究了温度和紫外光对安徽虫瘟等固体培养性状及不同温湿度组合对安徽虫瘟霉分生孢子萌发的影响。