Restorative Morphogenesis in vitro in the Annual Medic in the Presence of Benzylaminopurine

Four annual medic species (Medicago orbicularis (L.) All., M. rigidula (L.) Desr., M. scutellata (L.) Miller, and M. rugosa Desr.) were used as model objects for studying the spectrum of morphogenetic reactions in vitro. The seeds were incubated on nutrient media with benzylaminopurine at different concentrations until germination and, thereafter, the explants of seedlings were cultivated in order to obtain primary calluses and morphogenetic structures. Normal and abnormal (with reduced root and/or apex) seedlings were cultivated in the presence of benzylaminopurine. Further cultivation of explants from the seedlings of both types showed a considerable intra- and interspecific polymorphism by the capacity for callusogenesis, frequency of primary restorative reactions, and pattern of microreproduction in vitro. In the control (the seeds were incubated on a hormone-free medium), no cases of microreproduction by way of organogenesis or somatic embryogenesis were observed. In all experimental variants, the restorative reactions preceded microreproduction in vitro.     

Role of the C-terminal pro-domain of aqualysin I in the maturation and translocation of the precursor across the cytoplasmic membrane in Escherichia coli

Aqualysin I, which is a subtilisin-type, extracellular protease secreted by Thermus aquaticus YT-1, is synthesized as a unique precursor bearing pro-domains at both N- and C-terminus of the mature protease domain as well as an N-terminal signal peptide. To investigate the function of the C-terminal pro-domain in maturation and export pathway of the precursor in E. coli cells, aqualysin I variants were constructed in which deletion mutants of the C-terminal pro-domain lacking its own signal peptide were inserted into pIN-III-ompA3. When E. coli harboring wild type and mutant plasmids were induced by 0.2 mM IPTG, active aqualysin I was produced by heat treatment at 65 °C. Aqualysin I precursors with deletions of more than 5 amino acid residues at the C-terminal end of pro-domain were much more rapidly processed than that of wild type, indicating that the C-terminal pro-domain functions as a inhibitor for processing of aqualysin I precursor. With the wild type, most of aqualysin I was present in membrane fraction (probably the outer membrane), whereas for the truncated mutants, it remained in the cytoplasm, indicating that for deletion mutants, their precursors expressed in cells were not translocated across the cytoplasmic membrane, despite the existence of an N-terminal signal peptide.     

天山北麓典型水库细菌多样性分析

为了探讨天山北麓中段水库细菌的多样性及其功能,选取蘑菇湖水库（MGW）、奎屯/车排子水库（KCW）、安集海水库（AJW）和八一水库（BYW）为典型水库进行宏基因组学分析。多点采集水库水样,收集水样中的微生物,CTAB法提取总DNA,用细菌16S rDNA通用引物扩增V3-V4区,扩增产物进行高通量测序,使用BLAST、USEARCH、QIIME等软件和在线工具分析水库细菌的多样性,使用PICRUSt软件和KEGG数据库预测细菌功能基因组成。结果表明,水库细菌分属18个门、38个纲和181个属,其中AJW的操作分类单元（Operational taxonomic units,OTUs）数量和多样性指数较高。4个水库菌群组成有一定的共性,在门分类阶元上优势菌为变形菌门（Proteobacteria）和拟杆菌门（Bacteroidetes）;在纲分类阶元上优势菌为黄杆菌纲（Flavobacteriia）;在属分类阶元上优势菌为黄杆菌属（Flavobacterium）。然而各水库菌群组成也存在较大差异,在变形菌门中,γ-变形菌纲（Gammaproteobacteria）的相对丰度在MGW和BYW较高,α-变形菌纲（Alphaproteobacterial）和β-变形菌纲（Betaproteobacteria）分别于AJW和KCW具有较高丰度;芽孢杆菌纲（Bacilli）在AJW和MGW具有较高丰度;相对丰度较高的菌属还包括AJW的动性杆菌属（Planomicrobium）、KCW的马赛菌属（Massilia）、MGW的不动杆菌属（Acinetobacter）和动性杆菌属以及BYW的假单胞菌属（Pseudomonas）和嗜冷杆菌属（Psychrobacter）;另外,AJW特有多种丰度较高的菌纲和菌属,其中微小杆菌属（Exiguobacterium）和CL500-29_marine_group均有利于水质和菌群多样性的维持。PICRUSt功能预测分析表明,4个水库菌群的多种代谢以及遗传信息处理、信号传递和细胞生长相关功能基因丰度较高,并含有环境异生物降解代谢相关基因,其中苯甲酸、氨基苯甲酸酯、氯烷烃和氯烯烃以及萘降解相关基因的相对丰度较高。以上结果提示,天山北麓中段不同水库菌群组成存在差异,其与水源、周边环境和人类活动等因素相关。水库菌群含有芳香族和有机氯等化合物降解相关基因,其可在污染物的降解和生物修复中发挥作用。     

Role of the immune-response region of the B complex in the control of the graft-vs-host reaction in chickens

The relative importance of the B and IR regions of the chicken B complex were compared as to their role in the graft-versus-host (GVH) reaction. Spleen enlargement (splenomegaly) on 19-day-old embryos, inoculated 5 days earlier with immune competent leukocytes, served as the test for the GVH reaction. The B blood group locus was the marker of the B region, and the Ir-GAT gene was the marker of the immune response (Ir) region of the B complex, the major histocompatibility system (MHS) of chickens. The test stocks consisted of B¹B¹ GAT-Low (1-Low) and B¹⁹B¹⁹ Gat-High (19-High) birds of our S1 Leghorn line plus the recombinant genotypes B¹B¹ Gat-High (1-High) and B¹⁹B¹⁹ GAT-low (19-Low). A dosage of 0.1 ml of donor white blood cells was injected into each of 191 recipient embryos on day 14, and the spleens were removed and weighed on day 19. Of 16 combinations of (donor blood)-(host embryos), arranged with respect to the four genotypes listed above, four were compatible, e. g., (1-Low)-(1-Low). There were four incompatible combinations at the B locus, four at the GAT locus, and four at both the B and GAT loci. All 16 combinations were replicated. Results were expressed as a splenomegaly index (SI), that is, the ratio of incompatible to compatible spleen weights corrected for differences in embryo weight. If (SI-1) is greater than 0, the GVH reaction is considered positive within sampling errors. The mean (SI-1) indexes obtained were: incompatible at GAT-0.5±0.07; incompatible at B-1.34±0.10. Thus, both GAT and B contributed to the GVH reaction, but the B region was much stronger than the IR region. The results were strongly asymmetrical: maximal stimulation occurred when the host embryo was B¹⁹B¹⁹ GAT-high and donor leukocytes were B¹B¹ GAT-Low. The parental donor-host paired combinations gave stronger GVH reactions than did the recombinant pairs. Effects of incompatibilities at the two regions proved additive when compared with two-locus differences of parental genotypes. In general, the results proved that the IR region, as specifically defined by recombinants obtained in our S1 line of Leghorns, plays a significant, but minor, role in the GVH reaction compared with the region of the B complex identified with the B blood-group locus.     

Analysis of the AluPolymorphism in the Buryat Populations

Polymorphism of three populations of the Buryat Republic and a population from Aginskii Buryat Autonomous okrug of Chita oblast was examined using a set of five autosomal Aluinsertions at theACE, PLAT, PV92, APOA1,and F13Bloci. The allele frequency distribution patterns revealed in Buryat populations were typical to other Asian populations. Buryats were characterized by relatively low level of intrapopulation diversity (0.369 in the pooled population sample). Analysis of autosomal Aluinsertions suggests the uniformity of the Buryat gene pool. The coefficient of genetic differentiation in the four populations studied was 0.8%.     

Physiological evidence for the involvement of peptide YY in the regulation of energy homeostasis in humans

Objective: To explore the potential role of the endogenous peptide YY (PYY) in the long‐term regulation of body weight and energy homeostasis. Research Methods and Procedures: Fasting and postprandial plasma PYY concentrations were measured after an overnight fast and 30 to 180 minutes after a standardized meal in 29 (21 men/8 women) non‐diabetic subjects, 16 of whom had a follow‐up visit 10.8 ± 1.4 months later. Ratings of hunger and satiety were collected using visual analog scales. Resting metabolic rate (RMR) (15‐hour RMR) and respiratory quotient (RQ) were assessed using a respiratory chamber. Results: Fasting PYY concentrations were negatively correlated with various markers of adiposity and negatively associated with 15‐hour RMR (r = ?0.46, p = 0.01). Postprandial changes in PYY (area under the curve) were positively associated with postprandial changes in ratings of satiety (r = 0.47, p = 0.01). The maximal PYY concentrations achieved after the meal (peak PYY) were negatively associated with 24‐hour RQ (r = ?0.41, p = 0.03). Prospectively, the peak PYY concentrations were negatively associated with changes in body weight (r = ?0.58, p = 0.01). Discussion: Our data indicate that the endogenous PYY may be involved in the long‐term regulation of body weight. It seems that this long‐term effect was not exclusively driven by the modulation of food intake but also by the control of energy expenditure and lipid metabolism.     

The reproductive phenology of nine species of Rhodophyta in the subtidal region of the Isle of Man

Monthly samples of about 40 separate plants of each species were collected from 1 to 3 m below lowest astronomical tide on Port Erin breakwater, Isle of Man, Irish Sea. In three species growing on rock, Plocamium cartilagineum, Cryptopleura ramosa and Callophyllis laciniata, about 90% of the plants were fertile in late summer but less than 10% in spring although some fertile plants were always present. Delesseria sanguinea and Odonthalia dentata, also epilithic, had a winter sporing season, Odonthalia extending into late spring, and all plants were sterile in summer. Three species growing epiphytically, Palmaria palmata, Membranoptera alata and Phycodrys rubens, reproduced maximally in the first half of the year at the time when the stipes of the host species, Laminaria hyperborea, grow fastest. Only Palmaria had a sterile season, late summer. The encrusting Cruoria pellita showed little seasonality. The first three species, which reproduce mainly when the sea temperature is above average, are in the northern part of their geographical range. The remaining species (apart from Cruoria) reproduce mainly at low temperatures and are in the southern half of their ranges. Male plants appear to be in a minority in all species, presumably because they were manifest for a shorter period than carposporic plants. They appeared first after sterile periods and were absent as sporing declined. Plocamium and to a lesser extent Cryptopleura show an extremely high preponderance of tetrasporophytes in the population. This is attributed to perennation and some factor disallowing the survival of most of the tetraspores.     

Spatial variability in the abundance of the corallivorous gastropod Drupella cornus

The corallivorous gastropod Drupella has been responsible for extensive coral mortality on a number of reefs in the Indo-West Pacific region. Seasonal and spatial variability in the abundance of juvenile (<2.0 cm shell length) and adult (>2.0 cm) Drupella cornus along the Ningaloo Reef, Western Australia, were documented during 1990/1991. Numbers of D. cornus were found to vary significantly between the different sites and reef habitats sampled, with the highest numbers recorded at a backreef edge site at the southern end of the reef. There was no evidence that the densities of D. cornus varied seasonally, although size-frequency distributions suggest that there may have been a recruitment peak in January/February 1991 following a major spawning event in November/December 1990. Drupella cornus were found predominantly on Acropora species with a caespitose/corymbose growth form; however the abundance of these corals at different sites did not explain the observed distribution patterns of the gastropod. Drupella cornus recruits (<1.0 cm shell length) frequently occurred on corals which were also occupied by larger conspecifics, suggesting that either larval settlement or post-settlement survival were increased in the presence of adult D. cornus.     

Association of genetic polymorphisms with fertilization in the chicken

Summary Associations between fertilization rate and genotypes at four polymorphic loci were studied in three relatively non-inbred populations of Light Sussex chickens. In sires the genotypes tested were at theB blood-group locus only; in dams, at theB locus and three egg-white loci. Data were available for purebred matings of related substrains 6D and 6F and the ancestor strain 6 from which they were derived and for crossbred matings of 6D and 6F by two related Rhode Island Red/New Hampshire strains.In analyses of variance by dam genotypes within sires, no locus or combination of loci had a significant effect on fertilization rate. In analyses by sire and damB blood-group genotypes, no significant effects were found in 6F. SireB genotypes showed a very significant effect (P<0.001) on fertilization rate in 6D, and in 6. The latter effect was not fully acceptable since there was a significant (P<0.02) sirex damB genotypes interaction effect in 6. This interaction took the form of a lowered fertility in matings where sire and dam had the sameB genotype. The significant main effect in 6D was due to significant differences between the fertilization rates of the three most frequent sire genotypes. The same differences were not found in the other two strains. Similarly, significant sireB genotype differences in the Rhode Island Red/New Hampshire mates of 6F were not repeated in those of 6D.Combination of this result with those from our previous work with embryonic mortality in these strains is still insufficient fully to explain the continued segregation of four alleles at theB blood group locus.     

Microbiological Analysis of Stuffed Mussels Sold in the Streets

Stuffed mussel is a traditional food that sold by street venders in various countries. In the present study, samples of stuffed mussels were collected from various places in Ankara. The mussels were analyzed to show the microbiological risks for human health. Thirty samples (600 stuffed mussels in total) were collected periodically and microbiological analyses were performed by standard procedures for Bacillus cereus, Staphylococcus aureus, Escherichia coli, Salmonella sp., Clostridium sp. In terms of Salmonella sp., approximately 50% of samples were not suitable for consumption. Besides, in accordance with Turkish Food Codex Microbiological Criteria Announcement in terms of E. coli 30%, in terms of B. cereus 80%, in terms of S. aureus 76.6%, in terms of Clostridium perfringens 13.3% of these samples were not suitable for consumption. The aim of this study is to discuss the microbiological quality of stuffed mussels as a ready-to-eat food according to Turkish Food Codex (TFC). The result of this investigation indicates that stuffed mussels as a street food may constitute a potential health hazard, depending on contamination level and lack of sanitary practices, and therefore, handling practices should require more attention and improvement.     

The mysid-feeding guild of demersal fishes in the brackish zone of the Westerschelde estuary

The demersal fish fauna of the mesohaline zone of the Westerschelde estuary (south-west Netherlands) was sampled intensively in the period 1990–1992. Almost 500 beam trawl samples were taken in both subtidal (330 samples) and intertidal (144 samples) habitats. These yielded 44 fish species, mostly as juveniles. The area functioned as a nursery for several demersal fish species, and harboured large populations of hyperbenthic mysids. Three gobies, three flatfish, one clupeoid and one gadoid dominated the fish fauna, while three mysid species were important components of the holohyperbenthos. From c. 1500 stomach contents of 25 fish species, 44 prey species were identified, the most abundant of which were also common in the hyperbenthal. The demersal fish community consisted of a group that foraged subtidally on fast-moving epi-and hyperbenthic prey (for example gadoids, gobies and clupeoids) and a group that foraged on slow-moving or sessile endobenthic organisms, mainly in intertidal areas (for example most flatfish species). Mysidacea occurred in >50% stomachs analysed and were taken as prey by 19 of the 25 fish species. Mysids were most important in the diets of Pomatoschistus minutus, P. lozanoi, Trisopterus luscus and Merlangius merlangus, and were present in appreciable numbers in Pleuronectes flesus, Trigla lucerna, Clupea harengus and Pleuronectes platessa. These species fed mainly on the brackish water endemic Neomysis integer. Mesopodopsis slabberi (present in 35% of the gobiid stomachs) and Gastrosaccus spinifer(present in 25% of the gadoid stomachs) were of secondary importance. P. minutus and T. luscus showed a diet shift from calanoids (Eurytemora aYnis and Temora longicornis) to mysids at L_S of 30 and 50 mm, respectively. Only 1% of the standing stocks of the N. integer and M. slabberi populations was removed by the local demersal fish community, so top–down control of mysid populations in estuaries seems unlikely.     

The cooperative effect of the Satin and Beige mutations in the suppression of NK and CTL activities in mice

The functional activity of natural killer (NK) cells has been found to be modulated by several point mutations associated with coat color. The most commonly studied gene, beige (Bg), has been found to block a postrecognition event in the lytic cycle. Four other coat color mutations in the mouse (satin, leaden, fuzzy, pale ears) were studied for their effect on NK cell function, and only one, satin (Sa), was found to be suppressive. When both the Sa and Bg mutations were present in the same animal, their effects were synergistic in the suppression of NK levels. Normal numbers of NK cells were present in these double mutants, as determined by the frequency of IgG2b binding cells and by antiasialo GM1 staining. The ability of Sa/Bg NK cells to recognize and bind targets suggests that the defect is localized in the postbinding cytolytic pathway. These genes were not specific for NK cells and also suppressed alloimmune cytolytic T lymphocyte function. Since Sa/Bg mice are much more suppressed in NK function than Bg mice, we suggest that this double mutant may be a better model for NK deficiency in vivo.     

Genetic mapping of the Isaac-CACTA transposon in maize

We constructed a genetic linkage map with Isaac-TD, SSR, and SNAP markers in a RIL population which had been derived from a cross of waxy corn (KW7) and dent corn (Mo17). A total of 368 markers, including 241 Isaac-TD, 121 SSR, and 6 SNAP markers, were assigned to 10 linkage groups, encompassing 1687.0 cM, with an average genetic distance of 4.6 cM between markers. SSR markers were utilized as chromosome anchors, in order to assign the Isaac-TD markers to the chromosomes, and the number of markers in each of the linkage groups ranged between 22 and 49. The majority of the Isaac-TD markers were determined to have been distributed throughout the ten maize chromosomes. In linkage analysis of the Isaac-TD markers with genes of agronomic interest, six genes related with maize kernel starch biosynthesis, ae1, bt2, sh1, sh2, su1, and wx1, were analyzed and shown that they were closely linked with either the Isaac-TD or SSR markers on chromosomes of 3, 4, 5, and 9. We observed and mapped segregation-distorted markers on chromosomes 1, 5, 6, 7, 8, and 10, where these markers were clustered. The Isaac-TD or SSR markers which were closely linked with starch synthesis genes may prove useful in marker-assisted breeding programs.     

Allozyme variation among biotypes of the brown planthopperNilaparvata lugens in the Philippines

Allozyme variation was studied in threeNilaparvata lugens biotypes infesting specific rice varieties and a biotype infesting a weed grass,Leersia hexandra. Of the 20 enzymes inN. lugens for which activity was noted, 9 were polymorphic. Eleven enzyme loci were monomorphic for the same allele in all biotype populations; the rest were polymorphic for two or more alleles. The mean number of alleles per polymorphic locus was 2.3, while the mean number of alleles per locus was 1.5; heterozygosity ranged from 0.02 to 0.06 (biotype 1 > biotype 3 >Leersia-infesting biotype > biotype 2). Allelic frequency differences were observed in five loci among the four biotypes. However, the coefficient of genetic identity (I) of 0.99+ showed that the four biotype populations were genetically close relatives or merely populations ofN. lugens undergoing genetic differentiation. This work was partly supported by a financial grant received from the Directorate for Technical Cooperation and Humanitarian Aid, Switzerland.     

The structure of the chloroplast genome in members of the genus Asparagus

 In a previous study we constructed a physical map of the chloroplast DNA (ctDNA) of garden asparagus (Asparagus officinalis L. cv ‘Mary Washington 500W’; Lee et al. 1996). In the present study we have constructed and compared HindIII and XhoI restriction maps of the ctDNAs of eight species of Asparagus: namely, A. officinalis, A. schoberioides, A. cochinchinensis, A. plumosus, A. falcatus, A. sprengeri, A. virgatus and A. asparagoides. The ctDNA of A. officinalis has 32 and 23 sites that are recognized by HindIII and XhoI, respectively. Taking the physical map of the ctDNA of A. officinalis as a standard, we found that the ctDNAs of A. falcatus, A. sprengeri, and A. asparagoides each had one additional HindIII site and lacked one XhoI site. We also detected two relatively large deletions of nucleotides in the ctDNA from A. cochinchinensis by sequencing analysis. Both of these deletions were located in a non-coding region between the ndhC and trnV genes and were 95 bp and 347 bp in length, respectively. The regions around the deletions exhibited strong homology, and short direct-repeat sequences were detected at the borders of the deletions, an indication that these deletions were the result of intramolecular recombination mediated by the direct repeats. Received: 16 June 1997 / Accepted: 17 July 1997     

Eimerian infection in the gut of the tube-nosed gobyProterorhinus marmoratus (Pallas) of the River Danube

A mixed infection with twoEimeria species,E. credintsi Moshu, 1992 andE. marmorata n. sp., was found in the gut of the tube-nosed goby of the River Danube basin. Sporulated oöcysts ofE. credintsi and unsporulated and semisporulated oöcysts ofE. marmorata were found freely in the gut lumen. Sporocysts ofE. credintsi open at the cap-like end, releasing sporozoites through a funnel-shaped opening. Sporocysts ofE. marmorata open at the tapered end, forming a fissure alongside the suture reaching up to half the length of the sporocysts. In histological preparations, both species were found in the intestinal epithelium. Merogonic and sporogonic stages ofE. credintsi and gamogonic and sporogonic stages ofE. marmorata were detected in the epithelium of the anterior part of the gut.     

Seasonal Changes in Lorica Sizes and the Species of Tintinnida in the New York Bight*

SYNOPSIS. Tintinnida of the New York Bight (a bend in the coastline) were identified during the 1-year period August 1973–August 1974. Recurring genera included Stenosemella and Tintinnopsis; seasonal genera were mainly the hyaline Favella, Metacylis, and Helicostomella; exotic or unusual genera included Parafavella and Ptychocylis. Large size differences in loricae were found seasonally, related apparently, to water temperature.     

Coding of vibration by neurones of the dorsal column nuclei in the pigeon

Whereas the function of mechanoreceptors is well known in birds there are no detailed investigations of central processing. Therefore the characteristics of neurones in a first relay, the dorsal column nuclei (nuclei gracilis et cuneatus and the nucleus cuneatus externus), were studied electrophysiologically by recording responses from individual neurones to mechanical stimulation of skin and deep tissue.Of 140 units 84 were cutaneous neurones. The remainder were tap- and deep-neurones. Tap-neurones were activated by sharp brief taps. Activity in deep-neurones was comparable to joint and tendon receptors but not to muscle spindles. Thirty-four cutaneous neurones were vibration sensitive neurones, 36 were slowly adapting neurones and 14 neurones were rapidly adapting and fast habituating cells. Vibration sensitive neurones were most sensitive to 200 to 500 Hz. Frequencies above 100 Hz elicited phase coupled responses.Within the nn. gracilis et cuneatus 61 were cutaneous neurones, 13 were deep-neurones and 7 were tap-cells. Within n. cuneatus externus 17 were cutaneous units, 21 were deep-neurones and 11 were tap-neurones. No vibration sensitive neurones were found within n. cuneatus externus. This means that coding for vibration is represented in the nn. gracilis et cuneatus.Abbreviations CE n. cuneatus externus - DCN dorsal column nuclei - GC n. gracilis et cuneatus - HC Herbst corpuscle - PH phasic and habituating - Imps./s Impulses per second - INTH interval histogram - PSTH peristimulus time histogram - PHASE Phase histogram - RF receptive field - SA slowly adapting - Vec. vector strength     

Effects of the ice-edge bloom and season on the metabolism of copepods in the Weddell Sea,Antarctica

The metabolic responses of several species of Antarctic copepods to primary productivity and changes between seasons were investigated. To examine the influence of the spring ice-edge bloom on the metabolism of copepods, oxygen consumption rates were determined on specimens from three zones of widely different ice coverage and chlorophyll biomass: pack ice (pre-bloom), ice edge (bloom) and open water (post-bloom). Summer metabolic rates were compared with published winter rates. Field work was done in the Weddell Sea in the region of 60 °S, 36°W in late November and December 1993. Oxygen consumption rates were determined by placing individuals in syringe respirometers and monitoring the oxygen partial pressure for 10–20 hours. Higher metabolic rates were observed in the primarily herbivorous copepods, Calanoides acutus, Rhincalanus gigas and Calanus propinquus in regions of higher primary production: ice edge and open water. The carnivorous Paraeuchaeta antarctica showed a similar pattern. The omnivorous copepods Metridia gerlachei and Gaetanus tenuispinus showed no changes in metabolism between zones. Data on routine rates of copepods from the winter were available for C. propinquus and P. antarctica. In P. antarctica, rates were higher in the summer. Calanus propinquus showed a higher metabolic rate in the summer than in the winter, but the difference was not significant at the 0.05 level. It was concluded that copepods near the ice zone in the ice zone in the Antarctic rely on the spring ice-edge bloom for growth and completion of their life cycle.     

Importance of predation by Coleomegilla maculata larvae in the natural control of the corn earworm in sweet corn

The corn earworm, Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) is a serious pest of many crops in North America, particularly sweet corn. The larvae of Coleomegilla maculata (DeGeer) (Coleoptera: Coccinellidae) are the most frequently observed predators of H. zea eggs in sweet corn. Companion cropping strategies have been developed to augment densities of C. maculata in sweet corn plantings. In this study, the importance of predation by C. maculata larvae was evaluated in experiments when larval abundance was manipulated using hand removal and physical exclusion. In 2003 and 2004, sentinel H. zea eggs were exposed on corn for 48 h. Egg mortality was 13.8% greater in the treatment where C. maculata larvae were present. In 2004 and 2005 eggs were exposed on corn under the same hand removal and physical exclusion techniques and monitored at 3-h intervals for 24 h to directly observe predation on sentinel eggs. Coleomegilla maculata larvae were the most frequently observed predators of the eggs, accounting for 45.9% of 85 total observed predation events in the control. Whereas in the treatment where C. maculata larvae were reduced, egg survival was 26.13% greater and only 37 total predation events were observed. All pest eggs were eliminated from individual ears 22.1% more often when C. maculata larvae were present at natural densities indicating that predation by this predator stage lessens crop damage by H. zea. The results of this study suggest that C. maculata larvae are an irreplaceable source of natural mortality for H. zea eggs on sweet corn.