Eggs Of Other Species Research Articles

A simple way to calculate the volume and surface area of avian eggs.

Egg geometry can be described using Preston's equation, which has seldom been used to calculate egg volume (V) and surface area (S) to explore S versus V scaling relationships. Herein, we provide an explicit re-expression of Preston's equation (designated as EPE) to calculate V and S, assuming that an egg is asolid of revolution. The side (longitudinal) profiles of 2221 eggs of six avian species were digitized, and the EPE was used to describe each egg profile. The volumes of 486 eggs from two avian species predicted by the EPE were compared with those obtained using water displacement in graduated cylinders. There was no significant difference in V using the two methods, which verified the utility of the EPE and the hypothesis that eggs are solids of revolution. The data also indicated that V is proportional to the product of egg length (L) and maximum width (W) squared. A 2/3-power scaling relationship between S and V for each species was observed, that is, S is proportional to (LW2 )2/3 . These results can be extended to describe the shapes of the eggs of other species to study the evolution of avian (and perhaps reptilian) eggs.

Density, Temperature, and Comingled Species Affect Fitness within Carrion Communities: Coexistence in Phormia regina and Lucilia sericata (Diptera: Calliphoridae)

Blow fly (Diptera: Calliphoridae) interactions vary between competition and facilitation. Female blow flies engage in aggregated egg-laying, resulting in larval feeding masses differing in density and species composition. Numerous species are abundant within the same season, and some oviposit near or directly on eggs of other species, modifying their oviposition location choice depending on the presence or absence of other species. The ability to coexist on carrion, a temporary resource, was successfully attributed to resource, spatial, and temporal heterogeneity. Despite these broad categorizations, the specific mechanisms of coexistence within blow fly communities require further investigation. This study investigates variation in temperature and larval density as potential mechanisms of coexistence between two forensically important blow fly species: Lucilia sericata Meigen and Phormia regina Meigen (Diptera: Calliphoridae). Larval density, species ratio mix, and ambient temperature during development were manipulated in the presence of conspecifics and heterospecifics in the laboratory, and the fitness of each species was measured. In heterospecific treatments, the survival and body size of P. regina increased even at high ambient temperatures. In contrast, the survival of L. sericata remained unaffected by density or presence of heterospecifics, whereas body size increased in L. sericata-dominated heterospecific treatments depending on temperature and density. The negative effects of density were observed at high ambient temperatures, suggesting that density impacts are a function of ambient temperature. Overall, species coexistence was dependent on temperature, which mediated the outcome of species interactions.

The degree of embryonic development influenced some eggshell characteristics of wild Red-tailed Hawks (Buteo jamaicensis borealis)

The influence of embryonic development on eggshell characteristics of wild birds, particularly raptors, is not well studied. Red-tailed Hawk (Buteo jamaicensis borealis (Gmelin, 1788)) eggs (n = 66) collected in central New York State (USA) during the late 1800s and early 1900s were examined to determine if eggshell mass, eggshell thickness, and a thickness index corrected for egg shape and blowhole size were influenced by the degree of embryonic development at the time of collection. Changes in these characteristics were examined with linear mixed models with year of collection and clutch size specified as random variables. Unexpectedly, length, breadth, and mass of eggshells were greater in eggs with advanced embryonic development than eggs with less developed embryos, perhaps due to sampling error or collector bias. Eggs containing well-developed embryos were 13% thinner and had a thickness index 7% smaller than eggs with poorly developed embryos. Eggs with larger embryos had larger blowhole diameters; this relationship may be useful in determining degree of embryonic development in eggs of other species where development information is not explicit. Given the historical and current interest in eggshell thinning due to pollutants, degree of embryonic development should be accounted for in studies of eggshell characteristics.

Short-chain chlorinated paraffins in various foods from Republic of Korea: Levels, congener patterns, and human dietary exposure

Short-chain chlorinated paraffin (SCCP) concentrations in 419 food samples (from 59 species) from Republic of Korea were determined. The SCCP concentrations and lipid contents in whole foods positively correlated and the highest SCCP concentration (891 ng/g wet weight) was observed in fats and oils. The SCCP concentrations were higher in benthic fish/shellfish and demersal fish than other fish and shellfish. The SCCP concentrations were higher in duck meat and eggs than meat and eggs of other species. The chlorine-based congener group patterns were related to the lipid contents of the foods. SCCPs in eggs (high lipid content) were dominated by more-chlorinated SCCPs (particularly Cl8-SCCPs, which contributed 43% of the total) but SCCPs in seaweed (low lipid content) were dominated by less-chlorinated SCCPs (particularly Cl6-SCCPs, which contributed 46%). Dietary SCCP intakes were calculated using the median SCCP concentrations and estimated 888 and 781 ng/kg/d for male and female Korean adults, respectively. The predominant contributing foods to SCCP dietary exposure differed according to sex and age. Dairy products contributed most (about 50%) for infants/children (1–5 y old), but meat and dairy products contributed most for adult males and females, respectively. Grain contributed most for ≥65 y old.

<p class="HeadingRunIn"><strong>Experimental hybridization of sympatric temnopleurid sea urchins living in Yamaguchi, Japan</strong></p>

Three sympatric species of temnopleurid sea urchins, Temopleurus toreumaticus (Leske, 1778), T. hardwickii (Gray, 1855) and Mespilia globulus (Linnaeus, 1758), occupy a habitat located a short distance from the shore of the Seto Inland Sea, Yamaguchi Prefecture, Japan. Breeding seasons overlap considerably among these species. These species exhibit species-specific differences in embryonic and larval development such as a wrinkled zygote, wrinkled blastula, archenteron invagination, larval skeleton and juvenile morphology. In this study, we determined whether interbreeding among these species is possible. Investigations revealed that fertilization succeeded with all mating combination patterns and that all fertilized eggs developed to the gastrula stage. The blastula and gastrula of hybrids formed in a manner similar to the maternal whereas the developmental delay observed followed the pattern of the paternal species T. toreumaticus fertilized at a greater proportion than other pairs and metamorphosed. These results suggest that eggs of this species may have weaker fertilization block in general. At the early developmental stages, hybrid embryos from T. toreumaticus mothers express maternal, while some hybrids derived from sperm of T. toreumaticus and the eggs of other species ceased development at the 4-armed larval stage. The hybrids of T. hardwickii and M. globulus ceased development at the gastrula stage, suggesting that these species have a greater degree of genetically isolation distance. In hybrids of T. toreumaticus and strongylocentrotid Hemicentrotus pulcherrimus (A. Agassiz, 1864), larval skeletons expressed features from both species. These results suggest that traits of hybrids are derived not only from one or both original species, but that a mosaic effect can be obtained depending on the traits. These results indicate that temnopleurids have the weaker fertilization block mechanisms. Isozyme analyses showed that hybrid prisms of T. toreumaticus eggs and M. globulus sperm possess enzymatic patterns of malate dehydrogenase derived from each parent, whereas the enzymatic pattern of glucose-6-phosphate dehydrogenase is derived from eggs, suggesting that malate dehydrogenase activity may be useful in detecting naturally occurring adult hybrids among these species in the Yamaguchi coastal area.

Effects of Storage on Physico-Chemical Parameters and Quality of Greater Rhea (Rhea Americana) Eggs

The Greater Rhea ( Rhea americana) is a member of Brazilian fauna with potential for the production of eggs with a unique nutritional composition that differs from the eggs of other species. The present study aimed to gather information regarding the centesimal composition of Greater Rhea eggs and the storage time for the preservation of egg quality for human consumption. Twenty-five Greater Rhea eggs (albumen and yolk fractions), distributed into five groups of eggs stored for 7, 14, 21, 28 and 35 days at 10 °C, were analysed. For the determinations of the percentage composition, total protein was quantified by the Kjeldahl method and total lipids by the Soxhlet method. To assess egg quality, the Haugh unit (HU), pH, and protein degradation (by SDS PAGE electrophoresis) were determined. Based on the results, the albumen protein fraction quality was maintained for 21 days, while the yolk proteins began to denature on the 14th day. The total lipids of the albumen and yolk fractions did not change significantly until the 35th day of storage; at this time, the quality decreased significantly, indicating that the eggs were adequate for consumption until the 28th day. Considering the protein degradation profile and internal quality, Greater Rhea eggs can be stored for 21 days at 10 °C without alteration of their nutritional or functional characteristics.

Light dulls and darkens bird eggs.

Although egg color is generally consistent within individual birds and robust to environmental variation, recent evidence suggests a degree of susceptibility to environmental perturbation or modulation of egg color. Most of this variation manifests via the physiology of the laying female, but some direct impacts of the environment on laid eggs have also been discovered. Here we test whether light changes bird egg color and we quantify its effect, by subjecting variable blue-green eggs of Rüppell's weaver (Ploceus galbula) to a broad-spectrum light source under laboratory conditions, and measuring egg reflectance every few hours. Eggshells gradually decreased in reflectance across the entire measured wavelength spectrum of 250–800 nm. Reflectance peaks were disproportionately affected, such that the height decreased of both the blue-green peak and the smaller UV peak typical of blue-green eggs. The reflectance of lighter eggs was affected slightly more than that of darker eggs. These changes are similar to previous results for changes over long periods of time in darkness, suggesting that light might hasten the same process of pigment degradation that proceeds even without light. Comparison between the experimental light source and both sunlight and typical artificial lighting situations raises the possibility that significant color change might occur during incubation in some birds, but indicates that eggshell illumination in museums for short periods of study is unlikely to affect their color to a detectable extent. Additional research should be performed on eggs of other species and in other light environments, with an eye to an eventual generalized model of the effect of light on eggshell color.

Cold hardiness, adaptive strategies, and invasion of slugs of the genus Deroceras (Gastropoda, Pulmonata) in northeastern Asia

Abstract-Four species of slugs have been identified in the vicinity of Magadan: Deroceras laeve, D. altaicum, D. reticulatum, and D. agreste. They exemplify three different life cycle schemes, with D. reticulatum and D. altaicum wintering at the egg phase; D. laeve, at the slug phase; and D. agreste, at either phase. The D. altaicum and D. reticulatum slugs and D. laeve eggs are intolerant of subzero temperatures. D. laeve’s tolerate freezing and survive at temperatures below −28°C. The eggs of other species, which lose up to 35% of water upon cooling, can withstand temperatures as low as −15 to −17°C (D. altaicum), −25°C (D. agreste), and −35°C (D. reticulatum). According to preliminary data, D. agreste slugs survive at temperatures down to −10°C. The almost ubiquitous distribution of D. laeve in regions with cool summers (including zonal tundras) is accounted for not so much by the high rate of ontogeny as by its significant cold hardiness and ability to winter at different phases of the life cycle (except for the egg phase), which allows the period of development to be prolonged for the next seasons. The last is confirmed by the fact that the slugs collected before and after hibernation proved to have identical patterns of distribution by body weight. Three species of slugs introduced in the vicinity of Magadan fail to spread inland. In the case of D. reticulatum, this is explained primarily by the fact that the frost-free season in inland areas is too short to allow these slugs to complete ontogeny and lay eggs. The barriers to their expansion appear to be insuperable, since this process remains unsuccessful over no less than 75–80 years.

Polychlorinated dibenzo- p-dioxins and dibenzofurans in eggs of eight avian species from Dongting Lake, China

Concentrations of polychlorinated dibenzo- p-dioxins (PCDDs) and dibenzofurans (PCDFs) were determined in eggs of eight avian species collected from Dongting Lake of China to assess residue levels, accumulation patterns, and toxic potential in different avian species. Concentrations of total 2,3,7,8-substituted PCDD/Fs were in the range of 10.8–182 pg g −1 lipid weight. Eggs of great egret and lesser pied kingfisher contained higher levels of PCDD/Fs than eggs of other species, indicating the specific exposure and accumulation of PCDD/Fs relating to feeding habits and the life span. PCDD/Fs congener patterns varied among species. The patterns of PCDD/Fs in the eggs may be influenced by feeding habits, specific elimination, and metabolism. In general, concentrations of PCDDs were higher than those of PCDFs in avian eggs. On basis of lipid weight, total 2,3,7,8-TCDD toxic equivalents (TEQs) calculated based on the WHO TEFs for birds ranged from 2.04 to 42.0 pg g −1; and on basis of wet weight, total WHO-TEQs ranged from 0.19 to 1.59 pg g −1. 2,3,7,8-TCDF, 2,3,4,7,8-PeCDF, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD were the major contributors to TEQ concentration in most avian eggs, whereas 1,2,3,4,7,8-HxCDD also accounted for a major portion of TEQs in eggs of azure-winged magpie. Values of TEQs in avian eggs were lower than toxic threshold values, implying risk reduction and natural restoration of PCDD/Fs contamination in Dongting Lake region.

Measuring egg size using digital photography: testing Hoyt's method using Florida Scrub-Jay eggs

Egg volumes are most often estimated using a mathematical model that incorporates length and width measurements and a species-specific shape variable. Although adequate in many respects, this technique does not account for intraspecific variation in egg shape. We developed a computer-automated technique that uses calibrated digital photographs to render precise measurements of several egg-size parameters including length, width, volume, and surface area. The system extracts egg outlines from photographs, and divides each egg into latitudinal slices that are subsequently regarded as simple geometric shapes (cylinders or cone frustra) with volumes and surface areas that can be summed to generate size parameters for the entire egg. We tested this technique using 491 eggs from Florida Scrub-Jay (Aphelocoma coerulescens) nests and compared the resulting egg volumes with volumes calculated using the preeminent method of estimating volume from linear measurements. Our method was highly accurate, and differences between the volumes from our method and the alternative method were strongly associated with variation in egg shape. Advantages of our technique include decreased handling of eggs and increased accuracy. Software resources and additional information regarding the technique are available at http://www.archbold-station.org/abs/data/birddata/Bridge-JFO-eggsize.htm. SINOPSIS. Medidas de huevos utilizando fotograf´ ia digital: poniendo a pruebas el m´ etodo

Influence of prey on developmental performance, reproduction and prey consumption of Neoseiulus californicus (Acari: Phytoseiidae)

The Spical strain of the predatory mite Neoseiulus californicus (McGregor) is used as a biological control agent, but little is known about its preferred prey and host plants in Japan. Here we studied the development, reproduction and prey consumption of the Spical strain when fed on eggs of five different spider mite species deposited on both their laboratory-rearing plant and cherry, on which all five spider mite species developed well. The developmental periods of immature N. californicus females and males were significantly affected by the prey species they fed on, but not by the plants. No difference was found between males and females. The developmental period was shorter on eggs of two Tetranychus species than on eggs of Panonychus ulmi. Immature females had a higher predation rate than immature males. Preoviposition period, oviposition period and the number of eggs laid per female were not significantly affected by either the plants or the type of prey eggs. The postoviposition period and total adult longevity were shorter on eggs of P. ulmi than of the other four prey species, but there was no effect of plant substrate. The postoviposition period of the Spical strain was much longer than that of other N. californicus strains or other predatory mite species: the postoviposition period of the Spical strain was more than three times longer than the oviposition period, accounting for more than 75% of the total adult longevity. This suggests that the females need multiple mating to reach full egg load, but this remains to be tested. Total consumption by N. californicus adults was lower for eggs of P. ulmi than for eggs of the other four species, apparently because of the shorter postoviposition period when fed on eggs of P. ulmi. The intrinsic rates of natural increase (r(m)) on the rearing plant did not differ among prey species, whereas those on cherry were significantly different: the value was higher on Tetranychus urticae eggs than on eggs of other species. Only when N. californicus fed on T. urticae eggs, the r(m)-values were significantly different between the rearing plant and cherry (higher on cherry). Thus, the Spical strain of N. californicus could feed on eggs of all five spider mite species, deposited on a variety of plants with similar r(m)-values, suggesting that it could be successfully used to control spider mites in orchards and various crop fields of Japan.

Degradation of APCcdc20 and APCcdh1 substrates during the second meiotic division in mouse eggs

Metaphase II-arrested mouse eggs are stimulated to complete meiosis by sperm-induced Ca2+ spiking. The Ca2+ signal causes activation of the E3 ligase anaphase-promoting complex/cyclosome (APC), leading to the destruction of key proteins necessary for meiotic exit. We show, using western blots of mouse eggs, the presence of both APC activators cdc20 and cdh1, which target D-box and D-box/KEN-box substrates, respectively, for proteolysis. We decided to examine the temporal activation of APCcdc20 and APCcdh1 by coupling APC substrates to GFP and examining their destruction in real-time following release from second meiotic division arrest. D-box substrates were degraded quickly after the initiation of sperm-induced Ca2+ spiking, such that their degradation was complete by the time of second polar body extrusion. By contrast, KEN-box-containing substrates were degraded when CDK1 activity was low, during the period between polar body extrusion and pronucleus formation. This observation of apparent APCcdh1 activity in meiosis II based on destruction of exogenous GFP-coupled substrates was then confirmed by observing destruction of endogenous APCcdh1 substrates. These data are consistent with a model of initial APCcdc20 activation on sperm-induced activation, followed by APCcdh1 activation after second polar body extrusion. Interestingly, therefore, we propose that mammalian eggs undergo meiosis II with both APCcdc20 and APCcdh1, whereas eggs of other species so far described have APCcdc20 activity only.

The egg morphology of some species of Sennius Bridwell (Coleoptera: Chrysomelidae: Bruchinae) based on scanning electron micrographs

Eggs of Sennius crudelis Ribeiro-Costa & Reynaud, S. nappi Ribeiro-Costa & Reynaud and S. bondari (Pic) are described based on scanning electron micrographs and compared with eggs of other species of Bruchinae (Chrysomelidae).

Effect of intraguild predation on the survival and development of three species of aphidophagous ladybirds: consequences for invasive species

Abstract 1 Survival and development of hatchling larvae of three aphidophagous ladybirds (Coleoptera: Coccinellidae), Harmonia axyridis Pallas, Coccinella septempunctata brucki Mulsant and Adalia bipunctata Linnaeus, when fed their own and the other species eggs were recorded.2 In all three species, the larvae survived when fed conspecific eggs.3 The percentage of larvae of H. axyridis that survived decreased to 35% and 85% when fed eggs of A. bipunctata and C. s. brucki, respectively. All the larvae of A. bipunctata and C. s. brucki died after eating eggs of H. axyridis. None of the larvae of C. s. brucki died after eating eggs of A. bipunctata, whereas 46% of those of A. bipunctata died after eating eggs of C. s. brucki.4 In general, larvae were reluctant to eat the eggs of other species. However, larvae of C. s. brucki showed less reluctance than H. axyridis to eat the eggs of A. bipunctata.5 The consequence of this for invasive species of ladybird is discussed.

011.Waking up the egg. How the sperm regulates exit out of the meiotic cell cycle

A series of calcium spikes are induced in the mammalian egg cytoplasm at fertilisation. These calcium spikes, which last for several hours, are the necessary and sufficient signal that stimulates the egg to escape from arrest at metaphase of the second meiotic division. Metaphase arrest is achieved by preventing the destruction of cyclin B1, the regulatory component of Maturation (M-Phase) Promoting Factor, and securin, which prevents segregation of sister chromatids. Both these proteins are destroyed by tagging with ubiquitin, using an E3 ligase the Anaphase-Promoting Complex (APC). Ubiquitination tags them for proteolysis by the 26S proteasome. Work from my lab has demonstrated that the sperm calcium signal works through activating the APC, not the 26S proteasome. Although we do not know which APC component is affected by calcium, this activation appears specific to a metaphase-arrested cell cycle state. More recently we have found that the APC is differently regulated at specific points during exit from meiosis II. Before extrusion of the second polar body it is the APC activator cdc20 that regulates APC activity. However, following extrusion of the second polar body cdh1 appears the major regulator. It is probable, therefore, that the calcium spiking affects the activity of both APCcdc20 and APCcdh1. This swap in APC activator at the time of second polar body extrusion has not been reported in eggs of other species, in fact non-mammalian eggs all lack cdh1. Since APCcdc20 and APCcdh1 have different substrate specificities, the function of APCcdh1 in mammalian eggs warrants further investigation.

Effects of physiological condition and experience on oviposition behaviour of Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae) on eggs of Helicoverpa armigera Hübner (Lepidoptera: Noctuidae)

We produced an ethogram for and investigated effects of physiological condition and experience on oviposition behaviour for Trichogramma australicum on Helicoverpa armigera eggs. The data, coupled with the ethogram, have enabled the establishment of standard behavioural categories which can be used to assess acceptability of H. armigera eggs to T. australicum reared in vitro or in eggs of other species. Physiological and experiential conditions were investigated using females of three different ages (0–24, 24–48 and 48–72 h old), two types of sexual states (mated and unmated) and two types of ovipositional experience (naive and experienced). Durations of host finding, host examination, and post‐ovipositional re‐examination were reduced by oviposition experience and were shorter in younger females (0–48 h old). Oviposition experience reduces the duration of the drilling and percentage of females host‐feeding. Being mated and young reduces the host examination time in subsequent oviposition bouts. Only ovipositionally inexperienced females host‐feed before oviposition and host‐fed more frequently than experienced individuals after oviposition. Host‐feeding needs consideration for optimal culture.

Organochlorine pesticides in eggs of two waterbird species ( Fulica atra, Podiceps cristatus) from the same habitat: Reference site Lake Belau, Germany

Organochlorine (OC) residues were analyzed in eggs of Coot ( Fulica atra) and Great Crested Grebe ( Podiceps cristatus) from Lake Belau, North Germany. Concentrations were compared to concentrations in eggs of other species, and Lake Belau was suggested to be a relatively low contaminated reference area. Great variability could be measured between clutches of the same species but all eggs of Great Crested Grebe were significantly higher contaminated than eggs of Coot. Food contamination seems to be the major reason for the residues. The variability between clutches was greater than within the same clutch and no decreasing or increasing concentration in the sequentally laid eggs was obvious. Great Crested Grebes are better indicators for the contamination status of a lake.

Effects of chlorinated hydrocarbons on bald eagle chicks

Concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) were determined in eggs of eight avian species collected from Dongting Lake of China to assess residue levels, accumulation patterns, and toxic potential in different avian species. Concentrations of total 2,3,7,8-substituted PCDD/Fs were in the range of 10.8–182 pg g−1 lipid weight. Eggs of great egret and lesser pied kingfisher contained higher levels of PCDD/Fs than eggs of other species, indicating the specific exposure and accumulation of PCDD/Fs relating to feeding habits and the life span. PCDD/Fs congener patterns varied among species. The patterns of PCDD/Fs in the eggs may be influenced by feeding habits, specific elimination, and metabolism. In general, concentrations of PCDDs were higher than those of PCDFs in avian eggs. On basis of lipid weight, total 2,3,7,8-TCDD toxic equivalents (TEQs) calculated based on the WHO TEFs for birds ranged from 2.04 to 42.0 pg g−1; and on basis of wet weight, total WHO-TEQs ranged from 0.19 to 1.59 pg g−1. 2,3,7,8-TCDF, 2,3,4,7,8-PeCDF, 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD were the major contributors to TEQ concentration in most avian eggs, whereas 1,2,3,4,7,8-HxCDD also accounted for a major portion of TEQs in eggs of azure-winged magpie. Values of TEQs in avian eggs were lower than toxic threshold values, implying risk reduction and natural restoration of PCDD/Fs contamination in Dongting Lake region.

CuckooCuclus canorus parasitism onAcrocephalus Warblers in Southern Moravia in The Czech Republic

The Reed Warbler,Acrocephalus scirpaceus, in the Lednice area, Southern Moravia in the Czech Republic, was parasitized by the Cuckoo,Cuculus canorus, at a rate of at least 18.0 %. The Cuckoo eggs showed poor mimesis with the Reed Warbler eggs, but showed a greater resemblance to the eggs of other species breeding in the area, including the Great Reed Warbler,A. arundinaceus. This latter species was also parasitized, but we did not find enough nests to obtain a reliable estimate for the rate of parasitism. The parasitized Reed Warblers rejected the Cuckoo eggs at a high rate (42.1 %) and therefore both the hatching success and the breeding success of the Cuckoo was considerably lower than shown by comparable results from Britain. On the background of these results (poor mimesis of the Cuckoo eggs and a high rejection rate by the hosts) the question of the degree of specialization versus generalism in the Cuckoo's host preference is discussed.

Microbes Associated with Parthenogenesis in Wasps of the Genus Trichogramma

Cytological evidence is presented for a complete correlation between the presence of microorganisms in eggs and the incidence of revertible parthenogenesis (thelytoky) in wasps of the genus Trichogramma. A 2% lacmoid stain was used to visualize microorganisms in wasp eggs. Eggs of all 13 revertible parthenogenetic lines (i.e., lines that can be rendered bisexual by antibiotic treatment) carry microorganisms, while the eggs of all 5 nonrevertible parthenogenetic lines (i.e., lines that cannot be reverted to bisexual reproduction by either temperature or antibiotic treatment) are free of microorganisms. Microorganisms were not detected in eggs of 6 field-collected bisexual (arrhenotokous) lines, nor in those of 3 bisexual lines derived from revertible parthenogenetic lines by antibiotic treatment. The lacmoid stain provides a fast, easy method to detect microorganisms in the Trichogramma eggs and may be used in a modified form for the detection of microorganisms in the eggs of other species.