Number Of Eggs In Clutch Research Articles

Fate and effects of microplastic particles in a periphyton-grazer system

In the aquatic environment, microplastic particles (MP) can accumulate in microbial communities that cover submerged substrata, i.e. in periphyton. Despite periphyton being the essential food source for grazers in the benthic zones, MP transfer from periphyton to benthic biota and its ecotoxicological consequences are unknown. Therefore, in this study, we investigated the effects of 1) MP on embryonal development of freshwater gastropod Physa acuta embryos, 2) MP on adult Physa acuta individuals through dietary exposure and 3) on the MP surface properties. Embryonal development tests were carried out with spherical polyethylene MP in the size of 1–4 μm (MP). Over a period of 28 days, embryonal development and hatching rate were calculated. In the feeding experiments, periphyton was grown in the presence and absence of MP and was then offered to the adult Physa acuta for 42–152 h. The snails readily ingested and subsequently egested MP, together with the periphyton as shown by MP quantification in periphyton, snail soft body tissue and feces. No selective feeding behavior upon MP exposure was detected. The ingestion of MP had no effect on mortality, feeding and defecation rate. Yet, the reproductive output of snails, measured as the number of egg clutches and numbers of eggs per clutch, decreased after the ingestion of MPs, while the hatching success of snail embryos those parents were exposed remained unaffected. In contrast, hatching rate of snail embryos was significantly reduced upon direct MP exposure. MP optical properties were changed upon the incorporation into the periphyton and the passage through the digestive tract. Our results indicate that MP incorporated in periphyton are bioavailable to aquatic grazers, facilitating the introduction of MP into the food chain and having direct adverse effects on the grazers’ reproductive fitness.

Effects of Female and Male Density on their Mating Performance and Female Post-Mating Reproductive Fitness in Plagiodera versicolora (Laicharting) (Coleoptera: Chrysomelidae)

In insects, mating performance and female post-mating reproductive fitness is closely related to female and male density. In nature, females and males of the willow leaf beetle, Plagiodera versicolora (Laicharting), exhibit the phenomenon of swarming damage. This study investigated the effects of female and male density on their mating performance and on female post-mating fecundity, egg hatching rates, and egg-laying patterns. Female and male density had a significant positive effect on the time from pairing to successful mating and on female fecundity, the duration of the egg-laying period, and the number of egg clutches, but it had a significant negative effect on the egg hatching rate. Female and male density had no significant effect on female post-mating longevity and the number of eggs per clutch. Our study shows that variation in female fecundity and egg-laying patterns is an adaptive strategy for P. versicolora at relatively high population densities. This strategy helps to expand the distribution of offspring and lower the competition for food resources among offspring, which, in turn, helps to maintain or increase population abundance.

Reproduction of the Roman snail (Helix pomatia L.) from a local natural population in farm conditions and in a natural habitat

Abstract The aim of this study was to compare the quality of clutches and reproduction results of two groups of Roman snails (Helix pomatia) from the same local population, laying eggs simultaneously in semi-natural farm conditions and in a natural habitat. The study material were Roman snails aged 2 or more years which had entered the third phenological season of their life and thus the first season of sexual maturity. Observations were conducted at an earthen enclosure in a greenhouse belonging to the experimental farm for edible snails at the National Research Institute of Animal Reproduction in Balice near Kraków (Poland) as well as at a site where a local population naturally occurs in the uncultivated park surrounding the Radziwiłł Palace. In the June-July season, differences among such parameters as weight of clutch, number of eggs in clutch, mean egg weight, and hatchling percentage when compared to the total number of eggs in the clutch were compared. It was determined that clutches of eggs from the natural population laid in the greenhouse were of lesser weight (P<0.01), contained fewer eggs (P<0.05), and the mean weight of individual eggs was less (P<0.05) than in clutches laid simultaneously in a natural habitat. Both in the greenhouse and the natural habitat, in the first phase of laying eggs (June) the weight of the clutch and number of eggs its contained were greater than in the second phase (July). However, only for snails laying eggs in the greenhouse were these differences statistically significant (P<0.05) and highly significant (P<0.01), respectively. Statistically significant differences were not observed in hatchling percentage between eggs laid in the greenhouse and the natural habitat. The lower number of eggs laid in the farmed conditions of the greenhouse was successfully compensated for by the absence of mass destruction by rodents which occurred in the natural habitat.

Evaluation of the hazard of irregularly-shaped co-polyamide microplastics on the freshwater non-biting midge Chironomus riparius through its life cycle.

Plastics pollution is increasingly attracting societal and political attention. However, despite extensive research effort recently dedicated to the hazard of plastics in the environment, the data obtained are often redundant and essential knowledge gaps exist: available freshwater ecotoxicity data mostly concern Daphnia magna and are derived from acute exposure to spherical particles. In this paper, we address this gap by exploring the biological effects of irregularly-shaped co-polyamide (PA, 10-180μm) on Chironomus riparius - a very versatile organism that during its life-stages inhabits both sediment and water column - relevant compartments for microplastics (MP) pollution. C.riparius represents an important part of the freshwater food chain and is also a standard OECD test organism. Different toxicity endpoints along the life cycle of C.riparius (28 days) were used as described in OECD 218: emergence, time to emergence, sex ratio of imagoes and the number of egg clutches per female. Chironomid larvae were exposed to 100mgPA kg-1 (i.e., 10,100 particles kg-1) sediment throughout. Soluble Zn-salt (1mg Zn L-1) was used as a positive control and as a co-pollutant in combination with PA. We demonstrated that the tested concentrations of PA and Zn alone as well in combination showed no adverse effects for C.riparius in chronic exposures. 100mgPA kg-1 also did not affect the life cycle traits of the offspring of PA-exposed parent Chironomids. The data obtained will be useful for environmental risk assessment of PA when actual environmental concentrations of PA will be available.

Assessing the Impacts of Methoxychlor Exposure on the Viability, Reproduction, and Locomotor Behavior of the Seminole Ramshorn Snail (Planorbella duryi).

In the present study, the effects of short-term methoxychlor exposure on the viability, reproduction, and locomotor behavior of adult seminole ramshorn snails (Planorbella duryi) was assessed. To examine impacts on viability and behavior, individuals were exposed to a water control, vehicle control, or 12.5, 50, 100, 250, 500, or 1000 μg/L of methoxychlor for 48 h; and differences in mortality and locomotor behavior assessed using the freely available ToxTrac software. To determine impacts on reproduction, pairs of snails were exposed to a vehicle control and 12.5, 25, 50, 100, and 250 μg/L of methoxychlor for 9 d; and the number of clutches and eggs laid quantified every 24 h. Methoxychlor concentrations in treatments were determined using gas chromatography. Complete mortality was observed in the 500 μg/L and 1000 μg/L treatments after 48 h and in the 250 μg/L treatment after 9 d. Decreases in the number of egg clutches were observed in all treatments, and the number of eggs laid decreased starting in the 25 μg/L treatment. Decreases in average speed, mobile speed, and total distance traveled, as well as a significant increase in frozen events, were also observed. Our results suggest that methoxychlor exposure causes detrimental effects on several nonlethal endpoints in a nonmodel aquatic invertebrate species and that the analysis of locomotor behaviors serves as a reliable, sensitive endpoint for ecotoxicology testing. Environ Toxicol Chem 2019;39:220-228. © 2019 SETAC.

Development of Black Soldier Fly, Hermetia illucens (Diptera: Stratiomyidae) in Selected Organic Market Waste Fractions in Accra, Ghana

Aims: To assess the effect of organic waste and their formulations on the development of the black soldier fly larvae. Study Design: The experiment used one time feeding (lump feeding) of feedstocks obtained from organic market waste fractions and their combinations. The arrangement of composting containers followed a Randomized Complete Block Design (RCBD), replicated three times. Place and Duration of Study: The study took 3 months and was conducted at the BSF laboratory of the Soil and Environmental Science Research Centre, Biotechnology and Nuclear Agriculture Research Institute of the Ghana Atomic Energy Commission in Accra, Ghana, West Africa. Methodology: Two hundred and forty (240) hand counted 5 day old BSF larvae were inoculated onto 2 kg each of organic market waste fractions and their combinations in 60 L plastic containers covered with a mesh. Equal quantities of the above feedstock without larvae served as control. The arrangement of the containers followed a Randomized Complete Block Design (RCBD), replicated three times. Moisture content, larval growth parameters, temperature, relative humidity, prepupal development were recorded. Results: Whiles moisture contents of most of the feedstock decreased gradually over the trial period, that of fruit waste only, fruit waste + corn husk and fruit waste + vegetable waste increased with time and was higher at the end of the trial than at the beginning. Composting temperature in all the feed stocks never reached the thermophilic stage and was between 29 – 38°C. The lowest temperature of 28.88°C was recorded in the mixture of vegetable waste and fruit waste whiles the highest, 37.55°C was recorded in the mixture of corn husk and uncooked food waste compost. Composting humidity ranged between 59 and 87% with significant differences being observed across treatments on days 0, 10, 15, 20 and 25. Larvae reared on a mixture of all the feedstock was significantly the heaviest (176.66 mg). Significant differences were observed in larval length and those fed with a mixture of fruit waste and uncooked food waste were the longest (17.66 mm). A highly significant number of eclosed adults, number of females and the number of egg clutches were observed among treatments. Conclusions: Vegetable waste only, fruit waste only and a combination of vegetable waste + uncooked food waste; fruit waste +uncooked food waste; and a combination of all the wastes were the most preferred organic waste as they produced the optimum larval characteristics. The composting bins should be fitted with an outlet for leachates from the compost to drain out to avoid increase in compost moisture which will create anaerobic conditions that might delay compost maturity.

Reproductive ecology of the glass frog Espadarana prosoblepon (Anura: Centrolenidae) in an urban forest of the Central Andes of Colombia

ABSTRACTPopulation and reproductive behaviour aspects of the glass frog Espadarana prosoblepon are well known for populations from Central America, but similar information is lacking for populations from South America. We recorded the reproductive ecology of a population of the glass frog E. prosoblepon in the city of Armenia, Central Andes of Colombia. With weekly surveys with mark-recapture between December 2013 and November 2015, we monitored activity patterns and evaluated if the probability of males mating is associated to their body size or to chorus tenure (i.e. the number of nights a same individual is calling for attracting a mate). In addition, upon observing an amplexus, we recorded the behaviour of the individuals until oviposition and noted characteristics of egg clutch. We recorded 47 males and 32 females, nine amplexus events, eight ovipositions, and 21 egg clutches (35.4 ± 4.79 eggs per clutch, N = 29). Activity of males and females and the number of egg clutches were positively correlated to rainfall. Mating success of males was not associated to their body size, but it was positively associated to longer chorus tenure; clutches from large females had a higher number of eggs than clutches from small females. Oviposition occurred on average 3.76 ± 1.74 hours after we first observed the amplexus, occurring 93.1% of the time in fronds of Selaginella geniculata at an average height of 1.58 ± 0.44 m. After the oviposition, the male left the site, while the female remained between 30 and 45 min, partially covering the eggs. The reproductive behaviour of E. prosoblepon did not vary widely between a population in Costa Rica and our population in time to oviposition, and mating success of males associated to chorus tenure; however, in our study population we recorded a larger clutch size and the preference for S. geniculata fronds as oviposition substrate.

Effect of adult population density on egg production in the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae)

The black soldier fly is economically important because its prepupae are used as feed for many animals, including fish and swine. In Korea, black-soldier-fly farms have attempted to increase annual breeding and mass egg production for use in animal feed, as well as the decomposition of organic waste. Such efforts require an understanding of optimal mating and oviposition techniques. Specifically, adult densities and cage size may both improve the efficiency of mass egg production. Our study used four sizes of nylon cages (<TEX>$1.0{\times}1.0{\times}2.5m$</TEX>, <TEX>$1.5{\times}1.5{\times}2.5m$</TEX>, <TEX>$2.0{\times}2.0{\times}2.5m$</TEX>, <TEX>$2.5{\times}2.5{\times}2.5m$</TEX>) and three density treatments (4 kg, 8 kg, and 10 kg of pupae) to investigate optimal habitat size and adult density. We found that cage size (independent of density) did not significantly influence female fecundity (number of egg clutches and egg weight), whereas higher densities increased egg number and weight regardless of cage size. Thus, we recommend manipulating adult density to enhance productivity in commercial black-soldier-fly farming. However, we also propose further detailed research to develop methods that account for seasonal changes and environmental conditions, as climatic variables (temperature, sunlight) likely influence female fecundity as well.

Reproduction in the Baja California Collared Lizard, Crotaphytus vestigium (Squamata: Crotaphytidae)

Crotaphytus vestigium, a rock-dwelling species of the peninsular ranges of Baja California, occurs along the northern slope of the San Jacinto Mountains, Riverside County, California, south to the southern margin of the volcanic Magdalena Plain in Baja California Sur (McGuire 1996). Published information on the reproduction of C. vestigium consists of brief accounts by Lemm (2006), Ivanyi, (2009) and field observations by McGuire (1996), Grismer (2002) and Stebbins (2003). The purpose of this paper is to examine the reproductive biology of C. vestigium from a histological analysis of gonadal material from museum specimens, an often used method, see for example, Goldberg (1974). Information on the reproductive cycle such as timing of spermiogenesis, number of egg clutches produced and period of vitellogenesis may not only be helpful in determining phylogenetic affinities, but also provides essential life history data for implementing conservation management strategies of lizard species. We examined 61 C. vestigium consisting of 33 males (mean snout-vent length, SVL 5 96.5 mm 6 12.3 SD, range: 72–116 mm and 28 females (mean SVL 5 80.4 mm 6 8.6 SD, range: 54–93 mm) from Imperial, Riverside and San Diego Counties, California and Baja California and Baja California Sur, Mexico. Specimens were examined from the herpetology collections of the Natural History Museum of Los Angeles County (LACM), Museum of Vertebrate Zoology (MVZ), and San Diego Society of Natural History (SDSNH) (Appendix I). Lizards were collected 1934–1997. Histology slides were deposited at LACM, MVZ and SDSNH. The left testis was removed from males and the left ovary was removed from females for histological examination (Presnell and Schreibman 1997). Enlarged ovarian follicles (. 5 mm) and/or oviductal eggs were counted. Tissues were embedded in paraffin, sectioned at 5 mm and stained with hematoxylin followed by eosin counterstain. Ovary slides were examined for yolk deposition or corpora lutea. Testis slides were examined to ascertain the stage of the testicular cycle present. Mean SVL of male and female C. vestigium were compared using an unpaired t-test (Instat vers. 3.0b, Graphpad Software, San Diego, CA). The mean male SVL of C. vestigium significantly exceeded that of females (unpaired t test, t 5 5.82, df 5 59, P , 0.0001). Monthly stages in the testicular cycle of C. vestigium were shown in Table 1. Three stages were present: (1) Regression, the germinal epithelium was reduced to 1–3 cell layers in thickness and consists of spermatogonia and Sertoli cells; (2) Recrudescence, a proliferation of germ cells for the next period of sperm formation was underway. In early recrudescence, primary spermatocytes predominate, Bull. Southern California Acad. Sci. 109(3), 2010, pp. 153–156 E Southern California Academy of Sciences, 2010

Effects of Photoperiod on Reproduction and Longevity ofPodisus nigrispinus(Heteroptera: Pentatomidae)

AbstractEffects of photoperiod on reproduction and longevity of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae) were assessed under seven different photophases (10, 11, 12, 13, 14, 15, and 16 h) at a constant 28 ± 1°C temperature and 70 ± 10% RH in the laboratory. Photoperiod affected the longevity of P.nigrispinus females. The highest longevity (24.10 d) occurred with a 15-h photoperiod, compared with longevity of 9.75 d at 12-h photoperiod. The preoviposition period of P.nigrispinus was influenced by the photoperiod. The preoviposition period of P.nigrispinus was longer for the 16-h photoperiod (7.25d) than for the 12- (4.06d), 13- (4.00 d), and 14-h (3.68d) photoperiod. The postoviposition period, the number of egg clutches per female per day, and the interval between egg clutches were not affected by the photoperiod. The postoviposition period ranged from 1.46 d (at 14 h of light) to 3.71 d (at 11 h of light). The number of egg clutches per female per day varied between 0.19 (at 11 h or 14 h of light) and 0.40 (at 15 h of light). The interval between egg clutches ranged from 1.29 d (at 14 h of light) to 2.07 d (at 11 h of light). The variation in the number of eggs and egg clutches per female of P.nigrispinus in relation to their age varied according to the photophase to which they were exposed. The fecundity of P.nigrispinus females was higher in 15 h of light. These informations serve as a valuable ecological variable in modeling population dynamics of P.nigripinus, both in the field and in the laboratory, thereby contributing to the success of A.argillacea control programs.

The influence of fennel feeding on development, survival, and reproduction in Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae)

The aim of this study was to determine the effectiveness of fennel (Foeniculum vulgare Mill.) leaves as food on development, survival, and reproduction in Podisus nigrispinus (Dallas). Newly hatched P. nigrispinus nymphs were used in this study. The prey consisted of 3rd-instar Alabama argillacea (Huebner) larvae. Fennel and cotton leaves were not sufficient to enable the full development of the predator to its adult stage. It was verified that 35% of the nymphs that fed on cotton leaves and water, and 31% of the nymphs that fed on fennel leaves and water completed their 2nd instar in 5.68 days and 6.30 days, respectively, while nymphs from the 1st instar that had a water diet did not complete their 2nd instar and achieved 4.12 days of longevity. The high fecundity in the P. nigrispinus females fed fennel or cotton leaves was mainly due to an increase in the number of egg clutches per female, which resulted in greater egg production, when compared to females that did not have plants in their diet. Phytophagy could make P. nigrispinus an efficient agent for the biological control in intercropping systems of cotton with fennel.

Effect of vegetation density, height, and connectivity on the oviposition pattern of the leaf beetle Galeruca tanaceti

AbstractVegetation structure can profoundly influence patterns of abundance, distribution, and reproduction of herbivorous insects and their susceptibility to natural enemies. The three main structural traits of herbaceous vegetation are density, height, and connectivity. This study determined the herbivore response to each of these three parameters by analysing oviposition patterns in the field and studying the underlying mechanisms in laboratory bioassays. The generalist leaf beetle, Galeruca tanaceti L. (Coleoptera: Chrysomelidae), preferentially deposits its egg clutches on non‐host plants such as grasses. Earlier studies revealed that oviposition within structurally complex vegetation reduces the risk of egg parasitism. Consequently, leaf beetle females should prefer patches with dense, tall, or connected vegetation for oviposition in order to increase their reproductive success. In the present study, we tested the following three hypotheses on the effect of stem density, height, and connectivity on oviposition: (1) Within habitats, the number of egg clutches in areas with high stem densities is disproportionately higher than in low‐density areas. The number of egg clutches on (2) tall stems or (3) in vegetation with high connectivity is higher than expected for a random distribution. In the field, stem density and height were positively correlated with egg clutch presence. Moreover, a disproportionately high presence of egg clutches was determined in patches with high stem densities. Stem height had a positive influence on oviposition, also in a laboratory two‐choice bioassay, whereas stem density and connectivity did not affect oviposition preferences in the laboratory. Therefore, stem height and, potentially, density, but not connectivity, seem to trigger oviposition site selection of the herbivore. This study made evident that certain, but not all traits of the vegetation structure can impose a strong influence on oviposition patterns of herbivorous insects. The results were finally compared with data on the movement patterns of the specialised egg parasitoid of the herbivore in comparable types of vegetation structure.

Laying Characteristics of One- and Two-year Old Pheasants (Phasianus colchicus, L.)

The aim ofthe study was to assess laying traits, the weight of eggs and characters ofthe laying rhythm of pheasants in the first and second years of reproduction. Pheasants (10 cockerels and 50 hens) were kept in aviaries. Daily, individual control of laying was performed beginning with the day of the first laying and ending with the last egg. The following parameters were evaluated: age at first laying, length of the laying period, number of laid eggs and the average weight of the egg in the 8th week of laying. The laying rhythm was also assessed and comprised: the number of egg clutches, the number of eggs in a clutch, the number of eggs in the longest clutch, the number of intervals, the length of intervals and the longest interval between clutches. During the first period of reproduction, in comparison with the second, pheasants laid slightly more eggs of similar average weight. The first laying period was longer than the second and was characterised by a greater number of egg clutches and greater number of intervals between clutches. The greatest number of eggs was laid in 10-egg and longer clutches, although the l-egg clutches were the most numerous. A positive correlation was found between the number of eggs and the number of clutches, the greatest number of eggs in a clutch and the number of intervals between clutches. The similar values of the reproductive characters of one- and two-year old pheasants point to the possibility of longer utilization of these birds than only for one laying period. On the other hand, the considerable variability between the experimental hens with regard to the number and the length of egg clutches, as well as the intervals between them, indicate the possibility to carry out selection taking into account traits characterising the laying rhythm.

Analysis of the Laying Rhythm and Reproductive Traits of Geese

The aim of the performed investigations was to analyse the laying rhythm and reproductive traits of Kołuda white geese from the W11 reproduction strain and to determine the heritability of these traits as well as correlations between the laying rhythm traits and reproductive traits. The total number of geese participating in the experiment included 383 one-year old layers from the control flock (the first year of reproductive utilisation). The following traits characterizing the laying rhythm were assessed individually for each layer: the number of 2 and 3-egg clutches or more, length (in days) of 2- or more egg clutches as well as the length of intervals between the laid eggs during the entire laying period. The following reproductive traits were also assessed individually for each bird: age at sexual maturity, initial number of eggs (eggs laid during the period from January, 1st to April, 30th), number of eggs during the whole laying period, laying intensity (the total number of eggs x 100/length of the laying period in days) as well as the length of the reproductive period. It was found that Kołuda white geese laid most of their eggs (on average 70.2%) singly and not in clutches. With regard to egg clutches, it was found that 2-egg clutches constituted 85.3% of eggs laid in clutches. Moderate or high variability of traits associated with the laying rhythm and reproduction were demonstrated. The observed moderate heritability of the laying rhythm traits indicate that they may be utilised in the selection programs for geese. On the other hand, the reported high, positive genetic correlation coefficients between the number of egg clutches and the initial and total egg number as well as laying intensity confirm the existence of interactions between these traits. This fact may be helpful in breeding programs for determining the optimal selection systems for geese.

Does a Polyphagous Predator Prefer Prey Species That Confer Reproductive Advantage?: Case Study ofPodisus maculiventris

The purpose of this study was to determine whether preferred prey of Podisus macu- liventris (Say) (Heteroptera: Pentatomidae) adult females also conferred maximal fecundity. We also studied egg development and maturation as a function of predator age, i.e., ovigeny as used predominantly in the context of parasitoids. To determine prey preference, adult females were simultaneously offered Þve pest prey: 1) beet armyworm, Spodoptera exigua (Hubner) (Lepidoptera: Noctuidae); 2) fall armyworm, Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae); 3) cabbage looper, Trichoplusia ni (Hubner) (Lepidoptera: Noctuidae); 4) greater wax moth, Galleria mellonella (L.) (Lepidoptera: Pyralidae); and 5) yellow mealworm, Tenebrio molitor (L.) (Coleoptera: Tenebrionidae) (n 20). In a second experiment, adult P.maculiventris females were provided a single species of prey (for each of the Þve prey species, n 10). This experiment was repeated over four durations: 7, 15, 22, and 30d. After each time trial, egg load dissections were performed, and numbers of mature and immature eggs were recorded. P. maculiventris displayed a preference of beet army- worm, whether measured as numbers attacked or estimated biomass consumed. However, no signif- icant differences were found in cumulative numbers of eggs laid under the different prey treatments, with the exception of the 22-d trial where signiÞcantly more eggs were laid when feeding on the cabbage looper. During the 22-d trial, the number of egg clutches and numbers of eggs per clutch were highest when fed cabbage looper and lowest with yellow mealworm. Percentage of egg hatch combined across time trials was highest in cabbage looper (81.7%) and lowest in greater wax moth (63.8%). Egg load dissections revealed that the total number of eggs and numbers of mature eggs declined signiÞcantly with predator age. However, numbers of immature eggs increased. The mean number of mature eggs in 7-d-old predators represented only 5% of mean cumulative numbers of eggs laid by 30-d-old predators, indicating that P. maculiventris is strongly synovigenic, where egg development and maturation continues during adulthood. The implications of these results are discussed from the context of P. maculiventris as a biological control agent.

Population Responses and Food Consumption by PredatorsColeomegilla maculataandHarmonia axyridis(Coleoptera: Coccinellidae) During Anthesis in an Illinois Cornfield

We monitored numbers of Coleomegilla maculata DeGeer and Harmonia axyridis (Pallas) eggs, larvae, and adults in an Illinois cornfield during anthesis. Larvae and adults were collected from the field and their gut contents were examined. Also, daily pollen deposition was recorded over the sample period, and prey biomass per plant was calculated for each of four replicate plots of field corn. The numbers of egg clutches and adults per plant were compared with daily pollen deposition, and pre- and postanthesis daily pollen deposition, densities of egg clutches, and adult densities were compared. Also, we compared the numbers of larvae and adults collected per plot and pollen and prey densities in the plots. Finally, the proportions of larvae and adults that had fed on corn pollen or prey were compared between predator species. We found that the number of coccinellid egg clutches increased significantly after anthesis and that the densities of adults of both species were not significantly different pre- and postanthesis. Larval and adult populations of H. axyridis were significantly correlated with prey densities, but C. maculata were not. All instars of C. maculata and H. axyridis occurred in corn during anthesis, and corn pollen was found in the guts of all four instars and in adults of both species. Dissections revealed that the majority of C. maculata larvae and adults had pollen in their guts, and a minority of H. axyridis larvae and a single adult had pollen in their guts. Conversely, the majority of H. axyridis larvae and adults had insect prey in their guts, and <40% of C. maculata larvae and adults had prey in their guts. Potential mechanisms for the numerical increases of coccinellids observed during anthesis and the implications of pollen feeding for risk assessment of transgenic insecticidal corn to C. maculata are discussed.

Effects of plant feeding on the development, survival and reproduction of Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae)

Diets consisting of leaves of cotton and/or water were insufficient to promote the complete development and survival of Podisus nigrispinus (Dallas) to the adult stage. However, nymphs fed leaves lived longer than those provided with only water. Addition of Alabama argillacea (Huebner) larvae to the diet of P. nigrispinus added a substantial increment to the survival during the nymphal stage. The addition of cotton leaves to the diet of P. nigrispinus nymphs promoted an increase in the weight of newly eclosed adults, independent of predator sex. In addition, diets supplemented with cotton leaves promoted an increase in the duration of the oviposition period, the number of egg clutches per female, and the number of eggs per female. No effects were noted on either the duration of the pre-oviposition period, the number of eggs of the first clutch, the number of eggs per clutch, the interval between egg clutches, or sex ratio. Feeding on plant material by P. nigrispinus is a potentially positive attribute in biological control against cotton leafworm.

Nesting of Grey Heron (Ardea cinerea L.) on Sea Islands of South Primorye

The nesting of Grey Heron (Ardea cinerea L.) on rocks of sea islands of the Great Peter's Bay was observed periodically from 1969. There are the following three colonies, being numbered (in 1982) 630 pairs on Furugelm Island, 23 pairs on the of Gildebrandt Is. and 69 pairs on a small rock off Butakov Cape. The colony of Furugelm Is. increased in number approximately by 10 times from 1969 to 1982 most of all due to establishment of Marine State Reserve in 1980. Evidently, heronries on islands appeared not long ago, migrating here from the continental coast. This species arrives in south Primorye in middle March, egg laying in the insular colonies in the first half of April, chicks appear in the first half of May and nests are left in early July. Most nests are built just on rock ledges or on the ground; material for nests used (n=8) consists of Chenopodium sp. (57.8%) and Artemisia sp. (32.1%). An average number of eggs in clutch, was 3.4 (n=26) in 1972 and 3 (n=25) in 1979; number of fledglings (average) was 1.33 (n=15) in 1980. Behavior of chicks at the age of more than one month is characterized specific features connected with the terrestrial location of nests allowing to move lightly within the heronry in any direction. They taken away food in chicks from other broods (about 15 chicks gather around the bird with food); cases of kill of the youngest ones by oldest both in their own brood and from the others are common, aggressiveness of chicks increase in time of feeding; one case of cannibalism was observed when a fledgling ate two chicks from the neighbouring nest. A main reason of mortality is a slaughter of the youngest chicks by eldest; chicks from the late broods survive rarely being killed from trauma or hunger. Herons forage on the continent. A distance from colonies to feeding grounds ranges from 10 to 35km. Chicks are basically fed with the following fishes occurring in brackish and freshwater reservoirs: Carassius auratus, Phoxinus lagowskii, Leuciskus brandtii, Gasterosteus aculeatus, Hyporhamphus sajori and Gymnogobius macrognatus.

Life History and Bionomics of Two American Species of Fowl Ticks (Ixodoidea, Argasidae, Argas) of the Subgenus Persicargas

The life cycles of Argas ( Persicargas ) radiatus Railliet and A. (P.) sanchezi Duges are about equal in length, requiring about 2 months, with a minimum of 6 weeks. Temperature sensitivity limits sanchezi to 2–3 generations per year because reproduction is inhibited at 25°C or lower. In south Texas, radiatus could have an many as 5 generations per year. The characteristic of Persicargas spp. to have an additional nymphal stage (N3) is discussed. The ability of females of each species to produce up to 6 clutches of viable eggs following 1 insemination by the male is demonstrated. The maximum number of egg clutches was 8, and 1 female radiatus produced 1185 eggs during her reproductive life. Under laboratory conditions, 1 female radiatus survived unfed for 39 months and 1 field-collected female allowed to engorge several times survived for at least 40 months. Attempted crossings of the 2 species with each other and each with A. (P.) persicus (Oken) indicate all 3 species are biologically distinct.