Toxicity of Acalypha indica (Euphorbiaceae) and Achyranthes aspera (Amaranthaceae) leaf extracts to Aedes aegypti (Diptera: Culicidae)

Alternative control strategies for the dengue vector Aedes aegypti L. (Diptera: Culicidae) include botanical insecticides. They are believed to pose little threat to the environment or to human health and may provide practical substitutes for synthetic insecticides. In this study, we determined the biological activities of methanol extracts of Acalypha indica L. (Euphorbiaceae) and Achyranthes aspera L (Amaranthaceae) leaves individually and in combination as botanical insecticides against Ae. aegypti. Based on LC₅₀ values for 4th instar Ae. aegypti, the combined extracts showed the strongest larvicidal activity (277 ppm). A. aspera and A. indica extracts individually gave similar results (409 and 420 ppm, respectively). Respective LC₅₀ values for pupae were 326 ppm, 456 ppm, and 467 ppm. In studies of smoke toxicity, 64% of females exposed to negative control smoke (no extract) blood fed on chicken, whereas 17% blood fed when exposed to smoke containing A. aspera extract and to positive control smoke (0.2% d-allethrin). In the field, treatment of water storage tanks (≈ 0.5 m³) with combined plant extract reduced larval and pupal populations by 97% and 81%, respectively, after 5 days. Given the results of this study, further evaluation of the combined (A. indica + A. aspera) extract as a mosquito larvicide is warranted. Mosquito coils with A. aspera extract also show promise as a practical and potentially economical means for mitigating mosquito blood feeding.     

Changes in the swimming behavior of Pseudodiaptomus annandalei (Copepoda,Calanoida) adults exposed to the diatom toxin 2-trans, 4-trans decadienal

Diatoms are broadly present in marine habitats and often dominate seasonal phytoplankton blooms in polar and temperate latitudes. Certain species produce polyunsaturated aldehydes upon mechanical wounding caused by mesozooplankton grazing. Ample evidence is available on toxin-induced reproductive failure in copepods, yet their behavioral effects remain unclear. Here we present results of laboratory experiments in which we investigated the immediate effects of the diatom-derived aldehyde 2-trans, 4-trans decadienal on the three-dimensional swimming behavior of the calanoid copepod Pseudodiaptomus annandalei. Short-term direct exposure to the toxin at 3 μM, 6 μM and 12 μM induced hyperactivity in the three adult states, as evidenced by a marked and dose-dependent increase in the number of trajectories. It also caused a higher proportion of vertical movements. In males and ovigerous females exposed to decadienal at 3 μM and 6 μM, hyperactivity came with an equally specific dose-dependent decrease in swimming speed. Males and ovigerous females swam faster at 12 μM than at 6 μM, suggesting a complex mode of action of the toxin. In non-ovigerous females, decadienal had little effects on swimming speed, supporting the assumption that female copepods are less affected by certain environmental stressors. Multifractal analysis revealed differences in the statistical properties of the swimming behavior between experimental conditions. The moment structure function of the displacement appeared to be moderately multifractal in the three adult states swimming in control water. Ethanol as carrier solvent at 200 ppm caused an increase in swimming speed and a switch toward a more ballistic motion in males and ovigerous females. On the opposite, exposure to the toxin reduced or cancelled the effects of ethanol and resulted in a more Brownian motion for high moment values. Decadienal had little effects on the behavior of non-ovigerous females except at the highest concentration. Our results demonstrate that decadienal, a model diatom aldehyde, impairs the behavior of adult copepods. They provide further information on the interaction between diatoms and their main predator.     

Temperature effects on embryonic development of Paratlanticus ussuriensis (Orthoptera: Tettigoniidae) in relation to its prolonged diapause

Paratlanticus ussuriensis eggs overwinter by entering diapause, which can be prolonged to more than 1 year depending on environmental conditions. To determine temperature effects on diapause duration of P. ussuriensis eggs, the rates of embryonic development and hatching were compared at various temperatures conditions by measuring embryonic stages and egg weights. Most eggs stayed in a very young stage (blastoderm formation, stage 4) when reared at 15 and 20 °C, 10–30% eggs developed into middle or late stages when reared at 25 °C, and most embryos developed fully (stage 23/24) when reared at 30 °C. Egg weight at 30 °C was 1.5 times higher than those reared at 20 °C. Chilling induced hatching in embryos at stage 23/24. Chilling caused stage 4 embryos to develop into stage 24, but they failed to hatch in response to a second warm period. Thus, P. ussuriensis eggs can overwinter either as young embryos (initial diapause) or as fully-developed embryos (final diapause). Eggs that experience an initial diapause overwinter again the second year in a final stage diapause. The post-diapause period was shorter when embryos overwintered in a final stage diapause. The hatching rate was highest in a temperature range of 7.5–15 °C. Our results suggest that temperature is an important environmental factor for the control of prolonged diapause in P. ussuriensis and initial diapause plays an important role in the control of its life cycle.     

Does the hydric environment affect the incubation of small rigid-shelled turtle eggs?

Hydric environments are hypothesized to have minor effects on the embryonic development of rigid-shelled turtle eggs due to the low water permeability of the eggshell. However, the water reserve in the eggs may still influence their resistance to environmentally induced dehydration. We incubated rigid-shelled turtle eggs (Pelodiscus sinensis) on different moist substrates (from ? 12 to ? 750 kPa) to test the hypothesis that small rigid-shelled eggs would be sensitive to hydric environments. The hydric treatment significantly affected the incubation period, with eggs incubated in the moistest and driest substrates taking longer to hatch than those on the medium-moisture substrates. Hatching success was slightly lower for eggs incubated in dry conditions than those in wet conditions, but the difference was not statistically significant. The heart rates of early embryos were lower on moist substrates than those on dry substrates, but this difference disappeared in late embryos. Hatchlings from the moistest substrate were larger (in carapace length and width) and heavier than those from drier substrates. However, the dry body mass of the hatchlings did not differ among the hydric treatments. The functional performance (righting response) of the hatchlings was affected by the hydric environment. The time to right was shorter for the hatchlings from the substrate of ? 12 kPa than those from ? 220 kPa. These results are consistent with the hypothesis that the hydric environment may significantly affect developing embryos and the resulting hatchlings in turtle species, such as P. sinensis, with small rigid-shelled eggs.     

Female reproductive pattern of Callinectes sapidus Rathbun, 1896 (Brachyura: Portunidae) in Iskenderun Bay,Eastern Mediterranean

We studied the female reproductive pattern of Callinectes sapidus, which was introduced to the Mediterranean in the 20^th century. We assessed female size at first maturity, fecundity, and fecundity relationship to size in Iskenderun Bay, eastern Mediterranean, Turkey. Samples were collected between July 2014 and June 2015 using bottom trawling at depths ranging from 1 to 50 m. A total of 322 crabs were caught of which 308 (95.7%) were females including 116 ovigerous ones. The minimum carapace width of the mature females was 39.1 mm and the mean carapace width 123.8 mm. The carapace width of ovigerous females varied between 95.1 and 144.5 mm, with a mean of 120.3 mm. The highest number of ovigerous females was observed in July and August. Mean fecundity was 1.91 million (667,950–4,669,853) eggs per female. A weak positive linear relationship between fecundity and carapace width was noted, as well as a high correlation with total egg weight. In the eastern Mediterranean, maturity sizes of females were smaller than those in the native region of the species.     

A Colpoda aspera isolate from animal faeces: In vitro cultivation and identification

A colpodean ciliate was found in the faeces of experimental rabbits. It was initially cultivated in medium mixed with 2% (w/v) rabbit faeces. Subsequently, two chemically defined media, designated CA-1 and CA-2, were found to be suitable for axenical cultivation of the ciliate. The maximum abundance of the ciliate isolate in the CA media was 1–2 × 10⁵ cells/ml. The ciliate isolate was further identified with silver impregnation and molecular analysis. Features of the left oral polykinetid, somatic dikinetids, and sliverline pattern were similar to those of Colpoda aspera as described by Foissner (1993). The 18S small subunit ribosomal RNA gene of the ciliate isolate shared 99% sequence identity with that of C. aspera, with 100% coverage, and formed a sister clade in the phylogenetic tree with the reference C. aspera isolate. In addition, the trophozoite of C. aspera could proliferate over a temperature range from 25–37 °C. When resting cysts were cultivated in CA-1 medium at 30–35 °C, 98.2% of the trophozoites were detached from the cyst wall after 7 h.     

Aspects of the reproductive biology of Pseudaphycus maculipennis (Hym: Encyrtidae), a parasitoid of obscure mealybug,Pseudococcus viburni (Hem: Pseudococcidae)

Laboratory experiments to determine aspects of the reproductive biology of Pseudaphycus maculipennis are described. All experiments were carried out at a constant temperature of 21 ± 2 °C, a 16-h photoperiod and ambient RH. Pseudaphycus maculipennis was shown to be an arrhenotokous, synovigenic, gregarious endoparasitoid of Pseudococcus viburni. Females and males lived for 16 and 11 days, respectively, when fed either honey-agar or mealybug honeydew. Relatively, large instars (third instar or adult females) were preferred for oviposition; mated females parasitized more mealybugs than unmated females, and the progeny sex ratio favored females by 3:1. Egg load increased with age from emergence to day 8, averaging 23 mature eggs/female. Mean realised daily fecundity never exceeded 5, with a mean lifetime fecundity of 46 eggs/female. Parasitised mealybugs remained alive for about 5 days and then mummified. Total development period was 20–21 days (larva 4–5 days, prepupa 3 days, pupa 8–9 days). Development periods of eggs and individual larval instars were not measured. A mean of 3.01 ± 0.1 parasitoids/mealybug were reared after individual parasitism events, increasing through super-parasitism (either self or conspecific) to 9 parasitoids/mealybug when hosts were exposed to competing females. Pseudaphycus maculipennis progeny emerged from the mummies in discrete cohorts over periods ranging from 3 min to 18 h (depending on the number of cohorts).     

Biology and thermal requirements of Chrysoperla genanigra (Neuroptera: Chrysopidae) reared on Sitotroga cerealella (Lepidoptera: Gelechiidae) eggs

Chrysoperla genanigra Freitas is a common green lacewing associated with melon pests in the Northeastern Brazil. All life stages of this recently described species were studied under a range of constant temperature conditions (17, 21, 25, 29, 33, 35 and 37 °C), a photoperiod of 12 h:12 h (L:D) and 70 ± 10% relative humidity. Adults of C. genanigra were fed on a diet consisting of a 1:1 (v/v) mixture of brewer’s yeast and honey, while larvae were provided with eggs of Sitotroga cerealella (Olivier) ad libitum. The duration of preimaginal development of the species was inversely proportional to temperature and ranged from approximately 63 days at 17 °C to 15 days at 35 °C. The percentage of adult emergence varied from 6.7% at 17 °C to 76.7% at 25 °C, although no larvae were able to complete development at 37 °C. The lower thermal threshold for total preimaginal development was approximately 10.8 °C and the thermal requirement was 336.7 degree-days. Egg production, along with the longevity of both males and females, were significantly affected by temperature. It is concluded that the best temperature for rearing C. genanigra is 25 °C, with the lowest preimaginal mortality and the highest egg production (992.7 eggs/female).     

A comparative study of the use of inorganic carbon resources by Chara aspera and Potamogeton pectinatus

We studied the potential role of dissolved inorganic carbon (DIC) in determining vegetation dominance of Potamogeton pectinatus L. and Chara aspera Deth. ex Willd. by monitoring the seasonal dynamics of DIC in a shallow lake and comparing the use of DIC of the two species. The HCO₃⁻-concentration in summer dropped from 2.5 to <0.5 mM with seasonally increasing Chara biomass, whereas outside the vegetation concentrations remained at 2.5 mM. Inside Potamogeton spp. vegetation DIC decreased from 2.5 to ca. 0.75 mM HCO₃⁻. A growth experiment showed ash-free biomass for P. pectinatus was nearly two times as high as for C. aspera at 3 mM HCO₃⁻, but almost two times lower at 0.5 mM than at 3.0. In a separate experiment, P. pectinatus precultured at a relatively low HCO₃⁻-level had a lower net photosynthetic rate (P_max, 0.1 mmol O₂ g⁻¹ DW h⁻¹) than C. aspera (P_max, 0.1 mmol O₂ g⁻¹ DW h⁻¹) over the range of HCO₃⁻-concentrations tested (P_max, 0.14 mmol O₂ g⁻¹ DW h⁻¹). In response to CO₂ no significant differences between the compensation points (P. pectinatus, 28 mM; C. aspera 66 mM), were observed, but the photosynthetic rate increased faster than for C. aspera than for P. pectinatus. Under field conditions, the use of CO₂ is not important since inside vegetation CO₂-concentrations were below 10 μM, and thus, not available for photosynthesis of either species during the main part of the growth season. It is suggested that C. aspera may be a better competitor for HCO₃⁻ than P. pectinatus in conditions with a low HCO₃⁻ supply. As HCO₃⁻ is a strong limiting factor for growth inside the vegetation and probably the only carbon source available, the superior ability of C. aspera to use HCO₃⁻ may be an important factor explaining its present dominance in Veluwemeer.     

Bionomics of Orasema simplex (Hymenoptera: Eucharitidae), a parasitoid of Solenopsis fire ants (Hymenoptera: Formicidae) in Argentina

Biological characteristics of the parasitoid Orasema simplex Heraty (Hymenoptera: Eucharitidae), a potential candidate for the biological control of fire ants in the United States were investigated. Female survivorship, fertility and oviposition preferences were studied in the laboratory. Naturally parasitized colonies were examined to determine offspring sex ratio, development success and time, and to artificially parasitize healthy ant colonies. In addition, field studies were carried out to establish natural oviposition substrates and adult activity patterns. Orasema simplex female survivorship was 3.6 ± 1.5 days. Newly emerged females contained 613.5 ± 114.0 mature eggs. The adult development success in natural parasitized colonies was 22.2% with a female-biased sex ratio (4:1). The time required from planidia to adult was 29.5 ± 5.4 days. In the field, adults were mostly found around the ant nests at midday. A broad range of plant species was observed as oviposition substrates. The transfer of planidia to healthy ant colonies was achieved but the development success was very low. Orasema simplex appears to have a limited potential as a fire ant biocontrol agent because of cosmetic damage to a wide variety of plants used for oviposition. However, further studies are necessary to evaluate the real damage exerted by oviposition punctures.     

The influence of maternal thermal environments on reproductive traits and hatchling traits in a Lacertid lizard,Takydromus septentrionalis

The thermal environment can induce substantial variation in important life-history traits. Experimental manipulation of the thermal environment can help researchers determine the contribution of this factor to phenotypic variation in life-history traits. During the reproductive season, we kept female northern grass lizards, Takydromus septentrionalis (Lacertidae), in three temperature-controlled rooms (25, 28 and 32 °C) to measure the effect of the maternal thermal environment on reproductive traits. Maternal thermal environment remarkably affected reproductive frequency and thereby seasonal reproductive output, but had little effect on reproductive traits per clutch or hatchling traits. Females kept at 32 °C produced more clutches and thus had shorter clutch intervals than females from 28 to 25 °C. Clutch size, clutch mass, relative clutch mass, egg size and hatchling traits did not vary among the three treatments. The eggs produced by the females were incubated at 27 °C and the traits of hatchlings were measured. The result that egg (offspring) size was independent of maternal thermal environments is consistent with the prediction of the optimal egg size (offspring) theory. The eggs produced by low temperature females (28 and 25 °C) took longer time to complete their post-oviposition development than did eggs produced by high temperature females (32 °C). This suggests that the eggs from low temperatures might have been laid when the embryos were at relatively early stages. Therefore, maternal thermal environment prior to oviposition could affect post-oviposition development in T. septentrionalis.     

Distribution,biology, and ecology of the deep‐water squat lobster Galacantha diomedeae (Crustacea: Decapoda: Galatheoidea: Munidopsidae) in the Mexican Pacific

During deep‐water exploratory surveys in the Mexican Pacific, 134 specimens of Galacantha diomedeae were collected between 1,035 and 2,136 m depth, below the Oxygen Minimum Zone. Greatest densities of G. diomedeae were observed between 1,300 and 1,600 m, with a maximum of 71 organisms per hectare at 1,318 m, and no clear bathymetric pattern of size distribution was detected. A total of 67 males, 43 ovigerous females, and 24 non‐ovigerous females were collected. The global sex ratio was 1:1, with some predominance of females shallower than 1,300 m and the opposite pattern at 1,300–1,600 m. Ovigerous females (carapace width [CW]=15.5?32.3 mm) were significantly larger than other females (CW = 5.1?29.9 mm), and females (including all females) were larger than males (CW = 6.0?29.9 mm). Among males and among all females, the growth coefficient was near 3 (Student's t test, males = 0.0027, all females = 0.0041; for both males and females, p > 0.05), indicating isometric growth. Ovigerous females were present all year, except in January, suggesting continuous reproduction. The observed low numbers of eggs (11–126), large egg sizes (2.07–2.77 mm), and advanced embryos at stage 5 are consistent with extended, lecithotrophic embryonic development with a reduced pelagic phase of the larvae. The relationship between ovigerous female size (N = 43) and number of eggs per female was marginally significant (y = 8.0474x–98.297; R² = 0.373), and there was no significant relationship between egg size and carapace size. There was no clear increase in egg size with embryonic development (phases 1–5). Individuals of G. diomedeae were found in a narrow range of environmental conditions, and mainly occupied oxic water (DO ≥0.5 ml/L) and sediments with intermediate to low organic carbon content.     

Epibiosis of Calpensia nobilis (Esper) (Bryozoa: Cheilostomida) on Posidonia oceanica (L.) Delile rhizomes: Effects on borer colonization and morpho-chronological features of the plant

Shoots of the Mediterranean seagrass Posidonia oceanica (L.) Delile can be overgrown with a thick encrustation of the bryozoan Calpensia nobilis (Esper) (Chelostomida) particularly under high hydrodynamic conditions. We compared shoots with and without this encrustation and assessed whether it affected shoot morphology and production, and incidence of polychaete borers. The borers collected were represented by three species of polychaete Eunicidae (Lysidice ninetta, Lysidice collaris and Nematonereis unicornis). Shoots affected by overgrowth of C. nobilis showed a significantly lower borer frequency (17% versus 49%), lower values of both yearly biomass of the rhizome (mean 6.3 mg/year in shoot with C. nobilis versus 8.3 mg/year in shoot without) and biomass/elongation (B/E) ratio, and lower mean sheath thickness (0.25 mm versus 0.30 mm), while the mean width of the leaves was slightly higher (1.0 mm versus 0.7 mm). Significant Spearman coefficient's values were estimated between carbonate mass of C. nobilis and rhizome length, muff length and rhizome length, and maximum thickness of the muff and rhizome length. Plant and bryozoan morphometrics allowed to estimate between 5 and 10 years the colonization age of C. nobilis on the living shoots studied.     

Juvenile hormone-mediated reproduction induced by a sublethal concentration of imidacloprid in Cyrtorhinus lividipennis (Hemiptera: Miridae)

The Hemipteran predator, Cyrtorhinus lividipennis, feeds on the eggs and nymphs of rice planthoppers and leafhoppers. We previously demonstrated that sublethal concentrations of imidacloprid stimulated the reproduction of C. lividipennis. Considering the essential roles of juvenile hormone (JH) in insect reproduction, we speculated that sublethal concentrations of imidacloprid may stimulate the reproduction of C. lividipennis by regulating JH level. To test this, we cloned C. lividipennis JH acid methyl transferase (ClJHAMT) and JH esterase (ClJHE), which are responsible for JH biosynthesis and degradation genes, respectively. We then knocked down ClJHAMT by injecting dsRNA into C. lividipennis nymphs and found that emerging female adults exhibited 88.8% lower expression of the vitellogenin gene (ClVg) and the number of eggs was reduced by 41.5% as compared with controls. Silencing ClJHE increased ClVg mRNA expression by 275.0% but did not affect fecundity. A sublethal concentration of imidacloprid (LC₂₀) increased the JH titer in females by 35.3% and 60.6% at 24 and 48 h post-emergence, respectively. In treatments containing both imidacloprid and dsJHAMT, the silencing of CLJHAMT reduced the number of eggs produced by adult females by 21.4% as compared to the control (imidacloprid + dsGFP). Our results indicated that sublethal concentration of imidacloprid may induce C. lividipennis reproduction by upregulating JH level via JHAMT. The finding could provide valuable information for improved integration of C. lividipennis and insecticides in pest management.     

Quality assessment of Riptortus pedestris (Hemiptera: Alydidae) eggs cold-stored at different temperature and relative humidity regime

Supplementation of host resource can be more economical method for the biological control of insect pest compared to direct release of adult parasitoids. Periodical release of non-viable cold-stored eggs of Riptortus pedestris (Fabricius) (Hemiptera: Alydidae) has been found to enhance parasitism of this pest in soybean fields. To find the optimum environmental conditions for cold storage of these host eggs, we evaluated nine different combinations of temperature (2, 6, and 10 °C) and relative humidity (high 90–95%, medium 70–75%, and low 30–35%). After 30 d of cold-storage, eggs were weighed and held at 26.6 °C and 75% relative humidity for 8 d before testing. To test the eggs’ suitability as hosts following cold storage, females of Ooencyrtus nezarae Ishii (Hymenoptera: Encyrtidae) were released individually onto batches of eggs, and parasitization rates and the development, emergence, sex ratio, adult longevity, and size of parasitoid progeny were examined. Eggs stored at high relative humidity showed less weight loss than those stored at low relative humidity. The number of eggs parasitized was highest (5.9/15) on eggs stored at 6 °C and high relative humidity. Developmental times and adult emergence were optimal on host eggs stored at 2 °C and high relative humidity. A significantly lower proportion of eggs produced male parasitoids when eggs were stored at 2 or 6 °C. Adult longevity was not affected by egg storage conditions, but adult size of progeny decreased in eggs stored at 10 °C. In conclusion, eggs of R. pedestris stored below 6 °C and with a high relative humidity maintained the best quality for parasitization by O. nezarae.     

The effect of diet on longevity,fecundity, and the sex ratio of Clitostethus arcuatus (Rossi) (Coleoptera: Coccinellidae)

Clitostethus arcuatus is a major, cosmopolitan predator of some Aleyrodidae. Field collected adult beetles were reared in the laboratory on different diets: Siphoninus phillyreae eggs, Trialeurodes vaporariorum eggs, Sitotroga cerealella eggs, or an artificial diet consisting of honey, yeast, and pollen. All experiments were conducted at 25 ± 2 °C, 65 ± 5% RH and a photoperiod of 16:8 (L:D) h. Female and male C. arcuatus consumed a mean (± SE) of 61 ± 0.6 and 27 ± 0.9 T. vaporariorum eggs d^? 1, respectively, and a mean of 56 ± 2.2 and 29 ± 1.1 S. phillyreae eggs d^? 1, respectively. Significant differences were noted between sexes and between hosts consumed by female C. arcuatus. No feeding occurred on S. cerealella eggs. Although there was a significant difference between rates of oviposition due to diet, fertility rates on different diets did not show significant differences. The sex ratio of C. arcuatus (female:male) was 51.4:48.6, 55.2:44.8, and 54.6:45:4 when adults fed on T. vaporariorum, S. phillyreae, and artificial diet, respectively. These differences were not significantly different. Average longevity (± SE) was 66.4 ± 2.6, 54.9 ± 2.5; 77.3 ± 6.9, 67.5 ± 7.2; and 86.4 ± 4.5 70.3 ± 3.6 days for female and male C. arctuatus, respectively, on T. vaporariorum, S. phillyreae and artificial diet, respectively, with significant differences between sexes and diets. Although developmental duration on T. vaporariorum was longer than ash whitefly, this difference was not significant (mean 27.68 ± 0.31 and 25.09 ± 0.21 days for predators reared on T. vaporariorum and S. phillyreae, respectively). Given its longevity and fecundity on T. vaporariorum, C. arcuatus may be a good choice for mass release on glasshouse crops infected by greenhouse whitefly.     

Fine-scale environmental heterogeneities of tidal creeks affect distribution of crab burrows in a Chinese salt marsh

Tidal creeks are an important structure of salt marshes in estuarine ecosystems, providing valuable ecosystem services to wildlife in the estuary. To determine the effects of environmental heterogeneities within tidal creeks on the features of crab burrows, we divided a typical creek section into four parts (i.e., microhabitats): bottom, slope, edge and flat, investigated the distribution of crab burrows and sediment properties on creek sections in the Yangtze River estuary, and compared the burrow distribution in tidal creeks with that in non-creek areas. Our results showed that from the creek bottom to flat soil water content declined (F_3, 60 = 93.8, p < 0.001), and the variations of other sediment physical and chemical properties associated with the change of soil water content were significant among the microhabitats on the creek sections (p < 0.001 for pH, conductivity, and grain size). No crab burrows were found at the creek bottom. The burrows on the slope were smaller in size (p < 0.001 for burrow opening diameter) while the density was higher than that at the edge and on the flat (F_2, 45 = 31.2, p < 0.001). Moreover, although the correlations between burrow distribution and sediment properties varied among the microhabitats on the creek sections, crabs generally selected relatively solid sediments to build their burrows. On the slope, there was a significantly negative relationship between burrow density and soil water content (r² = 0.53, p < 0.001). At the edge, the correlation between total burrow opening area and soil water content was significantly negative (r² = 0.44, p < 0.002). The density of small crab burrows (<10 mm) was greater, but that of large burrows (>10 mm) was lower in tidal creeks than in non-creek habitats. Therefore, sediment properties showed a gradual transition from hydrophytic to terrestrial environments on the creek section, which caused significant differences of burrow distribution among the microhabitats. The creeks of tidal salt marshes could affect ecological processes and functioning through affecting crab burrows.     

Biology of Apanteles myeloenta (Hymenoptera: Braconidae), a larval parasitoid of carob moth Ectomyelais ceratoniae (Lepidoptera: Pyralidae)

The carob moth, Ectomyelois ceratoniae (Lepidoptera: Pyralidae), is the most important pest of pomegranate orchards (in terms of economic damage) within Iran, and hence, several control procedures, including biological methods of control, have been attempted as a means of controlling populations of this insect. This research was carried out in order to study the biology of Apanteles myeloenta (Hymenoptera: Braconidae), a larval parasitoid of the carob moth. Laboratory studies were conducted to determine larval developmental time, adult longevity, sex ratio, parasite progeny production, and host stage preference of A. myeloenta. At 25 ± 1 °C, immature developmental time (egg to pupa; mean ± SE) was 28.33 ± 0.85 days and 27.46 ± 0.37 days for male and females, respectively. Adult females survived on average 17.5 ± 0.14, 11.7 ± 0.22, 3.4 ± 0.18, and 2.8 ± 0.12 days at 25 C when provided with honey and water, honey only, water only or no food source, respectively. The sex ratio (females to males) of A. myeloenta was 1:3.5 from hosts parasitized in the first instar, 1:3 for second instars and 1:2 for third instar carob moth larvae. Female A. myeloenta typically preferred to parasitize second instar over third or first instar. The oviposition activity peaked on the 7th and 8th days following emergence, when provided with honey, and 10% sucrose solution, respectively.     

Behavioral and reproductive responses of female opossums to volatile and nonvolatile components of male suprasternal gland secretion

Female gray short-tailed opossums (Monodelphis domestica) lack an estrous cycle and are induced into estrus by exposure to a pheromone in male scent marks. Behavioral and physiological responses of females to the volatile and nonvolatile components of scent marks were examined in two experiments. Young females (n = 9) were tested prior to and during their first estrus for behavioral responses to scent marks, collected on a 7-ml glass vial rubbed over the suprasternal gland of a mature male. The response to volatile components of the scent mark, recorded when marked and unmarked vials were covered with a perforated shield, was compared to the response to these vials when unshielded. Estrous females nuzzled the shields over marked vials (55.8 ± 8.5 nuzzles/10 min) more than the shielded clean vial (10.9 ± 2.4) (P < 0.05); a similar response was observed in anestrous females. Nuzzling of unshielded, scent-marked vials was higher (P < 0.05) during anestrus than in the same females when in estrus. The role of nonvolatile pheromones in reproductive activation was tested in adult females (n = 11) exposed for up to 14 days to a shielded, marked vial or to an unshielded, marked vial in a crossover design. All females exposed to unshielded vials expressed estrus, and 10 copulated. Only 2 females expressed estrus (significantly fewer, P < 0.05), when exposed to shielded marked vials, and neither copulated. These results demonstrate that females detect and respond behaviorally to both volatile and nonvolatile components of male suprasternal gland secretion, but the estrus-inducing pheromone in these secretions is nonvolatile.