The cabbage beetle, Colaphellus bowringi Baly undergoes an imaginal summer and winter diapause in the soil; adult emergence is spread over several months to more than 2 years, with prolonged diapause occurring in certain adults under natural conditions. The relationship between natural duration of diapause and postdiapause reproduction was investigated at 25°C under 12L: 12D photoperiod. The mean body weight of postdiapause adults with the long diapause duration of 21 months was significantly greater than with the shorter diapause duration of 5, 11 and 17 months. The longevity and mean total egg production of the postdiapause adult females with the long diapause duration of 21 months was significantly greater than that of postdiapause females with shorter diapause duration of 5, 11 and 17 months. All results demonstrate that extended diapause is associated with a high level of postdiapause reproductive performance. There is no negative trade off between diapause duration and the post-diapause reproductive traits that we measured in C. bowringi.
Absolute fecundity (Fa) of burbot Lota lota lota females from Lake Haƒcza was 47.3 - 439.8 × 103, the relative fecundity based on eviscerated weight (Fwo) was 617.9 - 1572 × 103, and that based of total weight (Fw) was 44.8 - 1234.5 × 103. Regression equations were calculated, approximating the most significant relationships between fecundity and total body length of burbot (Fa = 0.0138 Sl2.5678, Fa = 0,0099 Tl2.8129) and weight (Fa = 0.6481 W1.0144). Mean gonadosomatic indexes (GSI) increased slightly with body length from 3.9 to 8.8% for females and from 3.7 to 20.6% for males.
Reproductive traits are among the most important biological characteristics that facilitate or impede the establishment of non-native fish into new environments. In several tributaries of the Lower River Danube (Bulgaria), the round goby (Neogobius melanostomus Pallas, 1814) is a recent invader. Specimens from the edge of the invasion front were collected monthly (March 2017 to May 2018) from each river. The pioneer individuals displayed relatively small body sizes. First maturation of females occurs at 49 mm total length. Based on the dynamics of oocyte size and GSI, it was established that spawning begins in early spring, at a relatively low water temperature (6-7 °C). The breeding season extended from March to June. Average absolute fecundity was 162 ± 62 oocytes, while average relative fecundity was 94 oocytes/g ± 24. Female fecundity is linearly dependent on the length and weight. Both of the known male alternative reproductive tactics were observed. Body condition factor was lowest during April for both sexes. The relationship between reproductive traits and invasive potential in N. melanostomus is discussed.
The reproductive biology of the marbled goby, Pomatoschistus marmoratus (Risso, 1810), was studied in the Strymon River estuarine system (northern Greece) between September 1997 and August 1999. Samplings were conducted on a monthly basis at the mouth of the river using a bag seine net and overall a total of 4 563 individuals were collected. The total length of males ranged between 2.5 and 6.0 cm and that of females between 2.8 and 5.7 cm, while that of unsexed individuals ranged between 1.2 and 2.9 cm. Sex ratio was 1.54:1 in favour of the females and statistically different from unity. The spawning of the species was extended, occurring between February and May. Mean absolute fecundity (F) was 1 386 (SE=8) oocytes and showed a significant positive exponential relationship with total length (F=14.387TL2.92), and total weight (F=1351TW0.83) of the fish. The relative fecundity ranged between 878 and 3 444 oocytes/g of total weight. Mean size at first maturity was estimated at 3.82 cm for the females and 4.66 cm for the males.
This paper describes the reproductive characteristics of 93 neophytes (alien species introduced after 1500 A.D.) of the flora of the Czech Republic and compares trait values between naturalized invasive and naturalized non-invasive neophytes. Species were sampled and seed collected in the field from multiple localities in the Czech Republic. Traits related to seed production (propagule number per plant and per population), dispersal (propagule size, length/width ratio and weight; buoyancy; epizoochory; terminal velocity) and establishment (germination; seedling relative growth rate; seedling establishment) were measured for each species either in the field, in a common garden experiment or in the laboratory. Invasive species significantly differ from naturalized non-invasive species in propagule length/width ratio (by having lower ratio, i.e. more rounded propagules) and fecundity (invasive species are more fecund, both per individual plant and in terms of the population propagule production). Invasive species have proportionally fewer seedlings establishing in the autumn and better capacity for dispersal by wind than non-invasive species. The results for several traits differ depending on whether or not the effect of phylogeny is included in analytical models. Considering species relatedness expressed as a taxonomic hierarchy, invasive species have lighter propagules and higher population propagule numbers, and marginally significantly differ in producing more propagules per plant and having higher capacity for dispersal bywater.We found that most variation in invasiveness is linked to variation among species within genera. This distribution of relatedness means that predictions of whether a species will become invasive cannot be based on traits of the relatives of the given species at higher taxonomic levels. The distinction made in this paper, i.e. invasive species vs. naturalized but non-invasive species, can potentially contribute to a deeper understanding of the role of traits associated with invasiveness because the crucial transition from the naturalized to invasion stage is rarely addressed in invasion ecology.
The systemic effects of phytoecdysteroids were investigated by applying tested compounds to the roots of the rape plants. Evaluation of the effects was based on mortality, longevity, rate of development and fecundity of the cabbage aphid (Brevicoryne brassicae L., Sternorrhyncha: Aphididae) feeding on the shoot of the treated plants. The major ecdysteroid compounds tested were natural products isolated from a medicinal plant Leuzea carthamoides DC (Willd.) Iljin (Asteraceae): 20-hydroxyecdysone (20E), ajugasterone C (ajuC) and polypodine B (polyB). The compounds were tested in two concentrations (0.07 and 0.007 mg/ml) in water. In addition, we have also investigated the systemic effects of a special Lc-Ecdy 8 fraction isolated from L. carthamoides, which contained 20E, ajuC and polyB and at least six other minor compounds in addition to the above indicated ecdysteroids. HPLC analysis of the Lc-Ecdy 8 fraction indicated the presence of makisterone A and inokosterone in minor quantities. It appeared that all ecdysteroid compounds tested, with the exception of the most common, 20E, decreased the fecundity of cabbage aphids which fed on the contaminated rape plants. The mortality of larvae and adults significantly increased on plants treated with the Lc-Ecdy 8 fraction, and with ajuC or polyB compounds containing structural substituents in rather unusual positions. The most common phytoecdysteroid, 20E, with the typical and characteristic ecdysteroid structure, was the best tolerated of all phytoecdysteroids tested.
One of the factors affecting the effectiveness of predatory coccinellids in an aphid infested crop is the food specificity of the predator. The response towards six species of aphids (Sternorrhyncha: Aphididae) was therefore tested in one of the most abundant aphidophagous coccinellids in Bulgaria - Propylea quatuordecimpunctata (L.) (Coleoptera: Coccinellidae). All aphid species studied (Acyrthosiphon pisum Harris, Aphis craccivora Koch, Eucallipterus tiliae (L.), Euceraphis betulae (L.), Phorodon humuli (Schrank) and Myzus persicae (Sulzer) cultured on transgenic Bt and conventional (non-Bt) potatoes were suitable food according to the rate of larval development, larval mortality and adult fresh weight. Females of P. quatuordecimpunctata fed with M. persicae cultured on Bt potato, or on non-Bt potato or on a mixture of M. persicae from Bt potatoes and A. craccivora, laid a little more eggs than those fed only with A. craccivora.
Trissolcus grandis is an important egg parasitoid of sunn pest, Eurygaster integriceps Puton (Hemiptera: Scutelleridae), the most serious pest of wheat in Iran. The thermal requirements of two populations of T. grandis were studied at five constant temperatures ranging from 20-32°C. Thermal thresholds for development were calculated using linear regression and degree-day models were determined by fitting non-linear equations to the data. The lower threshold for development was estimated to be 12.5 and 12.1°C, respectively, for males and females of the Bonab population, compared to 14.4 and 14.5°C for those of the Qaramalek population. Complete development required 143.8 and 162.8 degree-days, respectively, for males and females of the Bonab population and 116.9 and 124.6 for those of the Qaramalek population. Thus, wasps from the warmer region (Qaramalek) developed faster than those from the cooler region (Bonab), but had a higher thermal threshold for initiating development. Bonab females attained their highest fecundity (117.7 ± 7.2) at the lowest temperature tested (20°C), whereas the fecundity of Qaramalek females was maximal (96.8 ± 11.5) at 26°C. Biological control programmes that seek to augment wasp populations in wheat fields early in the spring, when natural rates of sunn pest parasitism tend to be low, should consider wasp thermal requirements to ensure the selection and release of locally-adapted parasitoids.
It is clear that Levinas’s critique of the dominance within Western philosophy of the concept of totality in Totality and Infinity was intended as a response to totalitarian-ism, but the extent to which this determines the organization of the book and the way in which this takes place has been largely misconceived. This is because of the failure to take seriously the opening question of whether or not we are duped by morality. The ethical resistance of the face of the Other does not adequately address that question until morality is secured against the challenge issued by a philosophy that equates being with war and that takes place only through the account of the infinite time of fecundity. Fecundity concretized in the family is the site of resistance to the totalitarian tendencies of any state that seeks for the sake of its preservation to legislate procreation. Hence fecundity and Eros are “beyond the face.” This reading draws on the important role given to fecundity in Time and the Other as well as the texts newly available in the first three volumes of Levinas’s Oeuvres.
Data on the webs, prey spectrum, density and fecundity of Theridion impressum from three different habitats [fields of sunflower, fiddleneck (Phacelia), and apple trees] are presented and discussed. The volume of webs were found to vary between 5 (the first free instar) to 117 cm3 (subadult and adult specimens). The mean density of adult spiders per plant was 0.7 (sunflower), 1.5 (fiddleneck) and 1.2 (per apple branch). Spiders preferred to build webs in the upper part of vegetation or at the extremities of tree branches. The prey spectrum was assessed by collecting webs and identifying their contents. Prey items were primarily aphids (73%), Diptera (7.5%), acid Coleoptera and Hymenoptera (both 5.4%). Pests comprised 90% of the prey; the remaining 10% was accounted for by natural enemies, pollinators and other insects. The number of insects captured in webs differed among study habitats (sunflower > fiddleneck > apple tree) though this difference was not statistically significant. Due to greater numbers of aphids in webs on sunflower, the mean prey length was significantly smaller on sunflowers than in other plots. An index of fecundity was obtained by counting the number of eggs in eggsacs. This varied from 48 to 156 per eggsac and was not significantly different between study plots. The number of eggs was strongly correlated with numbers of prey captured per spider.