Egg Mass Deposition Research Articles

Sperm Precedence in Eysarcoris lewisi DISTANT(Heteroptera:Pentatomidae)in Relation to Duration between Oviposition and the Last Copulation

The last male sperm precedence (P2) in a pentatomid stink bug, Eysarcoris lewisi DISTANT, was studied using females mated with both normal and sterilized males. The mean P2 value in the first egg masses was about 40%. The mean P2 value increased as deposition of egg masses progressed, and showed almost complete last male sperm precedence in the forth egg masses. Among first egg masses, there was a significant positive correlation between P2 values and duration from termination of the last copulation to beginning of oviposition. these facts indicate that the duration between copulation and oviposition is important in determining P2 values. Females began oviposition an average of 55±37 (mean±S.D.) h after copulation. The function of prolonged copulation in this species is discussed.

Long term monitoring of amphibian populations with respect to the effects of acidic deposition

Amphibians breed in a variety of aquatic habitats in the United States. While the tolerance of low pH has been examined for many species of amphibians, those that breed in temporary ponds have been the most studied in terms of acidic precipitation. Some of the latter have been shown to have lethal limits for low pH that are close to or above the pH's found in many breeding ponds. Temporary ponds occur in large numbers in the areas of the country most affected by acidic precipitation. Many of these ponds are susceptible to acidification and reduced reproductive success of sensitive species of salamanders has been observed in acidic ponds. Additional practical and logistical considerations clearly make temporary ponds, and certain salamanders that breed in them, the best candidates for monitoring the long term effects of acidic precipitation on amphibian populations. We recommend a cost efficient monitoring scheme across three categories of acidic temporary ponds (low, medium, and high) that incorporates (a) chemical analyses of pond samples, (b) a census of the annual deposition of egg masses, as well as assessment of embryonic mortality in enclosed and unenclosed egg masses in the ponds, and (c) sampling of larval success. This plan offers the best opportunity for detecting changes in amphibian populations that are correlated with the acidity of precipitation, and would provide desperately needed long term data on the abundance of these amphibians.

Site Selection for Oviposition and Larval Feeding by the Tufted Apple Bud Moth (Lepidoptera: Tortricidae) on Apple in Pennsylvania

Intensive sampling was used to characterize the size and leaf type for tufted apple bud moth, Platynota idaeusalis (Walker), egg mass deposition, and to determine the association and site of larval feeding on fruit and foliage in Pennsylvania apple orchards. Results suggest tufted apple bud moth prefer to oviposit on smaller leaves (<20 cm2), and egg mass size was 0.16 cm2 during first brood and 0.12 cm2 during second brood. Significantly more first and second brood egg masses were oviposited on leaves within nonfruiting spurs than on either vegetative shoots or fruiting spurs. Both larval broods were found in association with leaves only rather than leaves and fruit. Fruit injury due to larval feeding during both broods occurred more on the calyx (sepals) surface area than the side or stem surface areas of the fruit. In cultivar comparisons of fruit, more surface injury was located on the site of the fruit from ‘Stayman’ trees than for ‘Golden Delicious’ trees.

Patterns of Egg Mass Deposition of Platynota idaeusalis (Lepidoptera: Tortricidae) within an Apple Orchard

Two field releases of rubidium (Rb)-labeled, laboratory-reared adult Platynota idaeusalis (Walker) were conducted to measure female adult dispersal and egg mass deposition patterns within a 33-ha (about 7,450 trees) apple orchard in Adams County, Pa. In both studies >3,200 virgin male and female adults (♂:♀ ratio = 1.1:1.0) were reared from rubidium-incorporated diet (3 g Rb/liter) and released on four center trees. Trees were randomly sampled for hatched and unhatched egg masses up to 500 m from the release sites. Atomic absorption spectrophotometry was used to detect rubidium in egg masses, and masses were considered marked if concentrations were > 10 ppb. Following the first release, 417 trees were sampled and 39% of the 222 egg masses collected were marked. Following the second release, 260 trees were sampled and 67% of the 346 egg masses collected were marked. The distribution of rubidium-labeled egg masses demonstrated that spatial patterns of egg mass deposition are primarily local and are affected by ambient air temperatures. For example, 90% of all recovered rubidium-labeled egg masses were found within 65 and 45 m of the release sites, and the most distant labeled egg mass was found at 250 and 170 m, respectively, following adult releases during a warm period in July (daily minimum temperatures, > 16°C) and a cooler period in September (daily minimum temperatures, <12°C).

Embryogenesis and the effects of temperature on embryonic development, juvenile growth rates, and the onset of oviposition in the fresh-water pulmonate gastropodPhysella cubensis

Summary Embryonic development in Physella cubensis is similar to that in other members of Physella, although trochophore or veliger-like embryonic stages previously noted in P. gyrina were lacking. Egg masses of adults collected from Shades Creek, Birmingham, Alabama were subjected to three temperature treatments (10, 20 and 30°C) within the normal range of temperatures experienced in the field, and developmental stages were documented until hatching. Hatched juveniles were raised in their respective temperature treatments to sexual maturation (onset of egg mass deposition). Temperature dramatically affected the time course of embryonic development. Juveniles (0.8 mm shell length) hatched in 36 days at 10°C, 13 days at 20°C, and 9 days at 30°C. Juveniles raised at 20 and 30°C produced egg masses 69 and 35 days after hatching and had shell lengths of 6.2 and 4.4 mm, respectively. No egg masses were produced at 10°C. Body size at first reproduction was significantly smaller in the individuals raised at 30 than at 20°C indicating that somatic growth takes precedence over reproduction at lower temperatures. Juveniles raised at 10°C did not attain sexual maturity over 100 days and reached only 1.5 mm shell length. The pronounced effect of temperature on rates of embryogenesis, juvenile growth, and the onset of sexual maturation suggests temperature plays a significant role in regulating the population dynamics of P. cubensis.

Enzyme cytochemical evidence for the activation of adenylate cyclase in the follicle cells of vitellogenic oocytes by the dorsal body hormone in the snail Lymnaea stagnalis

It is unknown what cell type(s) in the gonad of the hermaphroditic snail Lymnaea stanalis is the target(s) of the two gonadotropic hormones, dorsal body hormone (DBH) and caudo-dorsal cell neuro-hormone (CDCH). It was considered that the hormones might act by activating the adenylate cyclase (AC)-cAMP system in the targets. AC activation was determined histochemically. The CDCH (ovulation hormone) titer can be manipulated in vivo by inducing egg laying experimentally (“clean water stimulus”). The effect of the oocyte growth-stimulating DBH and also that of CDCH was studied in in vitro experiments. Only the follicle cells appeared to possess and AC-cAMP system (experiments with forskolin). This system can be activated by DBH, but not by CDCH. Activation can only be brought about in certain stages of the egg-laying process. In vivo this activation was apparent from 30–45 min until 2–3 hr after ovulation, i.e., until 0–1 hr after egg mass deposition. In vitro activation was possible 0–30 min after ovulation. Activation was only obvious in certain stages of oogenesis (not in follicle cells of younger oocyte stages). The results indicate that it is the follicle cells that are the targets for DBH. The possible role of the follicle cells is discussed. The question of what are the targets of CDCH remains unsolved. Apparently this hormone does not act via AC-cAMP, but via another second messenger.

Mate location strategies of gypsy moths in dense populations

In high-density populations, the male gypsy moth (Lymantria dispar) "appetitive" flight is primarily vertical and within 1-50 cm of tree boles. Preceding location of a female, males land on trees or occasionally tree foliage and walk while wing-fanning. In high-density populations females may mate before calling, often prior to wing expansion or hardening. Additional matings may occur before any or full deposition of egg masses. Virgin females are not coy, whether their wings are unexpanded, or hardened and held rooflike, or whether they are calling or not. They generally mate with the first willing male and do not exercise sexual selection by an acceptance or rejection reaction. The mating structure in dense populations would seem to reduce selective pressure for female emission of and direct male anemotactic flight to attractant pheromone. A low proportion of males "search" appropriate objects, especially tree trunks, in the walking-wing-fanning state. Such males often are successful in locating virgin females before calling commences. This male strategy presumably would not be successful in low population densities.

LARVAL REARING, METAMORPHOSIS, GROWTH AND REPRODUCTION OF THE EOLID NUDIBRANCHHERMISSENDA CRASSICORNIS(ESCHSCHOLTZ, 1831) (GASTROPODA: OPISTHOBRANCHIA)

1. Hermissenda crassicornis is a subannual nudibranch species that reproduces year-round. 2. There is a significant positive relationship between adult weight, diameter of the egg mass, estimated number of eggs per egg mass, and average number of eggs per capsule. 3. There is a planktonic veliger stage of 34 days minimum at 13 degrees -15 degrees C. 4. Larvae metamorphose on at least three species of hydroids. 5. To develop in reasonable numbers to a state competent to metamorphose veligers require a diet that includes phytoplankton of larger cell size (10-11 microm) than the commonly used Isochrysis and Monochrysis (5 microm). 6. Although Hermissenda feeds on a wide variety of sessile invertebrate species in the ocean, a diet of tunicate alone (Ciona intestinalis) promotes good growth and survival in the laboratory. 7. Egg mass deposition is initiated only after first copulation, except in the last month of life, and continues from about one-month post-metamorphosis to death, at about four months post-metamorphosis. Generation time (egg-to-egg) may be as short as 2.5 months. 8. A laboratory strain of Hermissenda is being established to provide animals of known history for research on the neural correlates of behavior. Animals, at least initially, are being selected for fast growth rate.

European Corn Borer: Lack of Synchrony of Attraction to Sex Pheromone and Capture in Light Traps123

During the 1971–72 spring and summer flights of Ostrinia nubilalis (Hubner), attractiveness of the synthetic sex pheromone Z-11-tetradecenyl acetate (Z-11-tda) was compared with light trap captures of male and female European corn borers and egg masses deposited in cornfields. Egg mass deposition maxima occur within 1–3 days of the Class 2 female (captured within 24 h after mating) maxima in the light trap. The male maxima in the light trap were synchronous with the female maxima (classes intercombined: Class 1—unmated, ovaries gravid; Class 2—spermatophore full, ovaries gravid; Class 3—spermatophore assumed partially depleted of sperm; and Class 4—spermatophore assumed depleted of sperm and ovaries assumed depleted of eggs. But when moderate to large populations of moths were present, the male maxima in the sex pheromone trap occurred after the female and male maxima in the light trap and after most egg masses had been deposited in cornfields. The results demonstrate that competition for males by feral females would reduce the efficacy of pheromone traps and also the importance of alternative monitoring systems for proper biological interpretation of European corn borer population data obtained from sex pheromone traps.

Mating Studies of Female European Corn Borers: Relationship Between Deposition of Egg Masses on Corn and Captures in Light Traps123

The nightly light trap catch of female Ostrinia nubilalis (Hübner) was divided into Class l—unmated-ovaries gravid; Class 2—full spermatophore-ovaries gravid; Class 3—spermatophore assumed partially depleted of sperm; and Class 4—spermatophore assumed depleted of sperm, ovaries assumed depleted of eggs. Laboratory research showed that the majority of females in Class 2 shifted to Class 3 within 48 h after pairing. Field studies showed that egg masses deposited on 200 corn plants peaked 1–3 days after the light traps captured peak numbers of Class 2 females. The classification procedure showed that light traps did not sample similar proportions of the adult population when the population was low (129 females/trap) as when it was high (628 females/trap). When numbers of females captured were low, the proportion of females in Classes 3 and 4 was severely affected. Nevertheless, the results supported the value of light trap collections in monitoring populations of this species.

The Life History and Habits of Chrysomela crotchi Brown (Coleoptera: Chrysomelidae) in Northwestern Ontario

AbstractThe life history of Chrysomela crotchi, a univoltine species commonly found on trembling aspen, was studied in northwestern Ontario from 1959 to 1962. The most striking feature of its life history was the longevity of adults, which were capable of overwintering two successive years. Overwintered adults became active and began feeding in late May, and oviposition occurred from early June to late July. The incubation period was approximately 10 days and the three larval instars required approximately one month for development to the adult stage.Females laid more eggs during their second season and the highest number laid was 326. The number of eggs in an egg mass averaged 37.6, and the average interval between the deposition of egg masses was 4 days. Males and females mated more than once, but only one mating was necessary for a female to produce viable eggs throughout the season. Males were capable of fertilizing more than one female and remained potent for more than one season.Parasitism was low, and only two species of larval parasites were reared. Several predator species were observed preying on the immature stages. Predation and overwintering mortality appeared to be the most important control factors.