Development Rates of Some Finnish Gerris Fabr. Species (Het. Gerridae) in Laboratory Cultures

1974 ◽  
Vol 4 (3) ◽  
pp. 206-216 ◽  
Author(s):  
KARI VEPSALAINEN
Keyword(s):  
Larval Development ◽  
Continuous Light ◽  
Retarding Effect ◽  
Development Times ◽  
Development Rates ◽  
Temporary Habitats ◽  
Laboratory Cultures ◽  
Better Than

Abstract Egg and larval development times of Gerris odontogaster (Zett.) (COD), G. lateralis Schumm. (LAT), G. lacustris (L.) (LAC), G. thoracicus Schumm. (THO) and G. rufoscutellatus Lt. (RU) were studied. In species OD they are dependent on temperature. The roles of photoperiod, crowding and food remain open, even if continuous light seems to have a retarding effect on the larval development of OD and LAC. The development times of the subsequent instars of OD, LAT and LAC were shown to be of unequal lengths. When the development rates of different species were compared in 25―26°C, the species sequence from fastest to slowest was LAT, THO, LAC, OD and RU, i.e., disregarding RU and THO, just the opposite of the order experienced in nature in Finland. This raised the question of why the fastest species have not displaced OD in the microclimatically warmest habitats. The answer is supposed to lie in the seasonal, environmentally determined alary dimorphism of OD, which adapts it better than other species to microclimatically warm but at the same time temporary habitats.

The missing links: larval and post-larval development of the ascoglossan opisthobranch Elysia viridis

2000 ◽  
Vol 80 (6) ◽  
pp. 1087-1094 ◽  
Author(s):  
Cynthia D. Trowbridge
Keyword(s):  
Larval Development ◽  
Growth Rates ◽  
Shell Length ◽  
Larval Growth ◽  
Model Organism ◽  
Larval Life ◽  
Codium Fragile ◽  
Planktotrophic Larvae ◽  
Algal Diet ◽  
Better Than

The stenophagous ascoglossan (=sacoglossan) opisthobranch Elysia viridis has long been a model organism for the study of endosymbiosis or kleptoplasty as well as one of the few herbivores to consume the introduced green macroalga Codium fragile on European shores. Larval and post-larval dynamics of the ascoglossan were investigated. Planktotrophic larvae of E. viridis grew at 5–10 μm d−1 (shell length) at 15°C on a unicellular algal diet (the cryptophyte Rhodomonas baltica); larvae became competent one month post-hatching. Effective feeding and chloroplast acquisition typically started within 2–3 d of metamorphosis. Slugs grew about 8 mm in the first month of post-larval life. During this period, juveniles held in the light did not grow faster or survive better than conspecifics held in the dark; thus, functional kleptoplasty did not occur during first three weeks of benthic life. While larval growth rates and the nature of metamorphic cues are consistent with those of many other opisthobranch species with planktotrophic larvae, measures of post-larval growth—particularly as it pertains to kleptoplasty—is a new contribution to opisthobranch biology.

Section 5. Pyrethroid and endosulfan resistance: biology of resistant and susceptible larvae and pupae

1993 ◽  
Vol 1 ◽  
pp. 36-42 ◽  
Author(s):  
Neil W. Forrester ◽  
Matthew Cahill ◽  
Lisa J. Bird ◽  
Jacquelyn K. Layland
Keyword(s):  
Insecticide Resistance ◽  
Larval Development ◽  
Pyrethroid Resistance ◽  
Resistance Management ◽  
Selective Advantage ◽  
Successful Management ◽  
Pupal Development ◽  
Development Times ◽  
Selection Of ◽  
Female Laboratory

SummaryBoth pyrethroid and endosulfan resistant Helicoverpa armigera larvae were shown to have marginally longer development times. Pyrethroid resistant larvae were slower developers often requiring an extra moult before ultimately pupating to the same size pupa as susceptibles. There were no differences between pyrethroid resistant and susceptible pupal development times (male or female). Laboratory and field competition studies could demonstrate no selective advantage for either pyrethroid resistant or susceptible larvae or prepupae. Thus it would seem that the slightly longer larval development times do not manifest as significant biological deficits. This helps explain the gradually deteriorating pyrethroid resistance situation documented during evaluation of the Australian insecticide resistance management (IRM) strategy. There was no evidence of the selection of fitness modifiers (co-adaptation) to overcome the slower development of either pyrethroid or endosulfan resistant larvae. Endosulfan fitness disadvantages were not sufficiently researched in this study to discount the possibility of a fitness deficit contributing to the much more successful management of endosulfan resistance.

Competitive ability of neotropical Drosophila predicted from larval development times

Oikos ◽  
2001 ◽  
Vol 92 (2) ◽  
pp. 325-332 ◽  
Author(s):  
Coenraad L. Krijger ◽  
Yvonne C. Peters ◽  
Jan G. Sevenster
Keyword(s):  
Larval Development ◽  
Competitive Ability ◽  
Development Times

Observations on Oviposition in the Wheat Bulb Fly, Leptohylemyia coarctata (Fall.)

1958 ◽  
Vol 49 (2) ◽  
pp. 355-366 ◽  
Author(s):  
D. B. Long
Keyword(s):  
Continuous Light ◽  
Egg Laying ◽  
Constant Light ◽  
Temporary Increase ◽  
Laboratory Cultures ◽  
Light Darkness ◽  
The Mean ◽  
The Times ◽  
The Individual

SummaryIn laboratory cultures of Wheat Bulb Fly, Leptohylemyia coarctata (Fall.), a daily oviposition rhythm was observed in which egg-laying was virtually restricted to the afternoon and evening with maximum laying occurring in the two hours before nightfall. The time of oviposition coincided with that part of the diurnal flight rhythm, earlier observed, in which the flies actively congregated on wheat and this, it is suggested, could account for the fact, already recorded, that laying has been found to occur mostly on sites close to an infested crop.The oviposition rhythm was maintained for 24 hours in absence of light and therefore appeared to be partly inherent. However, it could be influenced by the times of exposure to light and disappeared in constant light. Darkness did not appear to affect the egg-laying rate but a temporary increase followed exposure to continuous light. Within the course of the experiments the rate was not affected by small changes in temperature.The individual fly laid up to 180 eggs in the laboratory in periodic batches of up to 42 eggs laid over periods of 1 to 6 days. This periodicity was obscured in cages containing a number of flies. Disproportionately small decreases in the mean daily laying rate occurred with increases in this laying period. Within the laying period the rate progressively increased with each successive day. The total number of eggs laid was not related to the number of ovarioles. In the laboratory, the rate of laying increased with age and most of the eggs were laid by relatively few flies.The rate of egg-laying and survival at different stages in the field is discussed and it is suggested that about two per cent. of the eggs successfully develop as matured females which lay an average of about 50 eggs each.

PHOTOPERIODIC ECOTYPES OF TREES

1954 ◽  
Vol 32 (3) ◽  
pp. 392-399 ◽  
Author(s):  
Olli Vaartaja
Keyword(s):  
Pinus Sylvestris ◽  
Tree Species ◽  
Continuous Light ◽  
Growing Season ◽  
Alnus Incana ◽  
Optimum Conditions ◽  
Southern Latitude ◽  
Northern Latitude ◽  
The Difference ◽  
Better Than

Seedlings of Pinus sylvestris L. and Alnus incana (L.) Moench. from two widely different latitudes were grown under two different photoperiods, but otherwise under optimum conditions. Under continuous light the seedlings from a far northern latitude grew better than those from a more southern latitude. This situation was reversed under short photoperiods. Since the days of the growing season at the northern latitude are extremely long and those at the southern latitude relatively short, the difference in growth of the seedlings is explained as being the result of heritable adaptation of the trees. The experimental results thus support the theory that within tree species there are "photoperiodic ecotypes" which during evolution have adapted themselves to the photoclimate of their environment.

scholarly journals Life history and phenology of Phylloicus pulchrus (Trichoptera: Calamoceratidae) in a tropical rainforest stream of Puerto Rico

2018 ◽  
Vol 66 (2) ◽  
pp. 814 ◽  
Author(s):  
Limarie J. Reyes-Torres ◽  
Alonso Ramírez
Keyword(s):  
Puerto Rico ◽  
Life History ◽  
Larval Development ◽  
Light Trap ◽  
Freshwater Ecosystems ◽  
Larval Abundance ◽  
Head Width ◽  
Larval Instars ◽  
Development Times ◽  
Adult Abundance

Caddisflies are abundant, diverse, and important insects in freshwater ecosystems.  However our knowledge on their life history is incomplete, in particular for the Neotropics. The objectives of this study were to describe the life history and phenology of Phylloicus pulchrus in the Luquillo Experimental Forest, Puerto Rico. Eggs and larvae were reared to determine the species lifespan and time in each instar. Larval instars were determined based on a head width vs. pronotal suture length correlation (N= 120). Larvae and benthic leaf litter were sampled monthly at a headwater stream for a year; all specimens were classified into instars based on their case size. Adult P. pulchrus were sampled monthly for a year with a light trap and at various times with a Malaise trap. Monthly environmental variables were related to species and sex abundance. There was a gradient of egg development where eggs (within compound masses) closest to the water were more developed. There were five larval instars and reared larvae showed longer development times and more variable body measurements in later instars. The best correlation for larval instar determination was case length-head width (Pearson= 0.90, P= 2.2e-16, N= 120). Phylloicus pulchrus has a multivoltine life cycle, with asynchronous larval development. Adult abundance was low. First to third instar larvae were influenced significantly by rainfall and rainfall seasonality had a negative significant effect on second instar larval abundance (ANOVA= 7.45, P= 0.02).Compound egg masses were probably oviposited by different females that gathered for oviposition. Phylloicus pulchrus follows the predominant developmental characteristic of Trichoptera of having five larval stages. Development times were longer than expected (longest times for a Phylloicus species) and may be an effect of laboratory rearing. The influence of rainfall (and seasonality) on different larval instars highlights the importance of this variable on early larval development. The cause of low adult abundance remains unclear, but may be related to low emergence rates and trap efficiency. Rev. Biol. Trop. 66(2): 814-825. Epub 2018 June 01. 

scholarly journals THE GENETICS OF MELANISM IN MALACOSOMA DISSTRIA HÜBNER (LEPIDOPTERA: LASIOCAMPIDAE)

Genetics ◽  
1979 ◽  
Vol 92 (2) ◽  
pp. 555-561
Author(s):  
Nancy Lorimer
Keyword(s):  
Larval Development ◽  
Morphological Traits ◽  
Autosomal Dominant ◽  
Low Frequency ◽  
Larval Survival ◽  
Malacosoma Disstria ◽  
Forest Tent Caterpillar ◽  
Development Times ◽  
Genetically Determined ◽  
Tent Caterpillar

ABSTRACT The forest tent caterpillar is polymorphic far two melanic genes affecting wing color of moths. These are the first genetically determined morphological traits reported for the genus. Dark (D) is a sex-limited, autosomal dominant with a phenotype of dark brown males. Frequencies in population samples varied from 8 to 44%. Characteristics of Dark and nonmelanic males were compared. Larval development times, larval survival and pupal weights were not significantly different, but mean fecundity was higher for females with Dark progeny. Band (b), a darkened area across the forewings, occurred in low frequency in both sexes.

Sign in / Sign up

Export Citation Format

Share Document