Patterns of emergence, import of egg energy and energy export via emerging dragonfly populations in a tropical pond

Abstract

IntroductionThe most abundant dragonflies Brachythemis contaminata, Orthetrurn sabina, Diplacodes trivialis, Pantalaflavescens and Trithemis festiva in the tropical pond Idumban emerged from November to April during the years 1973,1974 and 1975. The date of initiation of emergence of allthe species was synchronized and tied to the events following the north west monsoon in November. During the seasons '73-74 and '74-75, as many as 10,693 and 7,910 adults emerged; females outnumbered the males in all the 5 species; male populations of B. contaminate, 0. sabina, D. trivialis, P. flavescens and T. festiva represented 47, 48, 46, 49 and 44% during the '73-74 season, 48, 48, 46, 46 and 49% duringthe'74-75 season, respectively. The adult dragonflies equivalent to 2,442 Kcal emerged from the Pond during the season '73-74. Of this, B. contaminata contributed 30%, D. trivialis 7%, 0. sabina 12%, P. flavescens 23% and T. festiva 28%. For the season '74-75, the dragonflies equivalent to 1,602 Kcal emerged from the Pond and the contribution was in the following order: B. contaminata: 31%, 0. sabina: 8%, D. trivialis: 13%, P. flavescens: 27% and T. festiva: 21%. Import of energy due to inoculation of B. contarninata eggs into the Pond Idumban was 73 Kcal/year and the output from the Pond via emerging B. contaminata population alone amounted to 620 Kcal/year; the net energy loss from the Pond was 548 Kcal/year. During either season, as much as 99.7% of B. contaminata eggs failed to attain adulthood due to infertility (5.8%), unhatchability (12%) and predation during the egg and nymphal stages (82.5%). During the study, the GPP of the Pond was 26,073 Kcal/m 2 /year, and output of energy through emergence of 5 dragonfly species amounted to 0.0045 Kcal/m2/year, i.e. 0.00002% of the GPP is lost through the emerging carnivorous odonates; comparable values available for the emerging detritivorous chironomids, herbivorous dipterans and mayflies fall between .o and o. %. Dr. W. Junk b.v. Publishers -The Hague, The Netherlands

Risky Times? Mortality During Emergence in Two Species of Dragonflies (Odonata: Gomphidae, Libellulidae)

“…Other well known predators of emerging dragonflies are lizards (Johnson, 1963;Reinhardt & Möller, 1996), crocodiles (Corbet, 1959), frogs (Miller, 1964), spiders (Wright, 1943;Corbet, 1957;Mathavan & Pandian, 1977), wasps (Wright, 1943;Gasse and Kröger, 1996) and ants (Ubukata, 1981;Gribbin & Thompson, 1990). With the exception of ants, none of these taxa played a significant role in the predation of emerging O. uncatus and O. coerulescens at the CdV.…”

“…Individuals are then unprotected and exposed to harmful biotic and abiotic factors and mortality can be high. Mortality during emergence varies between 8 and 17% in dragonflies (Corbet, 1957;Mathavan & Pandian, 1977) and may reach 30% in damselflies (Thompson et al, 1985;Gribbin & Thompson, 1990). According to Corbet (1962) mortality during emergence may be caused directly or indirectly by physical factors, by overcrowding from other emerging specimens, and by predation.…”

Patrones de emergencia de Odonata (Insecta) en un hábitat lótico de Cuba oriental

“…Se confeccionó una matriz de trabajo que incluyó como variables el número de exuvias, la frecuencia de emergencia en cada época del año y el número de picos con valor mayor o igual a 50 % de emergencia por períodos climáticos. Se definió como período de emergencia notable, cuando los valores de emergencia fueron mayores o iguales a 50 % del total, y emergencia máxima al mayor registro de exuvias para cada especie, durante el año de muestreo (Mathavan & Pandian, 1977).…”

“…Para los odonatos de zonas templadas la regulación estacional de la emergencia se activa fundamentalmente por el fotoperíodo y los cambios de temperatura (Norling, 1984), donde la sincronización aumenta con la latitud. Por otro lado, en los trópicos, este evento depende en mayor cuantía de fluctuaciones en las precipitaciones (Mathavan & Pandian, 1977), así como de la variabilidad estructural de los hábitats dulceacuícolas (Corbet, Suhling, & Soendgerath, 2006). Estos criterios permiten inferir que la emergencia en los trópicos no es un proceso homogéneo (Suhling, 1995), sino temporalmente heterogéneo (Lutz & McMahan, 1973).…”

Occurrence Pattern Analysis of Dragonflies (Odonata) on the River Tisza Between Vilok and Huszt Based on Exuviae

“…Vegetation is also a key component in the stabilization of the river banks (Hickin, 1984;Davis and Gregory, 1994), furthermore it influences the emergence strategy of the riverine dragonflies, the selection of the place of emergence and the extent of larvae departure from water (Corbet, 1983(Corbet, , 1999Farkas et al, 2011). According to our experience, scientific literature is not always unified in the peculiarities of dragonfly larvae habitat selection as well as in the selection of their place of emergence (Trottier, 1973;Mathavan and Pandian, 1977;Geissen, 2000;Jakab, 2006;Hardersen, 2008). The typically changing channel and river bank structure of the upper Tisza section hinders the tracing of dragonfly assemblages and the recognition of quantitative changes.…”