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The effects of temperature (20°C, 25°C, 30°C) and photoperiod (16D:8N, 12D:12N, 8D:16N) on larval body weight, food consumption, egg production, and survival of Gastroidea viridula Deg. (Coleoptera: Chrysomelidae) were determined. Temperatures and photoperiods affected insect development time, larval body weight, and survival. Larvae continued development while 60 days at temperature of 20°C and photoperiod of 8D;16N, but only while 30 days at 30°C, 16D:8N and 12D:12N. Photoperiod not affected the oviposition period and number of eggs produced. Results show that both temperature and photoperiod significantly affects larval body weight and survival.
Rumex confertus Willd., niebezpieczny chwast charakteryzujący się wysoką reprodukcyjnością, pojawia się co roku na nowych stanowiskach. Chemiczna metoda walki z nim jest trudna ze względu na bogaty system korzeniowy. Przedstawione doświadczenia były prowadzone w latach 1997-1999 oraz 2001 w naturalnych warunkach siedliskowych Rumex confertus Willd. W pracy analizowano owady zasiedlające Rumex confertus Willd., a także zawartość substancji o charakterze wtórnych metabolitów. Stwierdzono, że szczaw omszony jest zasiedlany przez licznych roślinożerców. Szczególnie uszkadzane były jego organy generatywne. Wraz ze wzrostem uszkodzeń zwiększa się również ilość polifenolokwasów w roślinie.
Weeds, the detrimental plant organisms connected with the man's activity, need to be controlled. Human development and increasing mobility created an intentional or accidental introduction of the plants, of ten exotic ones, into new places, and ecosystems. Prevailing method of weed control consists in application of the chemicals. They are acting rapidly and radically eliminate the density of imdesirable plant population. However, the chemical formulas are often little selective, contaminate the environment and their effectiveness drops very fast with arising resistance of plant organisms. Biological methods of weed population control seem to bring a solution of this problem. Such methods are of particular research interest on the terrains of river banks, because of ecological reasons - a threat of surface water pollution. Rumex confertus Willd. plants seem to be complying with the qualification criteria as requested to biological weed control.
A field experiment was conducted to determine a direct effect of five herbicides selected on Rumex confertus Willd., and an indirect effect on phytophagous insects. Mossy sorrel is the host of Hypera rumicis L. (Coleoptera, Curculionidae), Apion miniatum Germ. (Coleoptera, Curculionidae), and Pegomya nigritarsis Ztt. (Diptera, Anthomyiidae). The herbicide treatment affected the plant growth, yet new leaf rosettes were produced again by the end of the summer. However, the herbicide treatment reduced the leaf area and the number of seeds damaged by larvae. The insect development, seasonal adult abundance, and feeding by larvae decreased significantly on the herbicide treated plants.
Biological methods of weed control are alternative to chemical treatments. Biological techniques are used where no possibility for chemical spraying occurs. Rumex confertus Willd. is an example of a plant-eater which is potentially more important than chemical compounds. The objective of the study was to evaluate population dynamics and the development of Hypera rumicis L. (Coleoptera, Cucurlionidae) on Rumex confertus Willd. as well as to determine effects of the injuries on growth of a plant.
Field research was conducted to determine insects occurring on Rumex confertus Willd. The experiments were carried out in 1997, 1998, 1999 and additionally in 2001 from April to late September. The field trials were located in the natural habitat of R. confertus on meadows near Vistula river; in Bydgoszcz (53013'N, 18015'E) and Toruń (5302'N, 18061'E) vicinities. Mossy sorrel was injured by the following pests in order of feeding impact: Mamestra dissimilis Knoch., Rhinoncus pericarpius L., Phyllobius virideaeris Laich., and Phyllobius maculicornis Germ. The losses of R. confertus biomass were recorded throughout the whole growing season until the plants desiccating. Two generations of M. dissimilis in both locations were recorded. In case of R. pericarpius and Phyllobius spp. one generation was observed.
There is currently a very favorable climate for biological control of pest weeds. Moreover, biological control plays a significant role in the Integrated Plant Protection Management. Traditional methods of weed control, such as cultivation and the use of herbicides are not practical or desirable for some stands of weeds, and biological control has become an attractive strategy for control of pest weeds. Control of Rumex confertus Willd. by natural enemies that reduce its density is the good example of utilizing biological control on the European and worldwide scale. The aim of the conducted studies was to evaluate the dynamic of population of Pegomya nigritarsis Ztt. (Diptera, Anthomyiidae) on Rumex confertus Willd. and to determine the impact of pest’s injuries on the growth of a plant.
Weeds are harmful organisms connected with human activities; therefore there is a need for their control. Human development and mobility have caused on purpose or purely incidental introduction of plants, exotic very often, to new sites and ecosystems. A dominating method of weed control is applying chemicals. However, chemical compounds are often of low selectivity, they also contaminate the environment and become ineffective quickly because of acquired resistance of treated organisms. The control of Rumex confertus Willd. and other weeds of the genus Rumex spp. is often not possible because of economical reasons. Large areas abundant in sorrel populations would require a large sum of money invested in expensive chemical control. Biological methods of weed control look far more promising solution to this problem. Rumex confertus Willd. is a plant corresponding to criteria to qualify it as an object for biological regulation. The objective of the study was to evaluate dynamic of population and development of the insects of the genera Gastroidea spp. (Gastroidea viridula Deg. and Gastroidea polygoni L.) occurring on Rumex confertus Willd.
Terrain and laboratory research were conducted to determine the potential of Gastroidea viridula Deg. (Coleoptera: Chrysomelidae) to control mossy sorrel (Rumex confertus Willd.). In a field study, the dynamicof plant biomass and number of larvae occurring on that plant were investigated. The Pearson’s linear correlation coefficient of biomass increase in time equalled, to r = 0.96. The regression equation showed, that the plant daily growth reached 29 g; and 210 g per week, consequently. In the laboratory, weight of consumed food by larvae, and larval body weight were measured at 20°C. First generation of G. viridula was taken into consideration. Total weight of consumed leaves by all three instars of a single larva, during 50 days of the development amounted to 1.243 g. Also seasonal abundance of larvae was observed. On May 25th the highest observed number of G. viridula larvae per plant ranged from 435 to 469 individuals. This species may be of usefulness in biological control of mossy sorrel.
Badania polowe i laboratoryjne prowadzono w celu oszacowania możliwości wykorzystania piętnówki zmiennej (Mamestra dissimilis Knoch., Lepidoptera: Noctuidae) do regulacji zachwaszczenia spowodowanego przez Rumex confertus (Willd.). W naturalnym siedlisku szczawiu badano dynamikę jego wzrostu oraz liczbę gąsienic piętnówki zmiennej zasiedlających roślinę w okresie 50 dni. Największą liczbę gąsienic odłowiono pod koniec pierwszej dekady czerwca, w czasie gdy roślina żywicielska miała już w pełni wykształconą rozetę. W warunkach laboratoryjnych badano wzrost masy ciała gąsienic oraz ich żerowanie w temperaturze 20°C. Zależności pomiędzy masą zjedzonych liści szczawiu omszonego a przyrostami masy larw L4 i L5 były statystycznie istotne (r = 0,97 i r = 0,88). Stwierdzono bardzo progresywny charakter żerowania larw L4, opisany równaniem 1. stopnia (r = 0,98). Wyliczono, że każdego dnia w ciągu 20 dni żerowania larwy zjadły o 5,9 mg więcej liści. Natomiast dla gąsienic L5 związek ten miał charakter funkcji 2. stopnia (r = 0,96). Oszacowana masa liści szczawiu omszonego, która uległa skonsumowaniu przez larwy piętnówki zmiennej w warunkach naturalnych, wyniosła 159,3 g, co stanowiło około 11% utraty biomasy żywiciela.
Field and laboratory research was conducted to determine the effect of five herbicides on Rumex confertus Willd. which is the host of Gastroidea viridula Deg. and Gastroidea polygoni L. (Coleoptera: Chrysomelidae). Herbicide treatment effected plant growth, but new leaf rosettes were produced by the end of the summer. Survival, seasonal abundance and development of investigated insects were significantly reduced. Beetles and larvae avoided feeding on herbicide treated plants.
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