Laboratory interspecific competition and grain-hosts selection experiments involving maize weevil (MW), Sitophilus zeamais (Motsch.) and larger grain borer (LGB), Prostephanus truncatus (Horn) were performed under amb...Laboratory interspecific competition and grain-hosts selection experiments involving maize weevil (MW), Sitophilus zeamais (Motsch.) and larger grain borer (LGB), Prostephanus truncatus (Horn) were performed under ambient temperature and relative humidity (25°C - 35°C and 70% - 80% relative humidity) in their major host cereal, maize grains. The species reproductive rate and grain-hosts preference were evaluated by a number of emerged adults. In combined infestation, both species competed intensively by simultaneously increasing their individuals’ emergence, 9-fold or greater than when reared alone. Even though both species simultaneously increased their progeny, S. zeamais was the dominant competitor and had a significant suppressant effect on P. truncatus. The selection result of grain-hosts showed that P. truncatus placed in the environment containing both uninfested maize grains and grains previously infested by S. zeamais, the insect prefers uninfested grains. Indeed, P. truncatus individuals’ emergences were significantly more important to uninfested grains than to infested grains. The weevil-infested grains seemed to have deterrent and detrimental effects on P. truncatus. Conversely, S. zeamais selection of grain-hosts was significantly (P = 0.0001) more attracted by P. truncatus infested grains than to uninfested grains. Sitophilus zeamais individuals’ emergences were significantly (P = 0.0008) more important to infested grains than to uninfested grains. The S. zeamais preference on grains previously infested would be stimulated by P. truncatus larval vibrations in grain.展开更多
Natural regeneration is the interaction of natural processes to restore the forest ecosystem. Its dynamics are influenced by the intensity and extent of a series of abiotic and biotic factors, which may be intrinsic o...Natural regeneration is the interaction of natural processes to restore the forest ecosystem. Its dynamics are influenced by the intensity and extent of a series of abiotic and biotic factors, which may be intrinsic or extrinsic. Knowing the importance of establishing natural regeneration within forest ecosystems, this work aimed to evaluate whether litter depth and trail distance influenced seedling abundance and richness in a forest fragment undergoing natural restoration. The hypothesis tested in this research was that abiotic factors influence the natural regeneration of this forest since they are factors that are directly linked to seed germination and seedling establishment. 30 plots of 1 m2 were randomly analyzed within the forest located on the brown trail. A millimeter ruler was used to diagnose the litter depth and a measuring tape to measure the distance from the plot to the edge. In each plot the seedlings were morpho-specified and each morphospecies had the number of individuals counted. Linear regression tests were performed to assess the relationships between species richness and trail distance and litter depth. The same was done for species abundance. All results showed that there is no relationship pattern between any of the variables. Other factors also influence the regeneration of a forest, such as luminosity and seed bank. Furthermore, litter depth is related to the successional stage of the forest. It was concluded that the abiotic factors tested do not influence the regeneration of the study area.展开更多
文摘Laboratory interspecific competition and grain-hosts selection experiments involving maize weevil (MW), Sitophilus zeamais (Motsch.) and larger grain borer (LGB), Prostephanus truncatus (Horn) were performed under ambient temperature and relative humidity (25°C - 35°C and 70% - 80% relative humidity) in their major host cereal, maize grains. The species reproductive rate and grain-hosts preference were evaluated by a number of emerged adults. In combined infestation, both species competed intensively by simultaneously increasing their individuals’ emergence, 9-fold or greater than when reared alone. Even though both species simultaneously increased their progeny, S. zeamais was the dominant competitor and had a significant suppressant effect on P. truncatus. The selection result of grain-hosts showed that P. truncatus placed in the environment containing both uninfested maize grains and grains previously infested by S. zeamais, the insect prefers uninfested grains. Indeed, P. truncatus individuals’ emergences were significantly more important to uninfested grains than to infested grains. The weevil-infested grains seemed to have deterrent and detrimental effects on P. truncatus. Conversely, S. zeamais selection of grain-hosts was significantly (P = 0.0001) more attracted by P. truncatus infested grains than to uninfested grains. Sitophilus zeamais individuals’ emergences were significantly (P = 0.0008) more important to infested grains than to uninfested grains. The S. zeamais preference on grains previously infested would be stimulated by P. truncatus larval vibrations in grain.
文摘Natural regeneration is the interaction of natural processes to restore the forest ecosystem. Its dynamics are influenced by the intensity and extent of a series of abiotic and biotic factors, which may be intrinsic or extrinsic. Knowing the importance of establishing natural regeneration within forest ecosystems, this work aimed to evaluate whether litter depth and trail distance influenced seedling abundance and richness in a forest fragment undergoing natural restoration. The hypothesis tested in this research was that abiotic factors influence the natural regeneration of this forest since they are factors that are directly linked to seed germination and seedling establishment. 30 plots of 1 m2 were randomly analyzed within the forest located on the brown trail. A millimeter ruler was used to diagnose the litter depth and a measuring tape to measure the distance from the plot to the edge. In each plot the seedlings were morpho-specified and each morphospecies had the number of individuals counted. Linear regression tests were performed to assess the relationships between species richness and trail distance and litter depth. The same was done for species abundance. All results showed that there is no relationship pattern between any of the variables. Other factors also influence the regeneration of a forest, such as luminosity and seed bank. Furthermore, litter depth is related to the successional stage of the forest. It was concluded that the abiotic factors tested do not influence the regeneration of the study area.
