Oviposition Site Selection Structures Niche Partitioning Among Coccinellid Species in a Tropical Ecosystem.

The competitive exclusion hypothesis suggests that coexisting related species using similar resources in nature should partition their realized niches. This hypothesis has direct implications for conservation strategies using biological control, taking into consideration the shifts caused by the introduction of natural enemies in a local community. Such introductions typically lead to disruptions in species interactions and interfere with community structure. In this study, we asked whether community structure of aphidophagous lady beetles is determined by the distribution of specific plants and aphids. To answer this question, we describe the distribution patterns of lady beetles (adults, larvae, and egg clusters) relative to plants and aphids in eight crop ecosystems in a central region of Brazil. We used canonical correspondence analysis to evaluate lady beetle distribution relative to selected habitat variables. Cycloneda sanguinea L., Hippodamia convergens Guérin-Méneville, Harmonia axyridis Pallas, and Eriopis connexa Germar (Coleoptera: Coccinellidae) differed in their use of plants and aphids. The association of egg clusters with specific plants/aphids was stronger than that of larvae or adults. In conclusion, lady beetle species occupied different niches, indicating different patterns of habitat use that may facilitate their coexistence in crop ecosystems. Furthermore, immature individuals had more specific environmental associations than adults, likely because female choice of oviposition sites influences their distribution and thus lady beetle community structure.

Reproduction of Blue-black Grassquits in central Brazil.

During the reproductive season Blue-black grassquit (Volatinia jacarina) males are found in clusters, wherein they exhibit a distinctive display that consists of repeated, vertical leaps while simultaneously producing a brief vocalization. The main objective of this study was to describe details of the species' reproductive behavior in a "Cerrado" area of central Brazil and compare these data with some studies carried out in other areas. The data obtained concerning different aspects of nesting, laying and hatching were generally similar to those obtained in previous studies in other areas. However, we found that the typical clutch size of two eggs per nest is lower, and egg and nestling mortality rates higher in our area than what has been reported elsewhere. Our results suggest that males differ in time expended with different activities according to their reproductive condition and also provide extensive parental care. We found that display execution rates peak in the early morning and in the late afternoon and are higher in the middle of the breeding season. We also found that there is an inverse relation between the height of the display leap and the height of the perch.

Reproduction of Blue-black Grassquits in central Brazil

During the reproductive season Blue-black grassquit (Volatinia jacarina) males are found in clusters, wherein they exhibit a distinctive display that consists of repeated, vertical leaps while simultaneously producing a brief vocalization. The main objective of this study was to describe details of the species' reproductive behavior in a "Cerrado" area of central Brazil and compare these data with some studies carried out in other areas. The data obtained concerning different aspects of nesting, laying and hatching were generally similar to those obtained in previous studies in other areas. However, we found that the typical clutch size of two eggs per nest is lower, and egg and nestling mortality rates higher in our area than what has been reported elsewhere. Our results suggest that males differ in time expended with different activities according to their reproductive condition and also provide extensive parental care. We found that display execution rates peak in the early morning and in the late afternoon and are higher in the middle of the breeding season. We also found that there is an inverse relation between the height of the display leap and the height of the perch.

Durante a estação reprodutiva, machos de tiziu (Volatinia jacarina) são encontrados agregados e apresentam uma exibição bastante conspícua, que consiste de saltos verticais associados a uma curta vocalização. Através de observações realizadas em uma área de Cerrado na região do Brasil central, este trabalho teve como objetivos detalhar alguns aspectos da biologia reprodutiva de V. jacarina e comparar tais dados com os poucos trabalhos existentes sobre a espécie. Os dados obtidos neste estudo com relação aos diferentes aspectos da nidificação, postura e eclosão dos ovos se mostraram semelhantes, em geral, àqueles encontrados em estudos anteriores, diferindo apenas com relação ao número de ovos por ninho (a maioria dos ninhos com apenas dois ovos) e às taxas de predação, que se mostraram mais elevadas. Os dados mostram ainda que machos variam com relação ao gasto de tempo com diferentes atividades de acordo com a condição reprodutiva e que os mesmos investem parentalmente. Foram encontradas ainda, que as taxas de execução de exibição são mais elevadas no início da manhã e no final da tarde, assim como também tem um pico no meio da estação reprodutiva. Encontramos também uma relação inversa entre a altura do salto da exibição e a altura do poleiro.