German cockroaches spend most of the day in aggregations within shelters, which they leave in nocturnal foraging trips; cockroaches are rarely seen outside shelters during daylight hours. However, when population density exceeds shelter availability, diurnal aggregations form in exposed, unsheltered locations. To determine if shelter availability affects fitness of B. germanica, we reared cohorts of nymphs in laboratory arenas with or without shelters, and measured reproduction and longevity of tagged adults. When shelters were available in arenas, nymphs developed faster, adults gained more body mass, and females produced more fertile oothecae than when arenas lacked shelters. Therefore, shelter alone has a significant positive effect on growth and reproduction of B. germanica, and reducing or eliminating shelters should affect population growth of B. germanica in residential and industrial settings. and César Gemeno, Gregory M. Williams, Coby Schal.
Spiders are generalist predators that contribute to the control of pests in agroecosystems. Land use management determines habitats including refuges for hibernation and aestivation. The availability of shelters on the ground can be crucial for maintaining populations of spider within crops. We studied the effect of the number of stones on the surface of the soil on the spider community in selected olive groves in Trás-os-Montes (northeastern Portugal). The number of stones significantly influenced the overall diversity of spiders, abundance of immature individuals and abundance of ground hunters. Agricultural management practices aimed at the conservation of soil microhabitats such as hedgerows, stonewalls and stones on the ground should be promoted in order to maintain or increase the number of shelters for potential natural enemies of pests., Jacinto Benhadi-Marín, José A. Pereira, José A. Barrientos, José P. Sousa, Sónia A.P. Santos., and Obsahuje bibliografii
Intercropping may have a positive effect on the abundance and activity of carabid beetles and therefore their response to intercropping yellow lupin with spring triticale was studied for a period of three years (2001-2003). Carabids were most numerous in yellow lupin monoculture and in the intercrop with the highest proportion of lupin. Important differences between the experimental treatments were found, but they were mostly non-significant because of the great variation between samples. It is supposed that the positive effect of lupin on carabid beetles was due to the shelter it provides. During the three-year study 59 species of carabid beetles were recorded. The most abundant species in each treatment was Pseudoophonus rufipes. Irrespective of the experimental treatment, this species was caught in the greatest numbers towards the end of each growing season. This was probably because of the greater soil coverage provided by the larger lupin plants at the end of the season.