The rate of colonization by macro-invertebrates on artificial substrate samplers

The influence of exposure time upon macro-invertebrate colonization on modified Hester-Dendy substrate samplers was investigated over a 60-day period. The duration of exposure affected the number of individuals, taxa and community diversity. The numbers of individuals colonizing the samplers reached a maximum after 39 days and then began to decrease, due to the emergence of adult insects. Coefficients of variation for the four replicate samples retrieved each sampling day fluctuated extensively throughout the study. No tendencies toward increasing or decreasing coefficients of variation were noted with increasing time of sampler exposure. The number of taxa colonizing the samplers increased throughout the study period. The community diversity index was calculated for each sampling day and this function tended to increase throughout the same period. This supports the hypothesis that an exposure period of 6 weeks, as recommended by the United States Environmental Protection Agency, may not always provide adequate opportunity for a truly representative community of macro-invertebrates to colonize multiplate samplers. Many of the taxa were collected in quite substantial proportions after periods of absence or extreme sparseness. This is attributed to the growth of periphyton and the collection of other materials that created food and new habitats suitable for the colonization of new taxa. Investigation of the relationship between ‘equitability’ and length of exposure revealed that equitability did not vary like diversity with increased time of exposure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72073/1/j.1365-2427.1979.tb01522.x.pd

New species of Ablabesmyia Johannsen (Diptera, Chironomidae, Tanypodinae) from the Neotropical Region, with description of male adults and immature stages

A new species of genus Ablabesmyia is described. The larvae were collected associated with aquatic macrophytes in ponds from the Southeast of Brazil. In laboratory, the larvae were reared to obtain pupae and adults.<br>É descrita uma nova espécie do gênero Ablabesmyia. As larvas foram coletadas associadas a macrófitas aquáticas de lagoas no Sudeste do Brasil. No laboratório, foram criadas para a obtenção das pupas e adultos

Embryology of Triatoma infestans (KLUG), (Hemiptera, Reduviidae), a Chagas' disease vector Embriología del Triatoma infestans, vector de la enfermedad de Chagas

This study reports the embryogenesis of T. infestans (Hemiptera, Reduviidae). Morphological parameters of growth sequences from oviposition until hatching (12-14 d 28ºC) were established. Five periods, as percent of time of development (TD), were characterized from oviposition until hatching. The most important morphological features were: 1) formation of blastoderm within 7% of TD; 2) germ band and gastrulation within 30% of TD; 3) nerve cord, limb budding, thoracic and abdominal segmentation and formation of body cavity within 50% of TD; 4) nervous system and blastokinesis end, and development of embryonic cuticle within 65% of TD; 5) differentiation of the mouth parts, fat body, and Malphigian tubules during final stage and completion of embryo at day 12 to day 14 around hatching. These signals were chosen as appropriate morphological parameters which should enable the evaluation of embryologic modifications due to the action/s of different insecticides<br>En este estudio se caracterizó el desarrollo embrionario del T. infestans (Hemiptera Reduviidae). Se establecieron parámetros morfológicos secuenciales de crecimiento desde la oviposición hasta la eclosión, (12-14 d 28ºC). Cinco períodos de crecimiento fueron determinados y expresados como fracciones porcentuales del tiempo total del desarrollo (TD) hasta la eclosión. Los eventos morfológicos mas importantes fueron: 1) La formación del blastodermo hasta el 7% del TD; 2) La aparición de la banda germinativa y su gastrulación transcurridos un 30% del TD; 3) El comienzo de la formación del cordón nervioso, de las extremidades, la segmentación torácica y abdominal y la formación del mixocele cuando la embriogénesis alcanzó el 50% del TD; 4) La terminación de la blastoquinesis, el desarrollo completo del sistema nervioso y la aparición de la cutícula embrionaria hasta el 65% del TD; 5) En la etapa final de la embriogenesis se observó la diferenciación del aparato mandibular, el cuerpo graso, los tubos de Malpighy. El embrión completa su organogénesis entre los 12 y 14 días. Estos parámetros morfológicos fueron seleccionados para evidenciar potenciales modificaciones embriológicas debidas a la acción ovicidas de diferentes insecticida