Ocorrência do besouro tigre Neotropical, Cylindera suturalis helvaea (W. Horn, 1903) (Coleoptera, Cicindelidae), em bancos de areia do Reservatório da Barragem da Pedra, Rio de Contas, Bahia, Brasil

The occurrence of the tiger beetle Cylindera (Plectographa) suturalis helvaea (W. Horn, 1903) in sandbanks of Reservoir Barragem da Pedra, Bahia, Brazil, is registered. Adult beetles were collected using entomological nets on sandbanks between May and September 2003. Cicindelids are one of the most conspicuous groups among invertebrates. That is why thay are well suited for bioindication of biodiversity as well as of disturbance and modification in terrestrial ecosystems.Neste estudo é registrada a ocorrência do besouro tigre Cylindera (Plectographa) suturalis helvaea (W. Horn, 1903) em bancos de areia no Reservatório da Barragem da Pedra, Bahia, Brasil. Indivíduos adultos foram coletados utilizando-se de redes entomológicas, entre os meses de Maio e Setembro de 2003. Cicindelídeos são um dos mais conspícuos grupos de invertebrados, sendo considerados como bons indicadores de biodiversidade assim como de distúrbios e modificações nos ecossistemas terrestres

Survival strategy of the bombardier beetle, Pheropsophus rivieri (Col.: Carabidae) in a Central Amazonian blackwater floodplain (Brazil)

Terrestrial invertebrates in the Central Amazonian floodplains have to cope with an annual inundation period of several months. Their life cycles are affected by this flood pulse, and most species have adopted seasonal univoltine reproductive regimes as a common survival strategy. We followed the phenology of adult bombardier beetles, Pheropsophus rivieri, at a blackwater river beach near Manaus/Brazil during 1997-1999. Gonad maturity was examined in female beetles. Adult beetles showed a pronounced seasonal activity pattern with the reproductive period confined to the first three months of falling water levels. It is concluded that P. rivieri has a seasonal, univoltine. and presumably semelparous life cycle, driven by the flood pulse. The presence of fat bodies in immature females during rising water levels indicates a delayed gonad maturation or gonad dormancy. The species exhibits a migratory survival strategy, typical for most carabid species from Central Amazonian floodplains, although it remained unsolved where adults pass the period of rising water levels. A possible parasitic relation of larval P. rivieri with mole crickets is discusse

Exceptional anoxia resistance in larval tiger beetle, Phaeoxantha klugii (Coleoptera : Cicindelidae)

The tiger beetle Phaeoxantha klugii inhabits Central Amazonian floodplains, where it survives the annual inundation period in the third-instar larval stage submerged in the soil at approximately 29 degreesC for up to 3.5 months. Because flooded soils quickly become anoxic, these larvae should be highly resistant to anoxia. The survival of adult and larval P. klugii was therefore tested during exposure to a pure nitrogen atmosphere in the laboratory at 29 degreesC. Adult beetles were not resistant (< 6 h). Survival of larvae decreased over time, maximum survival was 15 days, whereas time to 50% mortality was 5.7 days (95% confidence interval 3.8-7.9). Anoxia resistance was additionally tested in third-instar larvae submerged within sediment for 40 days before anoxia exposure in the laboratory. Anoxia resistance was greatly enhanced in these larvae, showing a survival rate of 50% after 26 days of anoxia exposure. It appears that the gradual flooding process and/or the submersion phase induced a physiological alteration, most probably a strong depression in metabolic rate, which requires some days for induction. The degree of anoxia resistance in larval P. klugii is remarkable among terrestrial arthropods worldwide, even more so considering the high ambient temperatures. The species is well-suited to serve as a model organism for studying the physiological mechanisms of anoxia and submersion resistance in terrestrial arthropods inhabiting tropical floodplains

Flight ability in nocturnal tiger beetles (Coleoptera : Carabidae : Cicindelinae) from Central Amazonian floodplains (Brazil)

Tiger beetles of the genera Phaeoxantha Chaudoir and Tetracha Hope are considered to be flightless or to fly only occasionally. Six species of these genera inhabit Central Amazonian floodplains and show strong differences in life cycles, behaviour, and habitats. From this background we investigated flight ability in these species by determining flight muscle development in specimens regularly collected between 1997-1999. Gonad states (in females) as well as teneral females were recorded to estimate beetle age. Of 1,946 adult beetles of these six species we dissected, 31.4% had fully developed flight muscles, suggesting flight ability. In the other 68.6% of specimens flight muscles were completely absent. Frequency of flight muscle presence varied greatly among species, ranging from 100% in Tetracha species, and 0 to 60% in Phaeoxantha species. No evidence for an "oogenesis flight syndrome" was found in females as flight muscle states were not correlated with age. These findings are interpreted as flight (muscle) dimorphism in Phaeoxantha species. Flight muscle presence in males and females was only different in P. klugii Chaudoir with flight ability being more frequent in females. Tetracha species use flight as an integral part of their survival strategy in Central Amazonian floodplains, unlike Phaeoxantha species. A possible correlation between the degree of flightlessness and habitat stability in Phaeoxantha species is discussed