Showing papers on "Bufo melanostictus published in 2009"

Association preference and mechanism of kin recognition in tadpoles of the toad Bufo melanostictus

Abstract: In experiments with specially designed choice tanks, tadpoles of Bufo melanostictus spend significantly greater amounts of time near kin than near non-kin. However, in the absence of kin members, they prefer to spend more time near non-kin rather than stay away in isolation in the opposite blank zone with no company. This implies that association of toad tadpoles with their kin is due to attraction rather than repulsion from non-kin. Experiments designed to elucidate the sensory basis of kin recognition showed that toad tadpoles recognize their kin based on chemical cues rather than visual cues. They can also discriminate between homospecific non-kin and heterospecific (Sphaerotheca breviceps) tadpoles since the tadpoles spent significantly greater amounts of time near the former than near the latter. These findings suggest that where kin members are unavailable, selection may have favoured living with non-kin so as to derive benefits from group living and that a phenotype-matching mechanism may operate for both kin and species discrimination in B. melanostictus.

Effect of lithium chloride on spermatogenesis, testicular delta 5- 3 beta- and 17 beta-hydroxysteroid dehydrogenase activities in toad (Bufo melanostictus)

Abstract: The purpose of the present study was to show the effects of lithium on testicular activities in the toad. Adult male toads were injected with lithium chloride (200 micrograms/toad) of alternate days for 21 days. At the moment of sacrifice on 22nd day, lithium treated animal showed decreases in testicular weight and Leydig cell nuclear area along with inhibition of spermatogenesis and testicular delta 5-3 beta as well as 17 beta-hydroxysteroid dehydrogenase activities. The results of our present experiment suggest that lithium administration might be associated with significant adverse effects on testicular activity in toad.

Survey of a population of Black-spined Toad Bufo melanostictus in Timor-Leste: confirming identity, distribution, abundance and impacts of an invasive and toxic toad

Abstract: EXECUTIVE SUMMARY IDENTITY All toads (945 individuals on 25.8 km of walked transects) observed in Dili, Liquica,Covalima (Suai), Manufahi (Same), Bobonaro and Oecusse districts were Black-spinedToad Bufo melanostictus . No Cane Toad B. marinus were recorded, and this species hasnot yet been recorded for Timor-Leste or Timor island. The Black-spined Toad issuperficially similar to the Cane Toad in appearance (and general ecology where known)and resources for the Timor-Leste government and other organisations to confidentlyidentify toads and other frogs are limited in Timor-Leste. ORIGINS The Black-spined Toad is native to Pakistan, India through to Indonesia. Populations aresilently invading eastern Indonesian islands (including Bali, Lombok, Sulawesi and Papua)through human transport. The international land border with Indonesian West Timor isentirely porous, and toad populations presumably entered from West Timor (or entereddirectly from boat transport originating from western Indonesia). The Black-spined Toadhas never been recorded on the Australian mainland, though a few individuals have beendetected on shipping containers by Australian Quarantine and Inspection Service (AQIS)entering Australia from eastern Indonesian. The Black-spined Toad is very poorly-studiedcompared to the Cane Toad, and its transport through the biologically diverse andendemic-rich Wallacean region (including Timor) is causing unnoticed and broad scalechanges to some biodiversity elements. Notably, a second species of invasive toad(Indonesian Toad B. biporcatus) has recently been recorded on Roti island off Timor. EXTENT OF THE POPULATION The Black-spined Toad occurs widely in western Timor-Leste (all districts, allanthropogenic habitats), and has been recorded as far east as Viqueque district. Populationsare invading faster, and occur at higher densities, along the higher rainfall south coast. Onthe north coast, toads are present in Dili (arriving about 2007), and are currently absentfrom Manatuto (town), Baucau and Los Palos. There are no reports yet from Atauro island. POTENTIAL POPULATION EXPANSION The Black-spined Toad tolerates a wide climatic range and is capable of establishing populations throughout Timor-Leste. Population growth and local establishment will beinfluenced by climate, availability of wetland sites for breeding, daytime shelter and food.Populations are likely to remain small along parts of the low rainfall north coast (e.g.Manatuto town c. 600 mm rainfall/year), and the tops of mountains will be sub-optimal (e.g. currently absent from mountain areas near Maubisse at 1,700 m). Toads are likely toreach the remaining eastern districts during the next 3-15 months (next 1-2 wet seasons). ENVIRONMENTAL AND OTHER IMPACTS The Black-spined Toad has toxins in parotid glands on its back. Frogs are widely eaten byvillagers in Timor-Leste, and at least one child has been killed, and many others have become sick after eating toads. The toad is a public health issue because local villagerslack knowledge about the toad’s toxicity. It is also a nuisance because toads can enter wells, drown and rot, potentially polluting important water sources. Road-killed toadswhich rot and smell will also be a nuisance particularly during the wet season. Wecollected qualitative data on the impact of the toads on Timor-Leste’s terrestrial biodiversity. Reportedly the Green Pit Viper Trimesurus insularis (a common poisonoussnake on Timor), the Timor Monitor Varanus timorensis (a small monitor lizard), other snakes, and quail/buttonquail species (small birds that nest on the ground) have declinedsince arrival of the toad. Preliminary observations suggest that populations of raptors (e.g.Brahminy Kite, Short-toed Eagle, Black Kite and Spotted Kestrel) have not been impacted.Some may not eat toads, while others are immune to the toxins. Populations of scincidlizards, geckos, land snails (including island endemics) and some other insect groups may be impacted by direct toad predation. Impacts to agriculture are poorly known – livestock such as buffalo, cattle, pigs, goats and chickens do not appear to be affected by toads.Recently hatched chickens (chicks) do die after ingesting toad toxin typically from road-killed toads. The impact of toads on crop pests (e.g. locusts, caterpillars) is unknown.Villagers indicated that toads ate the young shoots of maize, an important staple crop, butwe were unable to confirm this information. RECOMMENDATIONS • A public awareness campaign (radio, TV, poster/sticker, visits to all districts andAtauro island) is urgently needed (late 2009 and early 2010) to disseminateinformation to the public on the status of the toad, and particularly to warn villagersnot to eat toads because of its toxicity. It would be of value to disseminate informationon the design of wells to reduce Toad pollution/nuisance. • Survey of eastern districts (Manututo, Baucau, Viqueque and Lautem) and Atauroisland is needed to better understand the current status of the toad. • A fauna survey is needed to generate quantitative data on the impact of the toad on thehighly endemic and vulnerable island biodiversity of Timor-Leste including birds,mammals, reptiles, frogs, and some invertebrate groups. • Australian government (e.g. AQIS) to provide training/support in quarantine procedures for invasive toads and other to minimise the risk of invasive alien(non-native) species, including but not limited to Cane Toad and Indonesian Toad,entering the country. • Ministry of Agriculture and Fisheries to establish collaborative research programs withother research organisations to further develop research skills and generate reliableinformation on identity and status of invasive and native wildlife. • Prepare identification materials (or encourage international support for the generatingidentification materials and publication) for frogs and toads in Timor-Leste, whichwould be of value for public education and awareness, and identification during faunasurveys, impact assessments and Timor-Leste university research.

Effect of cold exposure on testicular Δ5-3β and 17β hydroxy-steroid dehydrogenase activities and plasma levels of testosterone in toad (Bufo melanostictus) in breeding and hibernating season: duration-dependent response

Abstract: The purpose of this study was to show the effect of cold exposure on testicular activities in breeding and hibernating seasons in the toad. Adult male toads were placed in a cold chamber in both breeding and hibernating seasons for periods of 7, 14 and 21 days. At the time of sacrifice on the 15th and 22nd days, cold-exposed animals showed a decrease in testicular weight, testicular delta 5-3 beta and 17 beta-hydroxysteroid dehydrogenase activities and low levels of plasma testosterone both in breeding and hibernating seasons. There was no significant alteration in the above mentioned steroidogenic enzymes and plasma levels of testosterone after 7 days of cold exposure, both in breeding and hibernating seasons in respect to the control animals. The results of our present experiment suggest that environmental cold is an important modulator of breeding activities in the male toad. It also indicates that the breeding and hibernating cycle in the toad (seasonal breeders) may be asynchronous to each other.