New Phelsuma klemmeri

Here's what was waiting for me when I got home from work on Friday:

These are not for sale, sorry.

Tiger salamanders, fishing bait and chytrid

The commercial trade of wildlife occurs on a global scale. In addition to removing animals from their native populations, this trade may lead to the release and subsequent introduction of nonindigenous species and the pathogens they carry. Emerging infectious diseases, such as chytridiomycosis caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), and ranaviral disease have spread with global trade in amphibians and are linked to amphibian declines and die-offs worldwide, which suggests that the commercial trade in amphibians may be a source of pathogen pollution. We screened tiger salamanders involved in the bait trade in the western United States for both ranaviruses and Bd with polymerase chain reaction and used oral reports from bait shops and ranavirus DNA sequences from infected bait salamanders to determine how these animals and their pathogens are moved geographically by commerce. In addition, we conducted 2 surveys of anglers to determine how often tiger salamanders are used as bait and how often they are released into fishing waters by anglers, and organized bait-shop surveys to determine whether tiger salamanders are released back into the wild after being housed in bait shops. Ranaviruses were detected in the tiger salamander bait trade in Arizona, Colorado, and New Mexico, and Bd was detected in Arizona bait shops. Ranaviruses were spread geographically through the bait trade. All tiger salamanders in the bait trade were collected from the wild, and in general they moved east to west and north to south, bringing with them their multiple ranavirus strains. Finally, 26-73% of anglers used tiger salamanders as fishing bait, 26-67% of anglers released tiger salamanders bought as bait into fishing waters, and 4% of bait shops released tiger salamanders back into the wild after they were housed in shops with infected animals. The tiger salamander bait trade in the western United States is a useful model for understanding the consequences of the unregulated anthropogenic movement of amphibians and their pathogens through trade.

Amphibian Commerce as a Likely Source of Pathogen Pollution. Conserv Biol. 2008 Aug 19

Can you turn fruit flies into calcium pills?

A while ago, I wrote about Why do frogs need vitamins:

Animals also need a range of minerals, one of the main ones being calcium (for bones and the nervous system). Insects don't have bones, and compared with vertebrates, they have a reversed calcium:phosphorus ratio, i.e. they contain more phosphorus than calcium, whereas in animals, it's the other way round. Most insects are therefore a poor source of calcium, although soil arthropods such as springtails and woodlice may contain reasonable amounts.

On Frognet recently, Ed Kowalski pointed at an interesting scientific paper I hadn't seen before, in which scientists kept Drosophila melanogaster on low and high calcium diets to see if this increased the calcium content of the flies. To cut a long story short, the answer is no:

Flies were raised on the standard calcium diet and then transferred to either the high calcium or low calcium diet within 24 h of emergence. Calcium contents of whole flies and tubules were measured for 10 days after transfer, and calcium contents of whole flies of the resulting F1 generation were determined at intervals for 15 days after emergence. The flies maintained a calcium content of ~4.4 nmol/fly for 10 days after emergence; there was no increase in calcium content with time after transfer to high calcium diet.

However, they did find that:

Although larvae weighed 2X as much as adult flies, they contained 3–4X as much calcium.

Unfortunately, these amount of calcium are low, probably not enough to satisfy frog's needs. When the levels of calcium are high enough to ensure a positive calcium to phosphorus ratio of at least 1:1 and ideally closer to 1.5 to 1, the mortality of the insects increases rapidly. So we still need to supplement feeder insects with calcium (and other minerals and vitamins).

Related: Tip of the Day: Feeding Drosophila larvae


Calcium homeostasis in larval and adult Drosophila melanogaster. 2000 Archives of Insect Biochemistry and Physiology
44: 27-39
Calcium homeostasis in Drosophila melanogaster was examined in response to the challenges imposed by growth, reproduction and variations in dietary calcium content. Turnover time for calcium, calculated as the time for Ca to accumulate to half the steady state value of 3.46 nmol/fly, was 3.3 days. Although larvae weighed 2X as much as adults, they contained 3–4X as much calcium. Anterior Malpighian tubules (MTs) contain much more calcium than posterior MTs, accounting for 25–30% of the calcium content of the whole fly. In response to a 6.2-fold increase in dietary calcium level, calcium content of whole flies increased only 10%. Hemolymph calcium concentration (~0.5 mM) was similar in males and females and in animals raised on diets differing in calcium content. Fluid secretion rate, secreted fluid calcium concentration, and transepithelial calcium flux in tubules isolated from flies raised on high and low calcium diets did not differ significantly. Malpighian tubules secrete calcium at rates sufficient to eliminate whole body calcium content in 0.5 and 3 days for tubules secreting fluid at basal and maximal rates, respectively. It is suggested that flies absorb high quantities of calcium from the diet and maintain homeostasis through the combined effects of elimination of calcium in fluid secreted by the Malpighian tubules and the sequestration of calcium in granules, especially within the distal segment of the anterior pair of Malpighian tubules.

Neurergus kaiseri colour patterns

Coen Deurloo has two groups of juvenile Neurergus kaiseri, one from me and one from another breeder, and he sent me an interesting set of photos showing consistent pattern variation between the two groups:

I'm not sure how significant this is as the colour pattern on these animals changes significantly as they age, the adults having less spots and more blocks of black and white, so I think that the spotted animals are slightly less mature (although they are a similar age) to the others?