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Remember when I wrote about Panama disease, the fungal blight which is coming for the Cavendish bananas (after laying waste to the Gros Michel cultivar bananas back in the 50s)? Well, sadly, Panama disease is not the only apocalyptic fruit blight on the international circuit these days. It turns out that a bacterial disease is destroying citrus groves around the United States and beyond. The disease, known in English as “citrus wasting disease” is caused by a motile bacteria, Candidatus Liberibacter, which is spread by the Asian citrus psyllid (Diaphorina citri), an inconsequential Hemipteran insect which lives in citrus groves. There are multiple strains of greening disease, and there have been for a long time, but the newly problematic strain originated in China where it is known by the evocative name “huánglóngbìng” which means “Yellow Dragon Disease.”
The wild ancestors of most of today’s grape fruits, oranges, and lemons, came originally from the forests of East and South East Asia so it is not a huge surprise that this horrible disease comes from there too. Unfortunately hemipteran insects can easily proliferate in new ecosystems, so the disease became a problem after these invasive insect pests gained a widespread foothold throughout the semi-tropical regions where citrus is grown.
Citrus fruit is delicious and wonderful beyond compare…so it is worth big money. This means that agricultural scientists have been studying huánglóngbìng and attempting to stymy it with medicines, pesticides, and transgenic tinkering. The scientists themselves have been hampered in their research by the fact that it is hard to maintain and study citrus plants infected with the disease because they die so swiftly (the infected citrus plants, not the agricultural scientists). Powerful antibiotics work to wipe out the disease, but it is not practical to give these medicines to trees (though we will probably try—with predictable results). Scientists feel that there may be a transgenic solution, but it is unclear how marketable such a chimera will be (since protectionists and Luddites have been fear-mongering pretty hard against GMOs).
This leaves mass application of insecticide as the best bulwark against huánglóngbìng. It is starting to seem that small orchards and groves which are unwilling to commit to this kind of regimen will soon be gone. All of this strikes me as unbearably sad and frightening. Why are there so many blights everywhere? Has this always been a peril of agriculture (indeed of life?) or has contemporary monoculture paved the way for widespread proliferation of these superbugs? There must be some parasitoid wasp or something which has kept these damn psyllids from wiping out species citruses of wild Asia. Maybe we could bring that here…but it probably would cause some new horrible problem.
We’ll keep you posted. In the meantime you should glut yourself on oranges this winter…while you still can.
Kindly accept my apologies for not writing a post yesterday. I am traveling the Great Lakes and Canada and will try to update when I am able. Today I am in Chicago. As I was looking out at Lake Michigan, I wondered whether there were any catfish native to the vast body of water– which is so large it might as well be considered a freshwater sea.
As it turns out the lake is home to channel catfish (Ictalurus punctatu), the quintessential North American siluriform. The channel catfish is a hardy omnivore which dwells in rivers, lakes, and ponds from southern Canada to northern Mexico. They eat smaller fish, arthropods, worms, seeds, and just about any other edible thing which will fit into their mouths. Channel catfish are nest breeders. If the female catfish is unable to find a promising crevasse in which to lay her eggs, the male will arrange logs and rocks into a nesting bed for her. He then guards the eggs until they hatch and even stays with the fry while they are very small (although if he is unduly disturbed he might eat the eggs and start all over again!).
While the channel catfish are hardly as flashy as some of the exotic catfish we have covered here, they are vastly successful organisms. They can also grow to be fairly large and specimens measuring up to 23 kg (50 pounds) have been caught (although such giants are quite old and rare). Although the catfish live naturally in Lake Michigan, they are also raised on farms throughout the American south (indeed they are the “Delecata” mentioned in this post about international catfish trade wars). Channel catfish have been introduced in parts of Europe, Malaysia, and Indonesia, where they are now causing havoc among native species.
But Channel catfish here in the Great lakes are facing their own invasive threats. Lake Michigan has been colonized by wave after wave of invasive animals. Some, like the omnipresent zebra mussels, are harmless to catfish (albeit infuriating to humans). Others like the sea lampreys (Petromyzon marinus) are not so benign for catfish. The jawless lampreys are vampires which attach to the bodies of catfish (and a wide variety of other native Great Lakes fish) and then rasp a hole in the hosts’ sides by means of sharpened tongue. Even more alarmingly, the leaping thriving all-devouring Asian carp has been making its way up Illinois’ rivers towards Lake Michigan. The state has been trying to prevent these dangerous fish from getting to the Lake by means of increasingly horrifying devices and stratagems such as underwater electric fences and mass poisonings. So far it has been working but there is still an underwater war raging for Lake Michigan.
The world’s largest hornet is the Asian giant hornet (Vespa mandarinia). An individual specimen can measure up to40 mm (1.6 inches) long with a wingspan of 60 mm (2.5 inches). Giant hornets have blunt wide heads which look different from those of other wasps, hornets, and bees and they are colored yellow orange and brown.
The Asian giant hornet ranges from Siberia down across the Chinese coast into Indochina and lives as far west as India, however the hornet is most common in the rural parts of Japan where it is known as the giant sparrow bee. The sting of the Asian giant hornet is as oversized as the great insect is. Within the hornet’s venom is an enzyme, mastoparan, which is capable of dissolving human tissue. Masato Ono, an entomologist unlucky enough to be stung by the creature described the sensation a “a hot nail through my leg.” Although the sting of a normal honey bee can kill a person who is allergic to bees, the sting of an Asian giant hornet can kill a person who has no allergies–and about 70 unfortunate souls are killed by the hornets every year.
Armed with their size and their fearsome sting, Asian giant hornets are hunters of other large predatory insects like mantises and smaller (i.e. all other) hornets. The giant hornets do not digest their prey but masticate it into a sticky paste to feed to their own offspring. A particular favorite prey is honey bee larvae, and since European honey bees have no defense against the giant wasps, all efforts by Japanese beekeepers to introduce European bees have met with failure. Japanese honey bees however have evolved a mechanism (strategy?) to cope with hornet incursion. When a hive of Japanese honey bees detects the pheromones emitted by hunting hornets, a crowd of several hundred bees will form a gauntlet (carefully leaving a space for the hornet to enter). Once the hornet walks into the trap the bees rush on top of it and grasp it firmly. They then begin to vibrate their flight muscles which raises the temperature and produces carbon dioxide. Since giant hornets cannot survive the CO2 levels or high temperatures that honey bees can, the hornets put up a titanic struggle to overcome the mass of bees, killing many in the process. However honey bees have a fanaticism which would do credit to the most ardent practitioner of Bushido, and they usually kill the invaders.
Continuing our series of posts about saber toothed mammals we come to a second family of living creatures. Half way between the primitive chevrotains (mouse deer) and the familiar true deer (cervids) are the Moschidae, a family of small artiodactyls consisting of one genus with several similar species. The musk deer are small delicate grazers which live in the forested mountains or alpine scrubland of Asia. Musk deer weigh between 7 and 17 kilograms (15 and 37 lb) depending on gender, age, and species. Unlike true deer, the little creatures lack antlers, but male musk deer make up for this absence with a pair of elongated canine teeth which they use to fight for breeding rights.
Like true deer, musk deer eat the tender shoots of trees and grasses, as well as berries, lichens, and mosses. Females live in small territories of approximately 100 to 200 acres. The territory of a dominant male will overlap several of the females’ territories. Female musk deer give birth to a single fawn. Musk deer are nocturnal or crepuscular. They use their acute hearing and excellent sense of smell to flee from predators at the slightest hint of danger.
Male adult musk deer have a musk pouch located between their genitals and their umbilicus which they use to attract mates. Unfortunately for the little saber toothed deer this pouch also attracts human hunters. For centuries (or longer) musk has been a prized luxury good, so much so that, at times, prices have soared to $45,000/kg on the black market. The musk is said to have an incredibly complex aroma but the main notes are earthy, woody, and “animalic” (i.e. fecal). Dried musk grain must be substantially tinctured with alcohol before it produces a perfume which is pleasant to humans. The resultant substance however served as a mainstay of the perfume industry and as a cure-all nostrum in ayurvedic medicine until the creation of synthetic musk. Poor musk deer from several species were nearly wiped out because of whatever mysterious power their sexual marking fluid has on humankind.