Honey bees are not native to the Americas. During the 1600's, settlers brought honey bee colonies with them from Europe, hence the name European honey bees (EHB). In South America, honey was becoming an important industry, and so EHB were imported on to farms. However, their production was not satisfactory, so they looked for other species. In 1956, geneticist Warwick Kerr was sent by the Brazilian government to Africa to collect African honey bee queens. He brought back 63 queens, but only 48 survived. Kerr began doing breeding experiments with them, and, by interbreeding the queens with EHB drones via artificial insemination, the Africanized honey bee (AHB) was born in Piracicaba and Rio Claro, Sao Paulo, Brazil. 29 were born in all. AHB and EHB may be similar in appearance, but not in behaviour. AHB will attack when unprovoked, and, although their venom is not quite as potent as that of the EHB, can kill grown humans because they respond in larger numbers and will pursue for longer distances. One bee can produce 0.1 mg of venom, the same as that of the EHB.They were placed in a box with queen excluders that allowed only the smaller workers to fly out so that they would not reproduce in the wild, and honey was soon made. In 1957, a local beekeeper noticed the excluders and removed them, trying to be helpful as it wasn't the season for excluders to be used. 26 AHB queens escaped and began to rapidly reproduce in the wild. They are highly aggressive and will attack any living thing that comes within 50 ft of their nest, or any power equipment that comes within 100 ft. They will pursue a person for 1/4 mile, allowing time for many hundreds of bees to sting. When they sting, both the stinger and the venom sack are ripped from the bee's body, killing it instantly. The venom enters the bloodstream, but is so small in amount only repeated stings will do much harm. When the stinger is ripped out, high concentrations of a pheromone known as iso-pentyl acetate are deposited. This acts like a beacon for other bees and communicates to them to sting. More bees sting: more pheromone is released. More pheromone is released: more bees sting. Although they have accounted for only 7 human fatalities in the US, 175 fatalities have been reported in Mexico alone since 1985. This does not include livestock fatalities, of which there are many.Since their introduction into Brazil, they have killed some 1,000 humans. Warwick Kerr was not worried and assumed that they would mate with other EHB bees and eventually lose their African honey bee side. However, they did not, and reports of feral bees attacking livestock began to pour in. The first Africanized honey bee colony found in the US was reported on October 15, 1990, at Hildago, Texas, very near the Mexican border, progressing some 100 to 200 miles per year. In May of 1991, Jesus Diaz became the first bee sting victim of these "new" bees. He suffered 18 stings. The first death occurred on July 15, 1993, when Lino Lopez, 82, was stung 40 times while attempting to remove a colony from a building's wall. Since then, many more cases have been reported as they spread throughout the US. Today they are found in 110 counties in Texas, 14 counties in Arizona, 7 counties in New Mexico, 1 county in Nevada, and 3 counties in California. Scientists believe they will continue to spread throughout the southern US. The main enemy of the AHB is the EHB in that they must compete for food and nesting areas. They are also eaten by birds, dragonflies, and other insects.
- moths
- Euproctis chrysorrhoea (browntail moth) : simply touching a caterpillar which grows into the browntail moth triggers a severe rash, skin welts and respiratory attacks, and has left 2 researchers dead in the last century. Native to certain regions of Europe, the browntail moth sailed into Boston with the ornamental rose trade in the late 1800s. Lacking many natural predators, it quickly spread in the north-eastern states and stripped trees of their foliage, before mysteriously shrinking back to a few coastal pockets by the 1930s. In the last few years, however, the caterpillar has again reared its head, venturing periodically into Portland, Maine, and the forests of Cape Cod, and raising fears that it will spread further because pesticide use is prohibited in protected forests. Baculovirus naturally infects and kills browntail moth caterpillars in Europe : researchers have previously struggled to grow this virus because they had to collect it from the toxic creatures in summer while wearing protective suits. Around 50-80% of the moths were killed by the virus within weeks. Should the preliminary trials hold up, he hopes the virus could be mass produced as an alternative to the harsh pesticides that kill many moth species. It might also treat periodic outbreaks of browntail moth in Europe. Releasing a virus to combat a moth may raise environmental concerns, as it could infect other species with unknown consequences, but the virus did not infect close moth relatives in the lab and it appears to be activated only by a particular food in the browntail moth's gut
- Lymantria dispar (gypsy moth) in US forests
- Magicicada (periodical cicadas) : worldwide there are about 3,000 cicada species. Many emerge in the spring, but only Magicicada are officially designated periodicals: cicadas that have an exact-length life cycle and perfectly synchronized emergences. The definition is a bit of a semantic question. Even the so-called annual cicadas, also known as dog-day cicadas because they emerge in late summer, may be in a sense periodical. Their life cycle is uncertain, but that nightly cacophony heard in August is not from the cicadas laid as eggs the past summer. There are 3 groups of Magicicada (decim, decula, and cassini, comprising 7 known species in the Eastern USA), that differ in behavior, appearance, songs (the typical decim chorus has a dominant pitch at around 1.3 kHz), and genetics. Each group has 1 species with a 17-year life cycle and at least 1 that lives 13 years. Periodical cicadas in different regions come out in different years. Each year-class or brood is designated with Roman numerals; this year's is Brood X. Most broods contain members from all three groups. 12 broods are 17-year cicadas and live mostly in the northern United States and the Great Plains; 3 broods live 13 years, mostly in the South and Midwest. In the eastern United States a troop of cicadas known as Brood X is back for another breeding season : the army emerges without fail every 17 years after feeding on underground roots. For the next few weeks, the locust-like insects will infest huge swathes of land encompassing Washington DC and Baltimore, as well as much of Kentucky, Tennessee, Cincinnati (Ohio) and Indiana. When the insects appear, the adults burrow up from the soil to mate, then lay their eggs inside trees, allowing newborn larvae to travel back underground. Once the mating season ends, these adults die and their bodies litter the forest floor. It is hard to say how many foot-soldiers will make up the invasion, but there will definitely be billion : in affected areas, around 100 insects emerge from each m2 of ground, although this number can vary from fewer than 10 to more than 300. Although they aren't welcome in the cities, the nutrients from the Magicicada carcasses provide a valuable boost to forest ecosystems. Scientists had already noticed that in the years following the cyclical emergence of the cicadas, forest plants seem to have unusually high amounts of nitrogen in their leaves, normally a limiting factor in the plants' growth.. A month after adding 140 cicada carcasses per m2 of ground to a plot that contained a forest plant called the American bellflower (Campanulastrum americanum), the numbers of bacteria and fungi known to feed on biological material in the soil had been boosted, and the amount of ammonium and nitrate available for plants to use had increased by up to 3 times. The plants later had 12% more nitrogen in their leaves, compared with plots without cicadas, and produced seeds that were 9% larger. Similar 'resource pulses' are seen in other ecosystems, he points out, including dramatic plant growth after El Niño rainfalls, and the nutrient boost to riverbank communities when large amounts of salmon die after spawning. Adventurous restaurateurs will have some interesting additions to their menus. And the artistically minded might be inspired by the cicadas' whirring song, as was Bob Dylan (even though he misnamed the insects) in his 1970 song Day of the Locusts. For researchers the event will be a valuable chance to learn more about these animals, whose lifestyles make them notoriously difficult to study : the fact that they spend so many years underground makes it impossible to keep them in a lab. There are > 12 separate groups, or broods, of periodical cicadas buried snugly across the eastern United States. Each has a different cycle that sees them emerge every 13 or 17 summers. After mating, the adults slit open a nearby tree and lay their eggs inside the bark, leaving the newborn larvae to make their way underground. Experts are still puzzled as to why the cycles are exclusively prime-numbered. The oldest theory is that cicadas with even-numbered cycles were wiped out by predators that had shorter population cycles, which allowed them to fall into synch with the insects, but cicadas' predators, which include household pets, are unfussy eaters, so this is unlikely. More probable is the idea that long, prime-numbered cycles ensure that the broods breed with their own kind. Hybrids of different broods rarely survive to breed in the next emergence. Switching between different cycle lengths may even cause broods that live in the same area to become separate species. A simple developmental switch that adds 4 years to the 13-year growth period has been discovered, and whether 13- and 17-year cicadas that emerge during the same summer are able to interbreed is object of study. Such 'natural experiments' compensate for the impossibility of rearing cicadas in the lab. The sheer numbers of Brood X should make them a valuable research tool, but researchers are not getting too excited just yet. Some fear that the urban development of the past 17 years may have trapped many cicadas under pavements, car parks and buildings… creating a true underground army. 2005 and 2006 are cicada-free, but in 2007, 17-year Brood XIII will command attention as it appears around Chicago. Periodical cicadas survive via predator satiation : they combine the idea of safety in numbers with the idea of not being around for a long period of time. Satiation as a strategy makes speciation difficult : individuals pioneering a new trait are few in number; chances are they would be picked off quickly and fail to pass on the traitref1, ref2. Periodical cicadas seem to have flexibility in their life-cycle length that is environmentally triggerable, or can be environmentally cued. By mating time, so many cicadas flight into the area that cicada choruses are measured at 96 dB (hearing damage can occur at 93 dB)
- Anoplolepis gracilipes (yellow crazy ants), so-called because of their chaotic movements, are one of the world's most invasive species. The ants have lost the ability to form queens that fly away from the parent colony to form new communities elsewhere. Instead they form dense supercolonies as their numbers increase, with up to 1,000 ants per square kilometre of bush. The ants were first spotted in northern Australia in 1990, but their numbers have been rising rapidly in the past few years. In Australia's northeast Arnhem Land, the insects have now infested 25,000 square kilometres of land - feasting on the local flora, and killing or out-competing resident invertebrate populations. Several years ago crazy ants invaded one of the 4 locations where the gove crow butterfly (Euploea alcathoe enastri) was thought to exist, and since then the butterfly seems to have gone locally extinct. The ants spray formic acid into their victims' eyes, blinding them and causing them to starve to death. As the ants' activities change the local flora and fauna, larger animals such as wallabies and possums could struggle for survival and humans might also suffer as ants and aborigines share some of the same resources, such as berries. Researchers plan to combat the ants by dropping granules of a specially designed poison onto 75% of the colonies from helicopters within a year. The pellets, called Presto, contain a fishmeal product that ants love, but that other animals detest. The poison has already yielded encouraging results on Australia's Christmas Island, where the ants have destroyed up to 20 million red land crabs (Gecarcoidea natalis) since 1989, triggering a 30% decline in the crab population. The approach brought the crazy ant population under control, while other animals have remained unaffected. Yellow crazy ants are thought to have originated in Africa, then made their way to Asia and the Indo-Pacific hidden in packing materials and crates. Researchers suspect they first arrived in Arnhem Land during the Second World War, when American ships made frequent trips between Australia and the ant-rich South Pacific islands.
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Schistocerca
gregaria (Forskal) (African desert locust) is a type
of grasshopper that usually lives in the deserts of Africa and Asia. The
insects emerge from eggs laid in sandy soil, develop into wingless 'hoppers'
on the ground and then mature into winged locusts. When the insects are
sparse, they act autonomously, but when they build up a critical mass,
they change colour and start acting together, forming moving carpets of
'hoppers' and then winged swarms that can span several hundred square kilometres.
A swarm can consume the same amount of food in one day as several thousand
people. Widespread swarms, called plagues, occur sporadically and
have been reported since ancient Egyptian times. 2 days of torrential rains
in western Africa in October 2003 encouraged the insects to breed, as it
provides them with green vegetation to feed on and damp sandy soil in which
to lay eggs. Each time the insects spawn a new generation, which they have
done at least 4 times since last October to August 2004, their numbers
swell by a factor of about 20. They later moved northwards to Morocco,
Algeria, Tunisia and Libya. In 2004, favourable weather conditions have
vastly increased their numbers. Despite efforts to control them, the first
swarms are forming and heading back to northwestern countries, including
Mauritania, Senegal and Mali. The locusts are soon expected to spread east
towards Niger, Chad and Sudan. So far, the scale of the infestation is
on a par with the growth of the last plague in 1987-89, which affected
28 countries. Part of the reason that the previous plague ended in 1989
was simply because freak winds gusted swarms out into the Atlantic. The
worst-case scenario is that they will strip subsistence crops in areas
that are already suffering severe food shortages because of civil war or
drought. Locusts are mainly curbed using insecticides
,
such as the organophosphate malathion, which is sprayed from vehicles and
aeroplanes. Unfortunately, this kills insects and the toxin can accumulate
in birds, lizards and other animals that feed on the poisoned insects.
An alternative, but still experimental, way to combat the desert locusts
is with spores of a Metarhizium fungus that infects and kills the
insects : it has been tested against a related species of locust in areas
of Australia where there are endangered birds, livestock or organic crops.
But there are downsides: the fungus costs more than conventional pesticides;
takes a week or 2 longer to kill; and the infrastructure is not present
to produce large enough quantities to fight the swarms that may shortly
descend. One of the hardest things is tracking down the bands of hoppers,
which cover just a few square metres, in several hundred square kilometres
of desert. This requires countless aeroplanes and cars. Research into alternative
methods has dried up, because interest has died since the last plague.
Another problem is that vital information may not be shared, because some
of the northern African countries are reluctant to admit holes in their
control policies. The 1987-89 plague cost more than US$300 million to quell,
and this time experts say there are critical shortfalls in the stock of
pesticides available and in money to buy more. The FAO says it needs an
extra $10 million to $20 million for this summer and autumn and is calling
on donor agencies to cough up more money, but it has to compete with other
humanitarian demands. Whether the early swarms develop into vast ones partly
depends on the weather: rains will escalate the problem and dry weather
could assuage it. But some say that a plague is almost unavoidable without
drastic intervention. In October-November 2004 winds carried them from
summer breeding grounds in Mali and Niger towards the Mediterranean coasts
of Libya and Egypt, and even to the islands of Crete and Cyprus. Locusts
have not moved this way, from northwest to southeast, since the 1950s.
On 17 November, a large swarm filled the midday sky above Cairo in Egypt;
days later, remnants of the same swarm hit the northern Red Sea, including
the beach resort of Eilat in southern Israel. Although some fear that the
Red Sea insects may breed, the thickest swarms (and those of most concern)
are moving north into Morocco and Algeria, where they will probably grind
to a halt during the cold, dry winter months. After this, there are 2 possibilities
: in the most optimistic scenario, the spring rains fail and deny the insects
the opportunity to breed by laying their eggs in damp soil. This, along
with continued efforts to crush the insects with pesticides, could bring
the situation under control. The worst case scenario is one in which ample
rains spur bountiful breeding and swarms emerge in greater numbers next
spring to re-invade western Africa. - In Australia, meanwhile, experts warned this week of an imminent attack on crops by the Australian plague locust (Chortoicetes terminifera). The current wet weather means that the insects' could conceivably reach plague levels, as they last did in 1987. The insects developed after heavy rains in parts of southern Queensland and northern New South Wales in January, and laid eggs that are expected to hatch shortly.
Web resources : browntail moth
Web resources :
red = swarms; yellow = bands; blue = adults; green = hoppers
Web resources :
