Pacific Island Ecosystems at Risk (PIER)

The Pacific Island Ecosystems at Risk (PIER) website is an excellent resource to the weeds of importance throughout the tropical Pacific region. The main strength of the site is the extensive list of species fact sheets (including Sphagneticola trilobata, an important lowland weed in Western Viti Levu, Fiji; pictured above) It also includes assessments of the weed fauna of several Pacific Islands, primarily within Micronesia and Polynesia.

While on the subject, SPREP has published some guidelines for the management of invasive species in the Pacific, an important document for those dealing with such things in the region.

Featured insect: Pantorhytes plutus (Coleoptera: Curculionidae)

The weevil genus Pantorhytes is a large genus placed in the tribe Pachyrhynchini in the subfamily Entiminae. It consists of over 74 species found primarily in New Guinea, but also being found in the Solomon Islands and Queensland. The species pictured here, P. plutus is found in the Bismarck Archipelago. A map showing the distribution of specimens in the Australian National Insect Collection (see here also) can be found here

Pantorhytes plutus and a number of other species in the genus have become major pests of cacao trees, particularly in PNG. All the species have fairly limited ranges, such that P. szentivanyi, P. albopunctulatus and P. healyi are pests in the Northern Province of PNG, P. torricellianus is a problem in the Sepik region, P. plutus through the Bismarcks, and P. biplagiatus through Bougainville and the Solomon Islands. The genus has had a surprisingly large amount of study done on their biology, including egg development, and control. A couple of studies have looked at their dispersal, including one study that used a radioactive isotope tracing technique, which provided theoretical insight into mathematical models of insect dispersal. A parasitic wasp, Pristocera rufa is known to parasitize P. szentivanyi, though not to such an extent as to be a reliable biological control agent.


They are such a threat, they have made it onto a page detailing the world's worst cocoa problems (though I cannot find any other evidence that Pantorhytes are in Tuvalu), and accordingly there's been a number of studies dealing to their control (such as this one and this one).Biopesticides, including Beauveria bassiana have also proved to be of use in their control. A photo of an infected beetle is shown above.

A circular detailing their control in the Solomon Islands recommends using ants as a form of biological control. Unfortunately, two of the species they recommend for this control are the yellow crazy ant (Anopolepis gracilipes) and the little fire ant (Wasmannia auropunctata). Both these species are highly invasive generalist predators and scavengers which have adverse effects on more than just Pantorhytes weevils in cacao plantations. Should they already be present in the area, their use as a control agent may be encouraged, but they should NOT be introduced anywhere for that purpose if they aren't already there.

References:
Gressitt JL. 1966. The weevil genus Pantorhytes (Coleoptera) involving cacao pests and epizoic symbiosis with cryptogamic plants and microfauna. Pacific Insects 8(4):915-965.
Setliff GP. 2007. Annotated checklist of weevils from the Papuan region (Coleoptera: Curculionoidea). Zootaxa 1536. 296pp.
Stibick JNL. 1978. The genus Pantorhytes (Coleoptera: Curculionidae) Division A. I Addistions and changes to the common and major cacao species. Pacific Insects 18(3&4):115-136.

A mystery... scale insects on European manuka

Manuka (Leptospermum scoparium) is native to New Zealand and southeast Australia. It is common throughout New Zealand and is well known for being the source of manuka honey which is sought after for its healing properties, and for being a good source of firewood (particularly for smoking fish). Its trait of having numerous white flowers has also ensured that it is fairly commonly grown as a garden plant, and so has been exported around the world for this purpose.

So when a scale insect that apparently is specific to the plant is found in Italy and Corsica in 2004 and 2006, one would imagine that it came from New Zealand or Australia right?

Acanthococcus mariannae was described yesterday in a Zootaxa paper by Giuseppina Pellizzari and Jean-François Germain. The 30 or so specimens that went into the description were all collected from manuka from Italy and France. Surprisingly though, despite the author's (reasonable) assumption that the insect was introduced to these countries on the plants, this species has not (yet?) been found in either New Zealand or Australia. Moreover, specialists familiar with scale insects in these countries had not noticed it before. While it is likely that further searching will reveal it on manuka in NZ or Australia. However there is the lingering question: if it's not, where did it come from and how has it started attacking manuka?

Scale insects aren't glamorous. They are little more than a bag of fluid that get sap pumped into them. But they are important in a properly functioning ecosystem; and when they get out of control the consequences can be severe. This can be illustrated by an example that also involves manuka: the incidence of manuka blight in New Zealand in the 1940s and 1960s.

Manuka naturally harbours large numbers of the scale insect Coelostomidia wairoensis which produces a lot of honeydew. This in turn provides a food source for the sooty mould Capnodium walteri which covers the branches of manuka forming thick, black deposits.

In the late 1930s manuka in Canterbury (South Island of New Zealand) started to grow sick and die. By the late 1940s it was reported that it was hard to find living manuka in the region. Farmers assisted in the spread by moving infected manuka around the country to control what they viewed as a weed. The culprits were found to be two species of Eriococcus scale insect that presumably had been introduced from Australia. The effect on the plant appears to be due to nutrient stress from having large numbers of scale insects sucking on it as opposed to being a disease transmitted by the insects.

In 1957 it was discovered that a fungus was killing E. orariensis, the species that damaged manuka most severely. Subsequently, the numbers of this scale insect declined dramatically with a corresponding increase in manuka numbers. Manuka has also seen a rise in popularity and is no longer viewed as being as significant a weed.

References:

Epenjijsen CW, Henderson RC, Carpenter A, Burge GK. 2000. The rise and fall of manuka blight scale: a review of the distribution of Eriococcus orariensis (Hemiptera: Eriococcidae) in New Zealand. New Zealand Entomologist 23: 67-70.

Pellizzari G, Germain J-F. 2010. A new species of Acanthococcus (Hemiptera, Coccoidea, Eriococcidae) on Leptospermum scoparium (Myrtaceae) from Italy and France. Zootaxa 2543: 51-63

Fire ant origins and genetics

The fire ant Wasmannia auropunctata is one of the most annoying things in the Solomon Islands. They have a very irritating and itchy bite, are so small as to be invisible, and they have a penchant for living in your underwear draw. Not pleasant. Unfortunately, they are another of the invasive species that have invaded the islands from elsewhere, in this case South America. They are found naturally through a large part of South America, from Argentina to the Caribbean islands. They have been introduced to a number of places, including Hawaii and the United States, Gabon in West Africa, and in the South Pacific both the Solomon Islands and New Caledonia.

To investigate where these ants came from, Alexander Mikheyev and Ulrich Mueller conducted a genetic study on a bunch of both natural and introduced populations of the fire ant. Looking at a little bit of the mitochondrial COI gene, they discovered that the Solomon Island populations have affinities with US and Hawaiian, and Northern South America and Caribbean populations. New Caledonian specimens were quite different, originating from southern natural populations in Argentina and Brazilian populations. Gabon has also been invaded by this group. This suggests that the two Pacific populations sampled were independantly derived, probably through trade or troop movements during WWII.

An assumption that I've usually made with invasive species in the Pacific is that they tend to do a bit of island-hopping, and in this case I would've hypothesised that the New Caledonian and Solomon Island populations would be the same. This is obviously not the case here, and it is a reminder that it's worth keeping in mind that there are many ways for organisms to get from place to place.

References:
Mikheyev AS, Mueller UG. 2007. Genetic relationships between native and introduced populations of the little fire ant Wasmannia auropunctata. Diversity and Distributions 13:573-579.

Tokelau Ant Communities

Tokelau is a small place, far away from anywhere. Unfortunately, like all Pacific Islands, it has been overrun by invasive ants, which have massive impacts on the ecosystem of the islands. Phil Lester and his crew from Victoria University in Wellington, New Zealand made the most of a bad thing and took the opportunity to investigate community structure and assembly processes on these islands. What they did which few others have done was investigate the effect of abundance on community assembly, as opposed to just recording which species are found in the same places as each other. As expected, they found that as the abundance of ants went up, the number of species present decreased.

The ant that was dominant, was the yellow crazy ant, Anoplolepis gracilipes. And boy, was it dominant! Maximum abundances were 100 times that of the most abundant species. Rather unsurprisingly, the authors comment that

"in high abundance, A. gracilipes was associated with reductions in the number of co-occurring species and their abundance."

In this research, the authors only looked at the effect on other ant, which are also introduced to Tokelau. However, the effect of the ants can be devestating. One of the most publicised crazy ant invasions is their effect on the ecosystem of Christmas Island, Indian Ocean, home to the charismatic red land crab. A couple of reports about the invasion in the popular press are this one from the ABC and a report from the Australian Government

Reference:
PJ Lester, KL Abbott M Sarty and KC Burns. 2009. Competitive assembly of South Pacific invasive ant communities. BMC Ecology 9:3

ACIAR publications

The Australian Centre for International Agricultural Research, better known as ACIAR publish a range of books dealing with crop protection, animal husbandry and other aspects of agriculture. They have a strong Southeast Asia and Pacific focus. Even better, many of their books are available for free downloading from their website.

Some of the selection includes:
TaroPest: An illustrated guide to pests and diseases of Taro in the South Pacific
A diagnostic field guide for one of the most iconic and staple foods of the Islands

Gardens of Oceania
A summary of gardening practises in the Pacific (Vanuatu in particular) plus descriptions of the plant species grown and notes on their uses.

and
Guidelines for Survelliance of Plant Pests in Asia and the Pacific
A good overview of the steps to developing monitoring and detection surveys. Unfortunately, the sections on analysing and reporting are rather scant. This is a shame because in my experience, this is where the professionalism of South Pacific science tends to tail off. Collecting data is great, but to go the whole distance, it needs to be analysed and published.

There is also an interesting quirk in the typesetting of the book in that the string "fi" does not show up. A bit annoying when dealing with the "Paci c" region and telling people about "con dence" intervals.

These criticisms aside, it's great that these very informative and helpful publications are available freely online. May the good times continue!

Lots of undescribed species!!!

This August, a seminal paper was published by the Entomological Society of New Zealand's news bulletin The Weta. I am of course, talking about the note entitled "Insects associated with the mature seedheads of Buddleja davidii Franchet (Scrophulariaceae)" written by yours truly. It is my first entomological paper of sorts, and as such I am relatively pleased with it.

It came about when doing some work to finish off my undergrad degree and I ended up seiving some buddleja seedheads to get the seeds. I was surprised to see lots of insects in the seedheads and so I decided to keep them and identify them for my own interest. What interested me most was the diversity of insects, particularly ones which are considered to be native to New Zealand. You tend not to expect such high numbers of indigenous species on introduced weeds. At least I didn't.

The other things which really interested me was finding three undescribed wasp species. This really brought home to me how much we don't know about the world around us. It also gave me an interesting story to tell people who express surprise when I tell them that there are still lots of insects to describe.

For a paper that was somewhat of an afterthought, it's not too bad I reckon. Let me know what you think though....

Featured Insect: Oryctes rhinoceros Linnaeus, 1758 (Coleoptera: Scarabaeidae)

The coconut palm (Cocos nucifera) is one of the quintessential plants of the South Pacific and its prominence in the lifes and history of the islanders cannot be overestimated. Coconut palms and their products, while not quite as all-encompassing as they used to be, remain a vital food source and cash crop for a large number of people around the world.

Coconuts have many enemies, one of the most serious being Oryctes rhinoceros, a large dynastine scarab beetle. Originating in South Asia, it has spread across the Pacific with the accidental assitance of man. It was first recorded from Upolu, Samoa in 1909, spread to Tonga in 1921, and was discovered on Wallis Island in 1931. World War II was instrumental to the spread of the insect to Papua New Guinea, and Fiji was invaded in 1953. Larvae grow well in a variety of organic matter including decaying vegetation, sawdust and cattle dung. The adult insects causes damage to the leaves, particularly new, actively growing axils. This damage weakens the plants and causes a loss in productivity.

Several methods have been investigated for their utility to control O. rhinoceros. Among these are the use of pathogenic fungi, and and pheromones. One of the most effective however, involves the use of a virus to infect and kill the insects. In 1963, larvae infected with a virus were discovered in Malaysia. Further investigation showed that this virus was effective for control of the beetle, and was able to be cultured in the laboratory. In 1964, the virus was released experimentally in Samoa. The virus spread quicker than expected and caused a major decline in the population of O. rhinoceros. The virus was then introduced to other countries, which also experienced the same decline. Unfortunately, it appears that the virulence of the virus has decreased. Populations are starting to increase, which is sparking further research into the virus and other control methods of the beetle.

C.C. Okaraonye and J.C. Ikewuchi have got an idea for a different biological control agent - humans. The larvae of O. rhinoceros are apparently highly nutritious and full of protein. They don't give any recipes unfortunately, but do say that they can be eaten raw, boiled, smoked or fried...

References:
Bedford, GO. (1976.)
Observations on the biology and ecology of Oryctes rhinoceros and Scapanes australis: pests of coconut palms in Melanesia.
Journal of the Australian Entomological Society 15:241-251

Bedford, GO. (1980.)
Biology, ecology, and control of palm rhinoceros beetles.
Annual Review of Entomology 25:309-339

Huger, AM (2005.)
The Oryctes virus: Its detection, identification, and implementation in biological control of the coconut palm rhinoceros beetle, Oryctes rhinoceros (Coleoptera: Scarabaeidae)
Journal of Invertebrate Pathology 89(1):78-84

Jackson TA, Crawford AM, Glare, TR. (2005.)
Oryctes virus—Time for a new look at a useful biocontrol agent
Journal of Invertebrate Pathology 89(1): 91-94

Okaraonye CC, Ikewuchi JC (2009.)
Nutritional potential of Oryctes rhinoceros larva
Pakistan Journal of Nutrition 8(1): 35-38

Photo courtesy of Huger (2005)

Belligerent newcomers and shrinking wings - Carabid Ecology on Maui

To make use of an allusion from literature, things are rotten in the Hawaiian Islands. Like many places, they are being overrun by Argentine ant (Linepithema humile) (Hymenoptera: Formicidae). Coupled with this, they also have a carabid beetle, Trechus obtusus that is running amok over the island of Maui. Stuck in the middle are a number of endemic carabids in the genus Mecyclothorax.

James Liebherr and Paul Krushelnycky have published a paper detailing the plight of the Mecyclothorax over the past seven years, and it makes for interesting reading. In a nutshell: Trechus obtusus was first found on the island of Maui in 1999 (sounds familiar…) and increased dramatically, such that a 4m2 collection of leaf litter in 2001 had 77 beetles in it. The numbers of Mecyclothorax since that time have had a statistically significant decline since then, while T. obtusus numbers remain approximately the same. The presence of ants is also an important predictor in whether or not Mecyclothorax is present in an area or not. The numbers of Mecyclothorax are significantly lower in ant-infested areas, while the abundance T. obtusus is not significantly affected by Argentine ants. It looks grim for Mecyclothorax, but the authors do not seem to express any pessimism about the future of the beetles.

Another interesting aspect about the system is how Trechus obtusus is losing its wings. T. obtusus has two forms - a fully winged (macropterous) form that can fly around, and a short winged (brachypterous) form whose wings reach halfway down the abdomen and is flightless. There has been a very rapid change in the proportion of wing forms in populations of T. obtusus on Maui. In one site, 0% of beetles collected in 2001 had short wings. Four years later, in 2005 15% of beetles collected were brachypterous. At another site the proportions have increased from 0% brachyptery to 18% in three years. This change has a number of possible consequences. It is hoped that the decrease in numbers of flighted individuals will help prevent T. obtusus from spreading to other Hawaiian Islands. However, this does not prevent it from invading through human transportation, which is the most likely way it got to Maui in the first place. Second, the dimorphism of T. obtusus will no doubt help it spread around Maui to a much greater extent, and form more stable populations, than the endemic Mecyclothorax which are exclusively brachypterous.


Wing dimorphism is considered to be determined by a single allele. Individuals with full wings are thought to be homozygous recessive, while shorter wings can be heterozygous or homozygous dominant. While the authors suggest that all of the first beetles to arrive were macropterous (i.e. homozygous recessive), this would seem to indicate that there would be no alleles for brachyptery in the population. The situation here probably suggests that wing size in carabids is slightly more complicated than classical Mendelian genetics, and that more than one allele influences the size of wings in Trechus obtusus.

The influence of Argentine ant on the populations of carabid beetles is also pretty scary. Argentine ant is one of the world's worst invasive ant species and it is established in Hawaii, New Zealand and Australia. It is not found elsewhere in the Pacific. It is one of the species on the Pacific Ant Prevention Plan and it is hoped that it doesn't get established. The carabids elsewhere in the Pacific are not well known, and their response to Argentine ant invasion would probably be similar to the situation in Hawaii.


The globalisation of biodiversity has had a huge impact on native ecosystems. It looks set to continue, despite advances in biosecurity policy and techniques. It looks gloomy, and to an extent it is. However, nature has survived this long, and will continue to get by, though in a slightly more impoverished state. Another aspect of invasions that I haven't looked up yet is the beneficial side, where new organisms enrich and add to the indigenous ecosystem. Does it happen? I don't know, and it's not something you hear about. Maybe an idea for someone?

Liebherr, JK; Krushelnycky PD. 2007.
Unfortunate encounters? Novel interactions of native Mecyclothorax, alien Trechus obtusus (Coleoptera: Carabidae), and Argentine ant (Linepithema humile, Hymenoptera: Formicidae) acress a Hawaiian landscape.
Journal of Insect Conservation 11:61-73

French Polynesia and the invasion of the Cicadellids...

1999 was a bad year for French Polynesian plants. In that year two species of highly generalist leafhoppers (Homoptera: Cidadellidae) were found on Tahiti. These were the catchy-named but highly harmful glassy-winged sharpshooter (Homalodisca vitripennis) and the two-spotted leafhopper (Sophonia orientalis). Since then the two have spread around French Polynesia, and are now in the Austral Islands and the Marquesas. In doing so, they have sparked a frenzy of research into their biology which has revealed a number of taxonomic difficulties. The story provides insight into the importance of good taxonomy, and its usefulness in real life.

The glassy-winged sharpshooter aptly got a lot of attention from its bold invasion. The insect is a hugely important vector for a number of plant diseases, is large, and is easily transported. It also excretes a lot of watery fluid, weakening plants and causing a nuisance for humans. As an added twist, it poisons predators that try to eat it. Since then it has been the subject of a biocontrol programme with the wasp Gonatocerus ashmeadi (Hymenoptera: Mymaridae).

While this was happening, the two-spotted leafhopper was slipping under the radar. My attention was brought to it when reading a paper by Aguin-Pombo, Aguiar and Kuznetsova in the Annals of the Entomological Society of America. The insect has made a hop over to the eastern Atlantic island of Madeira, where it was discovered in 2000. In their paper, Aguin-Pombo et al summarise what is known about the leafhopper, which has made itself a nuisance in Hawaii, California and now Madeira. They also provide a redescription of the insect, and comment on its taxonomy.

It turns out that there is a lot of confusion in the literature regarding the correct name and identity of the leafhopper. In this paper, the authors follow the rather convoluted path to the leafhopper's currently accepted name of Sophonia orientalis. Unfortunately though, there remains some confusion, in that the name given in most of the biological literature is S. rufofascia, currently a synonym of S. orientalis. The confusion seems to have arisen through a combined effect of scattered taxonomic literature, poor and incomplete descriptions, differing taxonomic opinion, and the inability to access type specimens. This is unfortunate, particularly in the situation of biological invasions, where it is necessary to quickly and confidently identify the species in question in order to evaluate the possible impact and to put managment strategies in place.

The taxonomic confusion hasn't been all one way though. I see that the glassy-winged sharpshooter has also had a recent name change from Homalodisca coagulata to H. vitripennis. The paper by Takiya, McKamey and Cavichiolil informing of the change is a paper of fine taxonomic detective work, and a good explanation of the rationale behind the change.

The Aguin-Pombo et al paper is also a good example of how taxonomic literature can be incorporated with other information to produce a much more useful document than a description of a single species. This has been the subject of discussion amongst some of my colleagues recently, and it is good to have a recent example. As well as the description, the paper by Aguin-Pombo et al incorporates karyological results (chromosome stuff) and information on the host plants, abundance, and establishment of the two-spotted leafhopper on Madeira.

It is unfortunate that these species invasions occurred at the same time, as resources which could have been used to control the two-spotted leafhopper were used to combat the sharpshooter. While the sharpshooter is an important pest, the leafhopper is not negligible either. In Hawaii and Madeira, it has been found to be malevolent towards banana, taro, sweet potato, papaya and mango - all of which are important food plants in the South Pacific.

The whole scenario is a good case study of the practical importance of taxonomy, and the necessity of good taxonomic work in the first place. It's a timely lesson for those of us entering the field, which we'd do well to heed.

Aguin-Pombo A, Aguiar AMF, Kuznetsova VG. 2007
Bionomics and taxonomy of leafhopper Sophonia orientalis (Homoptera:Cicadellidae), a Pacific pest species in the Macaronesian archipelagos.
Annals of the Entomological Society of America 100(1): 19-26