This latest beetle blog comes from two members of the Coleoptera section who are presently conducting fieldwork in China - Chris Lyal (researcher) and Conrad Gillett (PhD student). Chris and Conrad are collecting weevils (superfamily Curculionoidea) together with their Chinese colleague, Ren Li, from the Chinese Academy of Sciences.
Chris (left) and Conrad (right) in standard issue tropical weevil collecting uniform with their preferred weapons
Tropical montane forest in Xishuangbanna prefecture, Yunnan
"Weevils are the single most diverse family-level group of organisms on the planet, with an estimated 62,000 described species, or about 15% of all beetles. They are plant feeders with a wide variety of life histories, ecologies and interesting distribution patterns, often linked to the distribution of their host plants, which can be very specific (often a single plant species) or more general. Weevils are therefore worthy of study not only because of their intrinsic interest in being highly diverse, but also because we can investigate their co-evolution with plants and the many and varied adaptations that they have developed for feeding on these and on different plant tissues such as leaves, bark, wood, roots and seeds. They are also important because a number of species are now widespread pests of plants cultivated by man, such as palms and bananas, or even the vectors responsible for transmitting fungal diseases such as Dutch elm disease. However, on the positive side, weevils have also been used as biological controls against invasive plants that have been spread by man outside of their natural ranges."
Weevils are generally recognised at first glance by possessing an extension of the head called the ‘rostrum’, at the end of which the biting mouthparts are located. The rostrum has the appearance of a ‘proboscis’ though it is nothing like that of a butterfly’s. At the moment there is a great deal of uncertainty as to how the various subgroups within the weevils are related to one another. Conrad is currently tackling this problem through analysing their genetic information, the DNA in a number of different genes, from a wide range of weevils belonging to as many of the weevil subfamilies and tribes (both these are taxonomic groups below the family level) as possible.
Leaf-rolling weevil (Attelabidae)
"There are around 300 currently accepted weevil tribes – think of these as lineages – and we need to sample as many of these as possible to get a clearer picture of how they are related. We need to collect specimens that are fresh because otherwise it is difficult or impossible to obtain DNA for analysis. The specimens are collected into pure ethanol, which preserves their DNA, until we can bring them back to the laboratory where the genetic work is done. We have come to southern China’s Yunnan province because it is a very interesting area, known as a ‘biogeographic crossroad’, which means that here two biogeographic regions, the eastern Palaearctic (northern Asia) and the Oriental (southeast Asia) meet, and elements from both their faunas can be found in one area. Each biogeographic region usually contains species that are only found there, but where two regions adjoin each other, it is possible to find species from both together or very close by – this is why biogeographic crossroads are so biodiverse; they also usually contain a wide variety of habitats, which can be separated by elevation or by localised microclimates.
Weevils occur in all terrestrial habitats where plants are found, so we need to look in as many of these as possible, such as in rainforests and montane forests. Before coming out here we had not been able to get specimens from a number of tribes that occur in these two biogeographic regions, so it is really important to try to find them for our investigation."
Chris and Conrad have spent the last week collecting at several sites in the Xishuangbanna prefecture in the south of Yunnan. This is an area of relatively low elevation (at least for Yunnan, which has mountains towering to heights of 6000m in the north!) and of tropical and subtropical climate. The tropic of Cancer crosses the area, which also borders Myanmar and Laos to the south. So how are they managing to find these weevils?
Weevil (Molytinae) and weevil hunter (Homidae)
"Because weevils live on plants, in order to collect them we look for them on as many different species of plants and parts of plants that we can. To do this we beat vegetation and foliage onto a sheet which allows us to see the weevils that are knocked off the plants and to collect them into tubes or into a ‘pooter’ (if anybody is interested we’ll explain that rather curious item of equipment in another blog – just think of it as a mouth-operated vacuum cleaner). We also use a ‘sweep-net’ to sweep across low vegetation for weevils and we look closely at fallen or cut tree trunks, logs and branches, as well as looking under bark. Of course it is not only weevils that we see, in fact we have come across representatives of many insect orders during the course of our collecting.
Large longhorn beetle (Batocera sp., Lamiinae) found stuck in its too-tight pupal chamber in a fallen tree – and ‘rescued’ (with the help of a swiss army knife), albeit in three pieces!
These have included many bugs, ants, wasps, and an incredible variety of praying mantids and spiders as well as the odd stick insect, and other beetles, especially leaf beetles (Chrysomelidae) and ladybirds (Coccinelidae) to name just a few. The diversity of butterflies has also been quite good, with the large and gaily coloured swallowtails being particularly delightful. Beating and sweeping will also pick up the odd vertebrate including lizards and frogs which are only to glad to be able to beat a hasty retreat once released!
A lizard we accidently caught out of a bush was kind enough to pose for us before making good its escape
A jade-coloured swallowtail (Papillionidae) in all its glory – perhaps a reader will know which species!
In addition to these active forms of collecting, we have also set up some traps, including combined malaise and flight-interception traps (to catch flying weevils) and banana-baited bottle traps placed in trees to hopefully catch some species that are attracted to the bait. We’ll be checking the traps in a couple of days, so hopefully we’ll report back on the results in our next blog entry."
Malaise trap in operation
One of many species of praying mantis we have seen in Yunnan
Climatic conditions can have a major impact on how easy it is to collect beetles and the time of year for the expedition was chosen carefully to coincide with the start of the rainy season to increase the chances of success (many insects emerge or are more abundant during this period). Travelling to a new area for our scientists is also challenging because one can never quite know exactly what it will be like and what trials and tribulations may lurk ahead! How has this been affecting collecting?
"China is an enormous country and when we arrived here we spent a day at the Chinese Academy of Sciences in Beijing, in the northeast of the country, which was still very much in the grip of winter, with no sign of leaves on the trees yet. But when we first arrived in Kunming (the capital city of Yunnan) things could not have been more different, and the tropical luxuriant vegetation was in stark contrast to what we had left behind in Beijing a few hours earlier. It was also a lot warmer and more humid of course! However our first few days of collecting in the forested hills in the vicinity of the town of Pu’er showed us that in fact it was still quite dry and the rainy season had not yet begun there. Consequently finding weevils was quite difficult as their activity was low. It has also not been particularly easy to find completely wild and untouched natural areas because a lot of the Chinese countryside and landscape is intensively used, either for agriculture or for housing, and evidence of new large-scale development is evident almost everywhere we have been.
Three of the surviving elephants in the area
However, we decided to move further south and we are presently in the area around Menglunzhen which has received its first few rainstorms and consequently we are finding more and more weevils each day. There is an air of things being ‘on the cusp’ of exploding into full activity, which was evident last night when there was a greatly increased activity of insects attracted to the lights in the Xishuangbanna tropical botanical garden, which is where we are based at the moment!
Sunset over Xishuangbanna tropical botanical gardens
So far, although it is difficult to identify weevils in the field without the use of a microscope and all the relevant taxonomic literature, we think that we have found several very interesting specimens for the study. Some of the highlights have included a finding a good range of molytine weevils (this subfamily is one that Chris is especially interested in), and Conrad has particularly enjoyed trying to catch the quick-moving and flighty conoderine weevils found on dead wood – equally as challenging as hunting agile tiger beetles or jewel beetles!
A lurid pink molytine weevil (Molytinae)
A fast-moving and very nervous conoderine weevil (Conoderinae) on a dead branch– they are challenging to collect and difficult to photograph!
We are also hoping to find new species of weevil to describe together with our Chinese partners, and this co-operation between our institutes is something we are both keen to promote and to foster."
China has of course a rich cultural heritage and an ancient civilisation, so what have our colleagues experienced of this? And how are they getting by with the language?
"We have been very fortunate in that our Chinese colleague Ren Li, who has come out with us, is helping us out with all the day-to day things which would be very difficult without speaking Chinese (which neither of us do!). It has been very interesting just seeing how people go about their lives here, although I think even to our Chinese friend, things down here in the tropical south are quite different to back in Beijing! We have seen some interesting sites including an abandoned and overgrown but still grandiose complex of temples and festive sites where we collected and the beautiful botanic gardens mentioned earlier.
Chinese dragons guarding over an abandoned temple
We have also been lucky because we are experiencing some authentic Chinese cuisine as we are well off the tourist trail and Ren Li is ensuring that we taste the local specialities. Thus far we have had epicurean delights including (but not limited to) duck tongue, marine snails and the famous thousand year old eggs!
After a day’s collecting, an evening meal with our Chinese colleague Ren Li (left) in Menglunzhen
We have also been impressed by the popular local transport, an intriguing combination of pick-up truck and motorbike – who wouldn’t want one? We haven’t been so impressed with the laundry service at a hotel we stayed at, with some of our undies going AWOL!
Who wouldn’t want one of these?
Weevil keep you informed with our progress!
Conrad and Chris, 13 April 2012, Xishuangbanna prefecture