The scent of the Waggle Dance.

Exams are upon us so I thought I would combine the last ENTO blog with learning for 2 exams!

The honey bee (Apis mellifera) covers aspects of ENTO 304, learning for flight & wings on 2^nd & 3^rd thoracic segments (more correctly called mesathoracic & metathoracic segments) with hammuli (hooks on hind wings which enable both fore and hind wings to couple together for flight to act as one wing), adaptations on hind legs (enlarged first tarsomere with combs) for holding pollen and packing into ’baskets’ and modified abdominal appendages called ovipositors forming the stinger. Also the honey bee is an ideal example for ECOL 311, covering sociality and optimal foraging theory not to mention pollination. But that’s another story. I’m going to cover some of the social insect side and the waggle dance.

Bees are a social insect and survival of the hive is dependent on the majority surviving.  The pressure is on individual bees to find food with the least amount of energy expended and take it back to the hive to feed the holomeatabolous larvae (complete metamorphosis that the juvenile form does not resemble the adult).The cost may be their own life ending. It is therefore beneficial to tell foraging bees where a food supply is (Alcock 2001). Foraging bees are the female workers aged from 22 days and older. Each bee in a hive has a different job to do determined by age. The hive can only work if each individual is working for the benefit of the hive. 

This paper is on the waggle dance of the honey bee (Thom 2007). It is a form of communication and behaviour in social insects to let the other members of the hive, the workers or foragers locate a newly found supply of food. This is a dance done darkness of the hive on the honeycomb and is followed by other foragers. Here they rely on pheromones (chemical odours) and vibrations, felt by antennae, to detect the movement. Communal recognition through pheromones are important in the darkness for nest mate recognition as well as food source. Two important pheromones have been detected in foraging bees which go in depth in the paper so will not mention any more here. If it is performed outside it is on a horizontal surface (Alcock 2001). It effectively gives them directions to the flowers. The pattern is a sort of number 8 figure with a wiggle in the centre (fig.1).

Figure 1; the pattern of the dance in relation to the sun’s angle.

Now to understand how bees can tell from this dance where food is.

If the bee goes in a circle then the flowers are close.  If the dance has a waggle further away than 50 m. By measuring the number of circuits completed or the duration of the waggle we can work out the distance from the hive. The longer the waggle dances the further from the hive is the food source. By measuring the angle of the waggle with the vertical, the direction of the food is given (fig. 1). A bee on its way home can note the angle between the flowers, sun and hive. A fun to watch clip of the Waggle dance of honey bees is on you tube; hyperlink;

 http://www.youtube.com/watch?v=-7ijI-g4jHg. 

You may tell from just this short extract how complicated the honey bee has become. What an amazing little insect, one we don't want to loose.

References

Alcock J 2001.Animal Behaviour, chp 8, 7^th ed; Sinauer Associates, Inc. Massachusettes

Thom C, Gilley DC, Hooper J, Esch HE 2007. The scent of the Waggle Dance. PloS Biology, 5(9); e228.

Red Imported Fire Ant ( RIFA)

Red Imported Fire Ant (Solenopsis invicta Buren) Hymenoptera: Formicidae.

 A Red Imported Fire Ants, RIFA, colony can contain hundreds to thousands of polymorphic (different sizes) workers. The nest appears as a mound of dirt usually within an open area having a crust to help weatherproof the nest. The average size is 10-24 inches in diameter and 6-18 inches in height. These ants can have one reproductive queen (monogyne) or have multiple reproductive queens (polygyne) in a nest. These two social forms can exist and they differ in mode of dispersal and density of nests. They are reddy-brown in appearance on the head and thorax but the abdomen is black. It has a ‘super model waist’ correctly called a petiole.

 Identifying characteristics on the fire ant workerhead: ten-segmented antennae with two-

The RIFA is an important invasive species which could potentially be damaging to NZ economy and to human health. RIFA  have a toxic sting and there have been deaths associated with repeated stings. They eat almost anything including animal, dead or alive, can damage crops and machinery. They are very protective and aggressive of the nest area. There have been three incursions (new entry into an area by an unwanted species) in 2001, 2004 & 2006 in New Zealand by MAF (Ministry of Agriculture & Fisheries) Biosecurity. In 2001, a single nest was found at Auckland airport. In 2004 a second nest was found at Port Napier in Napier and in 2006 a third nest was reported at Whirinaki, near Napier in a forestry block. Samples were taken of worker ants for identification.



Multiple ant stings



Molecular analysis using mitochondrial DNA (mtDNA) instead of nuclear DNA can determine close relatives and the likely source of the incursion. If it is known where they come from additional measures can be put in place to prevent further incursions.  Using alleles, fragments of DNA or more simply put genetic material, from mtDNA can also determine likely country of origin. The gene, GP-9, has 2 main alleles B and b; the monogyne form having BB and the polygyne being Bb. Interesting to note that forms of bb die. Results from testing these incursions showed that 2006 was from a polygyne colony while the 2004 was from a monogyne. The DNA from 2001 was too old to retrieve a sample. Results show there is no single entry point into NZ.

New Zealand has cooler temperatures that make it more difficult for them to survive here limiting incursions to the warmer parts of the North Island. Incursions and spread tends to be accidental by human transport. However the nest found in 2006 is suspected to have been present at least two years and not related to the 2004 incursion. Social forms determine management strategies. Polygyne nests tend to be larger but fertile queens may leave once winged and travel short distances from the parent nest. They also may be monogyne. It has been theorised that the larger nests may be able to cope with NZ winters as they can generate a higher stable internal temperature.

References

Corin, S. E., Ritchie, P. A. & Lester, P.J. (2008). Introduction pathway analysis into New Zealand highlights a source population ‘Hotspot” in the native range of the Red Imported Fire Ant (Solenopsis invicta). Sociobiology, 52; 129-143.

Miller, D. & Allen, H. (2010), Red Imported Fire Ant (RIFA),Publication 444-284,Virginia State University; http://pubs.ext.vt.edu/444/444-284/444-284.html



 

Scale insects

Sooty beech scale insect (Ultracoelostoma spp.)

On a visit to Ashley Gorge, Oxford, New Zealand,we were having a quiet relaxing bush walk through  the native forest but by the time we got back to the car we were covered in sooty mould, especially my 10 year old son!!.

 

 Figure 1: Beech trees (Nothofagus spp.) at the lookout at Ashley Gorge, New Zealand.

My sons had asked all sorts of questions regarding the black mess covering the trees, some of which I could answer and others not. This I decided would be a good subject for a blog.

The sooty mould fungus (Capnodium spp) lives off the honeydew produced by the sooty beech scale insect (Ultracoelostoma assimile (Maskell) and Ultracoelostoma brittini). There are 11 families in New Zealand, most are host specific. The sooty beech scale (Ultracoelostoma spp.) is in the order Hemiptera. There appears to be confusion over which family they belong; in Duncan et al. (2007) it is in the Coelostomiddiidae family and in Wardhaugh & Didham (2006), it is the Margarodidae family. Perhaps someone can clarify this for me? Scientific names aside it turns out to be a fascinating insect. How many insects do you know that spend the majority of its time with its head stuck in a tree and its rear end protruding out (I’m trying to be polite) with a long tube secreting honeydew, the waste product or poo)(fig.3)?

Figure 2; the beech in the background is black from sooty mould compared to the foreground understory, Ashley Gorge.

There are three distinct types; armoured scales, mealy bugs and soft scales. The soft scales’ are the sooty beech scale and tend to be found at the trunk and lower branches regions of the tree living between the bark crevices. They are a sap sucking insect, feeding on phloem (sap) of the tree.   

Figure 3; Sooty beech scale insects on a beech tree showing the filamentous anal tube protruding , the white thread  hanging down from the bark. Glistening in the light at the ends of the threads’ was a drop of honeydew (arrow at the top of picture).NB. I can't get the arrow to show but top right of the picture.

Lifecycle

Life history (fig.4).

 Each stage of development of the larval form is called an instar. After the egg has hatched, the first instar crawls out of the test to the outside. From this stage the larvae is called a crawler. The test is a hard waxy case developing over and encompassing the mother forming a barrier from the outside world.  Once the crawler is in place, a sticky substance released by glands under the epidermis layer forms the test. This hardens and additional layers are added with each moult. Scientists are able to determine the age by number of the number of casts against the test. However the anal tube or filament extends out beyond the case and is the only opening. The cast is the old skin that has been shed as the larvae out grows its skin and replaced with a bigger one.

The sooty beech scale female has 4 instars. However the last instar it still resembles the larva. This is known as an incomplete metamorphosis. The male has 5 instars and does complete a full metamorphosis taking on a different shape as an adult. The female also has a non terminal instar developing reproductive features of an adult. This is called Neoteny.

Female; the first instar is approximately 1 mm long. Once it has found a suitable crevice in the bark, it inserts its’ stylet and spends the rest of its life fixed to the tree. Once the stylet is attached, the anal tube elongates out of the tree as along filament. Waste products are passed out the tube well away from the body. The waste product is called honeydew and is sweet tasting (We did the taste test, yum) being high in sugars from undigested tree sap.

 The second instar has grown to approximately 1.6 mm in length. The outer test is hard and a reduction in leg length, antennae are shortened and the eyes are reduced. General shape is changing and becoming more spherical. The end cap has darkened and appears black close to the bark.

 The third instar stages, they are 2-4 mm diameter now, tight against the test. There is further reduction of legs, eyes & antennae. The anal area has become thickened with a raised ring around the anus.

 The fourth instar still resembles the larval stage. This is the adult stage but with non functional mouthparts and no legs and it no longer produces honeydew. Eggs are laid within the test then the female shrivels and dies. The crawlers leave through the anal hole.

Male; the male has the same first and second instar stages but remains active in the third. The fourth stage it pupates and is a winged adult at the fifth and final stage. The adult is approximately 3-4 mm and is a reddish pink colour. The male flies to the females in the trees to fertilise the eggs. It has no mouth parts and will live only to reproduce then die.

   

Figure 4; Life history of sooty beech scale (Morales et al 1988).

The sooty beech scale is a keystone species, i.e. without the scale insects the ecosystem disappears. Honeydew is an essential nectar source for insects including wasps, bees and ants, for native birds such as tui, and bellbirds and also for the sooty mould fungi.

An unexpected by product of the honeydew is exported honey by ‘Airborne’. This is exported to Europe and Germany as honeydew honey. The nectar has special qualities with the presence of oligiosaccharides (complex sugars), higher levels than are present in flowers. It has higher other sugars (maltose, erlose & melezitose) but lower in sugars (glucose & fructose) that cause honey to crystallize. It is high in polyphenolics (antioxidants) & high in Glucose oxidase (antibacterial properties). Another words medicinally healthy honey.

 What a good life a female sooty beech scale has. As much food as you can eat, warm environment with no frosts, snow or rain and what’s even better the male comes to you. Bliss.

I hope you enjoyed my ‘walk’ through the bush. My boys did. They can’t wait to tell all their friends at school they ate poo in the holidays!!

References & Links

Astwood, K., Lee, B. & Manley-Harris. M.,(1998). Oligosaccharides in New Zealand Honeydew Honey, Journal of Agricultural and  Food Chemistry, 46(12), 4958-4962.

Airborne honey web site (1999)..; http://www.airborne.co.nz/hnydew.shtml

Morales, C.F., Hill, M.G. & Walker, A.K. (1988). Life history of the sooty beech scale (Ultracoelostoma assimile) (Maskell), (Hemiptera: Margarodidae) in New Zealand Nothofagus forests. New Zealand Entomologist, 11; 24-37. http://www.ento.org.nz/nzentomologist/free_issues/NZEnto11_1_1988/Volume%2011-24-37.pdf.

Morales, C.F. (1991). Margarodidae (Insecta: Hemiptera). Fauna of New Zealand 21, 124 pages. http://www.landcareresearch.co.nz/research/biosystematics/invertebrates/faunaofnz/Extracts/FNZ21/fnz21pop.asp.

Wardhaugh, C.W. & Didham,  R.K. (2006). Establishment success of sooty beech scale insects, Ultracoelostoma spp., on different host tree species in New Zealand. Journal of insect Science, 6: (29) 1536-2442. http://www.insectscience.org/6.29/i1536-2442-2006-29.pdf.

Welcome

Hi

This blog has been started as part of a Bachelor of Science Degree at Lincoln University Christchurch, New Zealand.

I’m writing this blog for an Entomology assignment as part of teaching us communication of scientific ideas to interested people. Learning about entomology and communicating this to others as well as how to write a blog is going to be a steep learning curve but fun. This is my first attempt. 

 My topics will be on insects I want to learn about, starting this week with Scale insects. I welcome feed back or ideas of interesting insects to write and learn about.

Jenny