THE WON­DER­FUL WASP

Wasps de­serve re­spect not a swat­ter, says Seirian Sum­ner – who re­veals their fas­ci­nat­ing so­ci­eties and hugely ben­e­fi­cial pres­ence in our gar­dens and wider coun­try­side.

Countryfile Magazine - - Contents -

Con­sider the sounds of high sum­mer: the chat­ter­ing of rooftop star­lings, the hum of your neigh­bour’s lawn­mower. Lis­ten more closely and you might be hear the del­i­cate scratch­ing of a wasp on the wood of your gar­den shed.

Far from be­ing a ma­li­cious pest look­ing to ruin your pic­nic, this lady (they’re all fe­males at this time of year) is com­pletely fo­cused on col­lect­ing wood pulp to ex­pand her mother’s nest. It’s a labour of ge­netic love – the harder she works, the more wasps her mother’s nest will pro­duce, and the more of her genes will be passed on to the next gen­er­a­tion.

The wasp in ques­tion is the yel­low­jacket (Ve­spula vul­garis), the black and stripy species you of­ten find your­self swat­ting away. The rep­u­ta­tion of this and a few other species has tarred that of an­other 200,000. In­deed, wasps are sec­ond only to bee­tles in terms of species num­bers and there are thought to be at least 100,000 more wait­ing to be dis­cov­ered. So­cial wasps (that in­cludes our stripy friend) rep­re­sent less than one per cent of the to­tal wasp species in the world. And most aren’t yel­low and stripy or fond of pic­nics. The vast ma­jor­ity of de­scribed wasps are tiny black in­sects that you’d prob­a­bly mis­take for flies. In fact, the small­est in­sect in the world is a wasp: the ‘fairyfly’ is a mere 0.14mm long and only lives for a few days. De­spite its size, it plays a vi­tal role in agri­cul­ture, as it lays its eggs in the bod­ies of crop pests, es­sen­tially work­ing as an al­ter­na­tive to chem­i­cal pes­ti­cides.

PEST CON­TROLLERS

There are many rea­sons to love (or at least ap­pre­ci­ate) wasps, the main one be­ing that they help keep in­sect, spi­der and woodlice pop­u­la­tions at bay. As preda­tors, they’re at the top of the food chain and without them food webs would break down. They’re also gen­er­al­ists: wasps will feed on what­ever’s around. They eat the most abun­dant pests that we try to con­trol with toxic chem­i­cals – there’d be many more aphids in my gar­den without wasps. We don’t have good data on how much wasps eat, but a sin­gle colony is thought to re­move some­where

be­tween 0.16-23kg of prey per sea­son. Us­ing a mod­est es­ti­mate, that amounts to about 250,000 aphids from each colony.

Wasps are also pol­li­na­tors of flow­ers and crops. Adult wasps don’t need much pro­tein (the bugs they prey on are for the de­vel­op­ing brood in the nest) but they do need sugar, which they get in the form of nec­tar from flow­ers. In the process of find­ing it, the wasps pick up and trans­fer pollen from flower to flower. Un­like many bees, wasps don’t mind what flow­ers they visit – as gen­er­al­ist pol­li­na­tors they’re more abun­dant than bees in de­graded or frag­mented habi­tats and so are im­por­tant ‘back-up’ pol­li­na­tors in these ar­eas.

Wasps also have a fas­ci­nat­ing so­cial life. A yel­low­jacket colony is much like that of a hon­ey­bee, with a queen sup­ported by a com­mu­nity of work­ers. It sounds har­mo­nious but look closer and you’ll see a ver­i­ta­ble Game of Thrones in full swing. The par­al­lels with hu­man so­ci­eties are un­canny: there are spe­cial­ist work forces, re­bel­lions, polic­ing, lead­er­ship con­tests, un­der­tak­ers, po­lice, even free-load­ers and anti-so­cial thugs. You name it, so­cial wasps have it.

CON­TIN­GENT LOY­ALTY

The lives of so­cial wasps re­volve around gene-shar­ing (or re­lat­ed­ness). Worker wasps are ‘self-sac­ri­fi­cers’, they have evolved to work rather than re­pro­duce be­cause their genes are passed on through the brood they help rear (their sib­lings).

But this so­cial con­tract is only a good deal if their mother is singly mated. Queen wasps only have one mat­ing flight in their lives, but dur­ing that time some species mate with sev­eral males: they store the sperm in their ab­domen and con­trol its re­lease to fer­tilise the eggs they lay through­out their lives.

Mul­ti­ple mat­ing means the queen di­lutes the re­lat­ed­ness of the work­ers in her brood and work­ers end up rear­ing a mix of half- and full-sib­lings, which can break the so­cial con­tract of the colony. In these cases, work­ers can do bet­ter, in­di­vid­u­ally, if they lay their own eggs. And this is when things get messy: sneaky egg lay­ing by work­ers can cause a colony’s co­he­sion to break down, cre­at­ing in­ter­nal bat­tles among the work­ers. They may be blood­less bat­tles, as no in­sect blood (haemolymph) is shed, but they’re fought by ruth­less means: work­ers that de­tect an­other worker’s eggs will eat them be­fore they hatch.

But aren’t we taught in schools that only queens lay eggs? In fact, work­ers

“PER­HAPS WE HAVE WASPS TO THANK FOR MUCH OF OUR RICH CUL­TURAL HIS­TORY”

in al­most all Hy­menoptera (bee, wasp and ant) colonies can lay eggs. Be­cause of a ge­netic quirk of the Hy­menoptera, fe­males hatch from fer­tilised eggs and males from un­fer­tilised eggs. Worker wasps have lost the abil­ity to mate, but can still lay male (un­fer­tilised) eggs.

GOOD FOR BODY AND MIND

There are other rea­sons to ad­mire wasps. For one thing, they may be in­di­rectly re­spon­si­ble for the in­ven­tion of pa­per. Around 2,000 years ago a Chi­nese eunuch called Cai Lun no­ticed a wasp build­ing a pa­per nest in his gar­den. In­spired by what he saw, he started to mulch wood and with it made the first pa­per. If the story is true, then per­haps we have wasps to thank for much of our rich cul­tural his­tory and de­vel­op­ment.

Fast for­ward to to­day where ex­cit­ing re­search is look­ing into the po­ten­tial use of wasp venom as a can­cer ther­apy. An ac­tive pep­tide found in the venom of trop­i­cal so­cial wasps se­lec­tively de­stroys can­cer­ous cells by caus­ing their mem­branes to leak. Wasps may have the po­ten­tial to save hu­man lives.

A bet­ter ap­pre­ci­a­tion of the eco­log­i­cal, eco­nomic, med­i­cal and cul­tural ser­vices that our stripy friends pro­vide might help us see them in a dif­fer­ent light. So next time your pic­nic is dis­turbed by black and yel­low in­sects, take a mo­ment to think about their ex­tra­or­di­nary world and the con­tri­bu­tions they make to our lives be­fore you reach for the swat­ter.

WASP SUR­VEY You can take part in the 2018 sur­vey by putting out a wasp trap be­tween 25 Au­gust and the 1st Septem­ber. Find full de­tails of the sur­vey at www.big­wasp­sur­vey.org

Dr Seirian Sum­ner is a be­havioural ecol­o­gist at Univer­sity Col­lege Lon­don. Her re­search fo­cuses on un­der­stand­ing how and why an­i­mals and in­sects such as wasps live in so­ci­eties.

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