Thursday, October 9, 2014

I learned something new in a round-about way

I just learned something that I had missed so far because I was always too squeamish to observe it. The birth of a maggot that is. I remember being fascinated by a wiggling masses of white worms on a dead mouse that a hawk had dropped in our backyard - I was 4 and we had just moved from the city to the countryside. My mother was properly repulsed and worried about germs. I had also gotten a whiff of a smell that was more than unpleasant. So - no forensic interest was triggered in early childhood or even later when studying physiology and having to breed flies for their big eyes that were easy targets for beginning neurophydiologists' electrodes.

Entomologist collecting beetles from an old cow carcass
Nowadays I sometimes carefully look over the shoulder of an entomologists who sees animal cadavers as an interesting source for beetle specimens, but even then we tend to stay away from the most smelly rotting stages that flies prefer.


Stapelia gigantea
However, living in the desert, I love succulents, including Stapelia species from Africa. These plants use a very deceptive strategy to attract pollinators: instead of offering nectar or an abundance of pollen and the sweet fragrances that would announce those delicacies, Stapelias stink. They imitate very convincingly the odor of putrefaction, the odor of rotting meat. The one on our patio, Stapelia gigantea, the Giant Starfish Cadaver Flower, also looks like a piece of wrinkled, ripped skin with remnants of fur still on it.  All that of course to attract their pollinators. According to Wikipedia those would be mostly Blow Flies in the family Calliphoridae. Those green bottle flies would crawl around among anthers and stigma trying to find a good location to deposit their eggs on the presumed rotting meat and in the process pollinate the flowers.

Powerpoint file about deception directed at pollinators, examples Ophris and Stapelia
I sometimes give talks about pollination by insects other than honey bees, so when flowers of my  patio plant had opened up and some insects approached its center I was ready with my camera.
But at first, there were no green bottle flies.

Braconidae (Braconid Wasps), Alysiinae
 The first visitors I recognized as parasitic wasps. I had seen them before. Whenever I find a dead mouse in the garage or a bird that had hit a window pane these black and red wasps are around. They are associated with Sarcophagids, the big grey Flesh Flies whose larvae they use as hosts for their own offspring. 


2 wasps, and a Flesh Fly
Another smaller wasp and a big Sarcophaga sp. female arrived next. I knew that the fly was a female because her big compound eyes did not touch on top of her head as the male's eyes do (that much I do remember from my electrophysiology days). 

Sarcophage female giving birth to live maggots
 For me, the interesting part began here:
She crawled around in the center of the flower, probably doing the pollination duty that she was tricked into. Then she emitted bursts of sharp buzzing. At this time her abdomen was pointed pretty much at the center of the flower, the area that probably emits the foul smell. She seemed to be laying eggs, piling up a clump of little whitish cylinders.

video

The video function of my camera was running at this point, so I had a good close-up view on the screen. To my surprise, the cylinders moved and crawled deeper into the center of the flower. Not eggs. The fly was giving birth to live maggots. (Now I've learned that all members of the family Sarcophagidae are larviparous or ovoviviparous). Under normal circumstances, this would give the maggots a head-start over other consumers of the limited resource that they depend on. Little Burrowing Beetles for example have a slower start, being deposited in egg-form, but then they can rely on the tender loving care of both their parents, a luxury the flies have to do without.
But under normal circumstances, I never would have had my camera positioned so close to an egg-laying flesh fly. Recording it it on a flower instead of on rotting flesh made all the difference. 
These larvae, though, are condemned to starve to death in the heart of the flower because their mother fell fore the deception of a devious plant. With them, the offspring of the parasitic wasp (a Sarcophgid specialist) is also bound to die.


A Green Bottle Fly has also arrived (left)
 We often think of pollination as this beautiful system of symbiosis between plants and insects, with dutiful bees doing their part, being then so richly rewarded that they don't mind sharing with yet another symbiont, the bee keeper (or should we call him a parasite of the system?)
In reality, plants have evolved to propagate their genes. That's it. They may pay for pollination services with nectar, drugs (Datura and Manduca) sex (Bumblee Ophris and hymenoptera) or let little fly-babies starve to death. The plant does not care!


I thought I'd also add a photo of the 'normal' situation. Here a  carrion beetle, Thanatophilus truncatus, a blow fly,  Calliphoridae and again a parasitic wasp, Braconidae have found a dead deer calf. They were the first to arrive in the morning after the deer had been run over by a car at night. Their larvae will act as macro-decomposer, opening the way for bacteria and fungi. This is a very important role for insects in the ecological system.

Sunday, October 5, 2014

Hot Peppers


At the beginning of summer one of our big box stores was offering all kinds of little pepper plants for next to nothing. So we probably took home more than we will ever want to eat.
The plants grew very well in pots on the patio where they used to get morning sun and then shade from the roof as the sun rose to the zenith. Now that autumn is upon us Arizona still gets hot, but the sun rays come in at an angle that exposes the peppers to so many more hours of light and heat that actually have to water them twice a day.


With the help of our nitrogen rich compost and some doses of Epson Salt to replenish the soil's magnesium the plants are growing beautifully. While the Jalopenos are towering over my head by now, Tabasco and Cayenne have turned into more delicate and very ornamental plants, studded with colorful small fruits. My old volunteer bell pepper plants are also constantly producing small but tasty pods. We are very much enjoying a wall of healthy green leaves that we already shared with two generations of leaf-cutter bees.


No one else has attacked our pepper plants yet. That somewhat surprises me because they have close relatives in our ecosystem, the red, spicy, pee-sized chiltepins, so they should have natural consumers.  'Of course', the Tucson Backyard Gardeners say 'Their spiciness protects them'. With this in mind, the gardeners produce concoctions of hot pepper that they then spray on all kinds of plants to prevent all kinds of  'pests'.
It sometimes works, probably because they usually add more than one ingredient to their 'organic pesticide' so it's never clear which component is actually effective. Or the pest was the household dog, and dogs do not like pepper spray  in their sensitive noses. But......


The ingredient that makes peppers hot and spicy and in high concentrations irritating to mucous membranes is called Capsaicin. It is present throughout the fruit and most concentrated in the placental membranes where the seeds are attached.
Capsaicin is known to stimulate temperature and pain receptors in mammals (like rodents, dogs, humans and bears). 
When I was working at my Ph. D. at the Max Planck Institute in Bad Nauheim, Germany, a friend of mine, Herbert Schmidt, tested the effect of capsaicin on  birds (he is an electro-physiologist and worked on tissue samples). He could show that while mammalian thermo and pain receptors both responded to capsaicin applications  (some of its therapeutic value is based on that effect), a similar response to capsaicin was not found in bird tissue.

When I came to Arizona, the folks at Native seed Search offered a plausible explanation: The red, attractive fruit of chiltepins, tabasco, jalopeno et all are probably exposed to several kinds of 'harvesters': Small mammals like packrats and mice, big mammals like javelinas, bears and humans, and birds.
Plants produce fruit to disperse their seeds. Many are juicy and inviting to attract animals to do the job, carry the fruit away, eat the juicy flesh but hopefully leave the seeds unharmed.  But if  rodents would feast on peppers, they would probably eat the juicy flesh and also chew up the seeds. This would destroy them and make them useless for plant propagation. So pepper plants evolved to load the fruit with capsaicin to make them rather impalatable to rats, squirrels et al.


But that's not good enough. The seeds are not supposed to just drop down under the mother plant to germinate in its shade and let the seedlings compete with each other. To thrive, they need to be dispersed.  So the inviting fleshy fruit is not a forbidden one to every harvester:  Birds suffer no ill effects at all because their receptors do not react to capsaicin. So they are free to eat the peppers. Not having teeth, they swallow the seeds whole and pass them through their digestive system, planting new pepper plants in their wake.
Perhaps even big mammals who don't bother to crack open every small seed would eventually excrete them in a viable state. The capsaicin response is dose related, meaning that a big bear or human may enjoy a delicate tickle where a small rat would suffer very serious heartburn. So maybe?

Anyway, the bright red, inviting, spicy peppers that signals 'stop' to rodents and other small mammals, can be an invitation to others.
(Sweet bell peppers are the result of selective breeding and do not occur in the wild)

I knew those research results and theories, but until today, the practical experience was missing. Sure, our packrats are leaving the peppers alone, so are our dogs, and we humans love them in small amounts. But the birds???


By the beginning of October, the candle-like upright Tabasco Peppers finally ripen, softening and turning from pale white to orange. (Wind and dogs have been playing with the labels that I was keeping with the pots, so there may have been mix-ups, but it's either serrano, tabasco or cayenne.) Yesterday I noticed that several fruits were shredded open on one side.  


Today during breakfast we finally cought the 'culprit'in the act.  Chattering happily a Verdin was intensely at work in in the Tabasco plant. Catching insects? Snacking on nectar from the few remaining flowers? No. He was going for the fruit. He devoured the fruit flesh and happily pecked at the seeds. Half a day later, most of the orange fruit were more or less gone, seeds and all.


 I am happy to have finally witnessed the story in real life and I am also glad that just a day earlier I had the bright idea to finally pick a bunch of peppers and pickle them in sweet vinegar.  
 
   

Friday, October 3, 2014

Toxic Shocker?


The BBC  recently acquired one of my spider photos for the October issue of their Wildlife magazine. The blurb with it was 'shockingly' racy and hyped up in true mass media fashion.




But the source link under the article lead to a publication of solid electrophysiology in Nature Communications:

Niraj S. Bende, Sławomir Dziemborowicz, Mehdi Mobli, Volker Herzig, John Gilchrist, Jordan Wagner, Graham M. Nicholson, Glenn F. King, Frank Bosmans
Nature Communications 5, Article number:4350
Abstract: β-Diguetoxin-Dc1a (​Dc1a) is a toxin from the desert bush spider Diguetia canities that incapacitates insects at concentrations that are non-toxic to mammals. ​Dc1a promotes opening of German cockroach voltage-gated sodium (Nav) channels (​BgNav1), whereas human Nav channels are insensitive. Here, by transplanting commonly targeted S3b–S4 paddle motifs within ​BgNav1 voltage sensors into ​Kv2.1, we find that ​Dc1a interacts with the domain II voltage sensor. In contrast, ​Dc1a has little effect on sodium currents mediated by ​PaNav1 channels from the American cockroach even though their domain II paddle motifs are identical. When exploring regions responsible for ​PaNav1 resistance to ​Dc1a, we identified two residues within the ​BgNav1 domain II S1–S2 loop that when mutated to their ​PaNav1 counterparts drastically reduce toxin susceptibility. Overall, our results reveal a distinct region within insect Nav channels that helps determine ​Dc1a sensitivity, a concept that will be valuable for the design of insect-selective insecticides.

I am of course glad to have my image associated with this research, even through a magazine that tries to make science palatable by using racy come-ons. Though how many readers will make it at least as far as the abstract? 

Friday, September 26, 2014

Pat and Lisa's garden in Ramsey Canyon

September 20: I spent the night after my presentation for the Master Naturalists of Cochise County at Pat and Lisa's place right next to the Ramsey Canyon B and B and the Nature Conservancy. The road towards those two properties was flooded and probably washed out.


Sierra Vista and Hereford got more than their share of rain, not just from Hurricane Odile but all summer long. The creek that seems to wash directly along the foundations of Pat's house was powerful and noisy but actually very well retained by an old wall made of cement and local rock.
During my visits I like to sleep outside in my vehicle to be closer to nature, but Pat showed me the wrought iron bird-feeder stand that their local bear had just bent over to reach some suet. The thing was not very high to begin with - so did he just pull it over it for a more convenient position while snacking? He must be brutally strong. So I slept indoors this time.

The night was cool and the morning overcast. Insect-life started slowly, but than with a bang: a male of the huge scoliid wasp that has wandered north from Mexico about five years ago visited Pat's milkweed. They are usually too active to get good photos, but this time I got even a video.
There is a whitish crab spider in the background. It fits very well with the white milkweed. It's yellow 'species mates' were ambushing prey on yellow asteraceae, usually so camouflaged that only the death pose of their prey gives them away. So do they develop their own color in accordance with the flower they live on? Do they chose a flower in accordance with their own color? Can they change color reflexively?

Euphoria sonorae
One composite disk held another surprise: the behind of a scarab beetle was protruding from it while the beetle's head was buried deeply among the florets, where the nectar flows. It's the typical position of Euphoria     .

Lintneria istar, Istar Sphinx and

The place was crawling with caterpillars. Pat's tomatoes were completely defoliated by Manducas that had already dug into the soil to pupate. But I found a large caterpillar of Lintneria istar (Istar Sphinx another sphingid. Pat's  Pipevine (not the endemic species) stood untouched, but his dill plant was adorned with a very pretty young instar of a Black Swallowtail. Pat's garden has pretty flowers and decorative plants, but most are basically insect bait. He was just planting Ground Cherry plants to maybe entice the red cousin of the Potato Beetle to move in.

Dysschema howardi
Brickelia grows all over, and the caterpillars on a plant right by the bridge over the fish pond promise to turn into the startlingly beautiful Tiger Moth Dysschema howardi (Northern Giant Flag Moth) .

Agraulis vanillae (Gulf Fritillary) and Stagmomantis sp..
Gulf Fritillaries and their caterpillars drew me to the Passion Flower at the bug room wall, but then I discovered a Stagmomantis threesome with no missing heads! They just don't always live up to their stereotypes.  

Cactophagus spinolae 
A cactus weevil Cactophagus spinolae  was strolling among the rocks. Pat gladly let me collect that one. We all know how he can mess up a cactus with those biting mouth parts at the tip of the long snout, and Pat has also seen twice that these big weevils attack and kill those slow lumbering mantis females. Who would have thought that? 


On the metal-grid walkway over that fish pond I was surprised to meet the Black-necked Garter Snake again that I had seen hiding under an Opuntia pad earlier. He was carefully choosing his diving spot to join the gold fish in the water.


An area adjacent to juniper oak forest is covered in natural vegetation. Adult Tortois Leaf Beetles were pressing themselves against the Datura leaves so that the pigmentless outer parts of their elytra and  pronotum would prevent any cast shadow that might betray them. Instead their presence was announced by the shotgun pattern of holes in the leaves that they probably produced as larvae.

Systropus arizonicus  and Bombus sonorus (Sonoran Bumble Bee)
Sweet smelling Horse-mint flowers attracted day-flying noctuid moths, a brightly colored Sonoran Bumblebee and another visitor that was flying with long, dangling hind legs: Systropus arizonicus reminding somewhat of a Polistes Wasp. It is a bee fly of rather unusual body-shape.

Monoleuca obliqua, Caterpillar photo C. Melton
Systropus arizonicus is a brood parasite of caterpillars of Limacodidae ... I wonder how it gets its eggs into those caterpillars and if the long legs have anything to do with that? They seemed of little use for nectaring... Here is a limacodid moth Monoleuca obliqua and its fantastic slug caterpillar, both from Ramsey Canyon. 

This photo of a Stinkhorn (Phallus impudicus) is from an earlier visit. This time we saw Earthstars that were larger than silver dollars, but being busy chasing my bee fly, I never got a photo.
I could have spent days in this garden paradise except that the next shower was already rolling in. The garden was also full of interesting mushrooms. They are going to grow huge this year!



Sunday, September 21, 2014

Insects of Cochise County for the Master Naturalists Program

On Friday, I gave a 3 hour 'Insect' lecture for the Master Naturalists of Cochise County. Thank you Sheri Williamson and Tom Wood (Southeastern Arizona Bird Observatory) for inviting me!

 I had no idea how well informed my audience would be. Interested, I assumed, because they are naturalists. But still, where to start? Tom introduced my talk saying that I would now show them the hundreds of species of Cochise County insects. Requests to use English names instead of scientific ones came up shortly. I guess that would have been a way to stick to 'hundreds of species' instead of tens of thousands, but it would have excluded almost everything beyond house and garden pests and the pretty ones: Butterflies, Dragonflies, Tiger Beetles. Those all got English names now, and there are good illustrated field guides to identify them. But I wanted to challenge my audience to look beyond the already well-known bugs and I certainly did not want to end up following the media rut leading to Monarchs and Honey Bees. 
 So instead of introducing insect species in pretty pictures or even the spectacular rarities of Cochise County that attract seasoned insect collectors, I had organized my talk around themes.


Not all critters that we call bugs are insects (the systematic position of insects as a class of the phylum Arthropda).


Anatomy and a touch of physiology of a typical insect. Knowing body parts and their functions helps to understand the language of field guides and to recognize special adaptations of the basic plan.  



Incomplete Metamorphosis
Life cycles, including complete and incomplete metamorphosis, followed by a short discussion of the most important orders that exhibit these traits in their development - illustrated by many examples of Cochise county insects.

Most Holometabolous Orders of Insects in Cochise County
A mimicry complex around the powerful stinger Polistes comanchus, one of our social paper wasps, is encountered among those examples.


Switching from the specifics of insect biology to their interaction with the environment:
Reasons for the extreme insect diversity of Cochise County, from the turbulent geological conditions, the location at the interface of Sonoran and Chihuahuan Desert, to the climate situation  (5 seasons) with tropical influences.

Grasshoppers representing the grasslands


Scarabs and silk moths of the sky islands

Riparian insects from the San Pedro River corridor

Tiger beetles from the dunes around the Willcox Playa
The resulting habitats of grasslands, sky islands, riparian corridor, sand dunes and salt flats are introduced with help of character species of insects and their special adaptations.

The ecological importance of insects as the bridge between primary producers (plants) and the rest of the food chain. The importance of insects as macro-decomposers in the ecological cycle.

Insect field guides - even the ones for the eastern states can be used to get to the genus, but in most cases we have different species on the west side of the Rockies. After finding the possible genus (or at least the family) in a field guide, go to the  data section of BugGuide.net (you need to be logged in for this function) to find the possible Arizona species.
 Literature and internet techniques for species identification: use your new knowledge and field guides to get close, then log into BugGuide.net, go to the group you have identified, pull up 'data' from the submenue, chose Arizona from the options under the map, then scroll down through all the identified  images until you find your species.

The talk went well. There were good questions during and after, so people were obviously following with interest. We even attracted a couple of boys from outside who snuck into the back and listened. The organizer, Tom Wood, told me that the presentation was exactly what they had been hoping for. That felt good! The only glitch was that the recording equipment wasn't turned on properly, so there is no video. Some people were truly sorry about that - they had wanted to listen to it again. I breathed a sigh of relief. Maybe this blog can help to remember the most important points.



My insect lights had been on during the talk, but the result was not too great due to the location and the mid September date. But a number of very charismatic mantids was visiting, so we had a glimpse of the excitement the light trap can provide.
       






Thursday, September 18, 2014

Between two storms and a powerpoint presentations - a visit to Annual Sunflowers

I don't have much time for insect excursions or blog writing because I am preparing a 3 h powerpoint presentation for the Master Naturalists of Cochise County on Friday, which is tomorrow. Today we were expecting Hurricane Odile to soak Arizona in deluges of rain.So I tried to be ready before possible power-outages would hit. but Odile changed southward at the last minute: no rain for Tucson.
But last Sunday I drove over to Montosa Canyon anyway. I needed some Horse Lubbers for my presentation and some Green Fig Beetles for a client.
My first stop was Amado Rd and the Santa Cruz River. A few days ago, right after Hurricane Norbert, I had seen the raging floods of that river completely fill all the space under the wide bridge of Ina Rd in Marana. On Sunday in Amado its bed was already dry again. And the Seep Willows that had been completely submersed over the weekend were now already going to seed, so I found only one single Fig Beetle.


But Annual Sunflowers Helianthus annuus were blooming. On our trips together, Eric Eaton always made sure to check what was drawn to their sap-oozing stems and leaves, often against my protest that there would be nothing but hymenopterans (wasps were what he wanted of course).


But this time there was nothing but beetles. Even the fat black bumbling things that sounded and moved very much like bees turned out to be Euphoria lateralis. Those scarabs fly with closed elytra, doing a convincing imitation of bumble bees. They were everywhere.


On the underside of flower heads and buds and also along the stems of leaves I found many specimens of three species of lady beetles. There were no aphids. The ladybugs were there for the plant juice.


 Even Fireflies like sweets - I find Pyropyga nigricans on sunflowers every year. Soft-winged flower beetles (genus Collops) were using the sunflowers as dating locale.


Sunflowers are hosts of the offspring of numerous beetle species.  I found the longhorn beetle Dectes texanus and 2 weevils that all seemed ready to oviposit on the plant. 'The right-hand weevil is Cylindrocopturus adspersus, a sunflower specialist that's an economic pest in commercial sunflower crops in the midwest. It's common in the Chiricahuas' (Henry Hespenheide). Since their larvae have to grow up within this annual plant, those three species are all very tiny, much smaller than most beetle species growing up in tree branches or even acorns.


 The leaf beetle Zygogramma exclamationes (left) lays its eggs on the tip of the plant, where the larvae will feed on the youngest, freshest leaves. I also found Zygogramma signatipennis (middle) and the tortoise beetle   Chelymorpha phytophagica  but I'm pretty sure that the latter was just visiting - it lives on a morning glory that was growing close by.


Of course, there were not really 'just' beetles. The pretty little noctuid moth Spragueia magnifica, some ants and flies and finally a flatid Ormenis saucia had joined the party.