Tuesday, May 25, 2010

A Weevil for the Biological Control of Tamarisk


Since their introduction to the US from the Mediterranean and Asia several Saltcedar or tamarisk species, especially Tamarix ramosissima, developed into noxious weeds of riparian areas. In these valuable, but often fragile biotopes, tamarisks are replacing native willows, poplars and alders at an alarming rate with fast growing monocultures. So far there are no controlling natural enemies. In Arizona, solid stands of tamarisk can be seen for example at the Colorado River at Yuma and the San Pedro River at Benson.


Research and politics:
Researchers have studied tamarisks in Asia and Europe to find organisms usable as biological control of the spreading weed. Among the 'pests' that are tied to the tamarisk by close co-evolution in Asia and Europe (and thus would hopefully not attack any hosts other than tamarisk if introduced to the US), is the weevil Coniatus tamarisci. Efforts to get approval for its release here were underway for years, but were counteracted by naturalist groups mainly focused on birds because rare Willow Flycatchers are nesting in the tamarisk thickets. The United States Department of Agriculture claims not to have released the weevils from strict quarantine.

Field observations:
Last fall fellow arthropod researcher Jillian Cowles showed Charles O'Brien, our world expert on weevils, photos of a pretty little bug that she'd found on tamarisk bushes in Vail, Arizona. Charlie and Jens Prena recognized it as Coniatus splendidulus. This was the second time this species was found in the US, Charlie had received specimens from Phoenix, AZ in 2006.

So far we don't know how it got to the US. Could it have hitchhiked on a transport coming back from the war in Irak? This spring, it was found in Gilbert (Maricopa County), as well as along the Santa Cruz River from Marana (NW Pima County) to Amado (Santa Cruz County). The beetles fly well and will spread quickly, it seems.






Live Cycle: here's a video of a mating attempt




Mating pair in early May 2011

Adult beetles hibernate in soil and litter close to the trees. In Arizona, they climb the trees by the end of March, feed on fresh shoots, mate, and begin laying their eggs in early April. The image shows an unusually dark male competing for access to the female, and an egg in the lower right corner. Eggs are usually placed in a cavity that the female chews and then covered with the chewed material. Oviposition as shown here sometimes occurs in captivity or under stress.



From mid April to early May larvae were feeding on leaves and flowers together with the adults. They live free and unprotected on the surface of the plant, an unusual strategy in weevils.















When they are ready to pupate the larvae spin retinous web cocoons that serve as protective cages. They place them in the open at the tips of twigs, sometimes in clusters. Larvae, and then later pupae, can be seen wiggling inside through the loose mesh.















By mid May most have emerged as beetles. From Asia, Kovalev describes two generations per year. Here in Arizona there may be time for one more, or the beetles may take an aestivation pause during the dry hot season that's approaching.












At the Santa Cruz River the beetles seemed to prefer immature young trees. These hosts appeared clearly set back in their development compared to beetle free trees.





P.s.: Another tamarisk 'pest' the leaf beetle Diorhabda elongata is being released since 2004 in Utah and Colorado. Check this site for more info

P.p.s.: Diorhabda elongata, Trabutina mannipara (Mealybug) and Coniatus tamarisci were approved for release in 1996 Check here for more info. Only the leaf beetle was eventually released, but not in Arizona and New Mexico, where the Willow Flycatcher was found breeding in tamarisk.


Literature:
Kovalev, 1995, Co-evolution of the tamarisks (Tamariceae) and pest arthropods () with special reference to biological control prospects. Proceedings of the Zoological Institute of the Russian Academy of Sciences. St. Peterburg, vol. 259
Dudley, T.L. 2005, Progress and pitfalls in the biological control ofSaltcedar (Tamarix spp.) in North America. Proceedings 16th USDA interagency forum on Gypsy Moth and other invasive species

Wednesday, May 19, 2010

A Young King

My husband Randy inadvertently cornered this beautiful little snake on our terrasse. I think it is a very young Kingsnake, Lampropeltis getula. If so, this one will grow up to become a formidable constrictor, able to take on and devour any rattlesnake. He's immune to rattler venom.
I've found adult Kingsnakes around here, but they are never patient enough to have their picture taken. I remember that they were all of the banded pattern, called California Kingsnake. This one has the dorsal spots of a Desert Kingsnake, but according to the distribution in the literature we seem to be too far north west here (NW Bajada of the Tucson Mountains). I will get expert help to exactly identify the snake from these photos.




The snake made his way straight up the brick wall and disappeared in the foliage of a bush of Barrio Petunias.













Hope to see him again!


P. S.
Here is what the experts said:

Brendan O'Connor: 'Wow that's a unique one for sure. Looks like a desert kingsnake but I can't say I have ever seen one quite like that before. Great find and photo.'

Stephane Poulin: 'There is a lot of variation in kingsnakes but this one is a common kingsnake not a desert one.
Nice photo it is a beautiful specimen'

Pat Sullivan: 'Your kingsnake: is an aberrant color pattern, probably of a California ("desert color phase" = black and white bands). I haven't seen this pattern before. I wonder if it occurred naturally? Are there any snake breeders in your area? It could be an escapee from a breeder (or from breeder's stock).'

Manny Rubio: 'Wow! That is one spectacular kingsnake. I sure wish you'd kept it. It is a yearling and-- as others have said-- very unusually patterned and has exceptionally bright wide wide markings.. If it reappears-- call me!'

So it seems the experts agree that this snake is unusual.

Tuesday, May 18, 2010

Bugs and Beetles from Aravaipa Canyon

Last Sunday we had visitors from Texas and Germany who were mostly interested in mantids and ants. May is by no means the best time to find either. Mantis nymphs are still tiny and ants are not swarming, so their queens are deeply entrenched under their mounds and layers of rock and caliche. Turns out the two guys couldn't visit later in the season because of the impending Soccer World Cup.


We decided to go to Aravaipa Canyon in Pinal County, AZ. We had no time to get permits for the actual Wildlife Preserve and instead stayed in the more open, less dramatic western part of the canyon. This area only hints at the dramatic beauty of the deeper chasm of the preserve, but is still very attractive with it's year-round running creek.

Following is just a pictorial list of insects that I was glad to find, even if most of them weren't first sightings.



Beetles, Coleoptera

Griburius montezuma, Glyptoscelis pubescens, Disonycha alternata, Plagiodera arizonae, all Chrysomelidae
Necrobia rufipes Cleridae, Ulus crassus Tenebrionidae, Lixus semivittatus CurculionidaeCanthon sp., Aphodius haemorrhoidalis, Aphodius vittatus, all Scarabaeidae
Olla-v nigrum Coccinellidae, Chrysobothris sp. Buprestidae, Cymindis sp. Carabidae, Laemosaccus sp. Curculionidae




True Bugs, Heteroptera
unidentified Mirid, Ochrimnus sp., Lygaeidae, Gelastocoris oculatus, Gelastocoridae


Crophius sp., Oxycarenidae, Leptoglossus clypealis, Coreidae, Rhopalus tigrinus, Rhophalidae, Neurocolpus arizonae, Miridae


More little Toad Bugs to come!


Collecting Methods

We found all these critters by whacking bushes over a beating- sheet, fishing around in muddy algae, turning over the leathery corps of a long dead cow, going through dung of very much alive cows...the usual.

One of our group, though, showed his true dedication by trapping an over four-feet-long snake in the leg of his trousers. Luckily only one and a half feet went up, and luckily it was only a Gopher Snake.

Saturday, May 15, 2010

Squirrel's Revenge?

As a biologist, I deeply dislike anthropomorphic interpretations of animal behavior. To me it's far more intriguing to try to understand animal behavior in its own context.
Here are some interesting interactions between prey species and predator.

'Herpers' who feed live rodents to snakes can attest to the fearless indifference of many store-bought rats and mice towards snakes. In contrast, wild, experienced rodents seem to be anything but indifferent towards rattlers. But terror and caution are not the only reactions.
I once observed Round-tailed Ground Squirrel running up to a rattler that was sliding towards the squirrels burrow. The agitated rodent (tail flicking and vocalizing) approached the snake several times and came within easy striking distance. The snake ignored him and determinedly slithered into the burrow entrance, leaving the fussing squirrel behind.




Today, loud mobbing calls came from the ground feeder for birds in front of my window. Quail were pointing with greatly elongated necks. Thrashers were fanning their tails and Doves were lifting their wings menacingly. All the birds were apprehensive and jumpy, but stayed in striking distance - of a Diamond-backed Rattlesnake.





The snake ignored them, crawled into the cool shade by the bird bath and settled to stay. Its eyes were filmed over and blue - it may have been pre-occupied with molting.






But it was now inside our dog-run and very close to our patio. So with my snake stick, I moved him into a container and carried him about half a mile away from the house. His tail markings told me that he's an old acquaintance - I'd carried him away before.



When released, he took off quickly. May he stay away this time.








When I returned to my window seat there was another commotion. I had dropped the green snake stick where I caught the snake. Now a Harris' Antelope Squirrel was sniffing intently the tip of the stick. The snake end. The end that scares my dogs as much as a live rattler. The end that even smells of snake to my insensitive hay-fever impaired nose.












The squirrel then crawled around where the snake had been coiled. Followed the still visible tracks. Laid in the sand where the snake had rested. Came back to the snake end of the stick at least four times, sniffing, tail flicking excitedly, and ignoring my camera. (These guys are not tame and usually rather unapproachable.)







Then - finally - he jumped the noose end of the stick and started kicking, clawing and biting it. Leaving his toothmarks all over it (click to enlarge).

What the???

Wednesday, May 12, 2010

Green Heron at Agua Caliente

On May 5, after a long hot day of bug-hunting up and down Sabino Canyon, Eric Eaton and I decided to end the day with a stop at Tucson's beautiful palm-studded desert oasis Agua Caliente.


























Against the light of the setting sun, Eric spotted the sillouhette of a small Heron crouched on a dead branch over the still water. At first he even doubted that it was a bird at all because it was so motionless.





















The heron was intensely focused on his fishing. Ever now and then, his pose would freeze even more, he'd lean forward in nearly imperceptible increments until it seemed impossible that he would keep his balance. Only his strong, very long toes made this acrobatic stunt possible. Eventually, his head would shoot forward and the sharp beak would grab a small fish. While we watched he never missed once...



The birds at Agua Caliente are used to visitors and not too shy. I still think we were lucky that this guy stayed out in the open when we slowly circled around for better light and then were even joined by a third photographer.
The right angle of warm evening light and the overall golden hues of the still water of the lake with reflections of huge old Palms all came together to perfectly show off the jewel tones of the heron's breeding plumage.

Friday, May 7, 2010

Rare encounter: A Mojave Rattler


We live in the Bajada of the west side of the Tucson Mountains. Yesterday morning my husband Randy, our dog Cody, and I went to the eastern part of our property to check out the blooming chollas. A Desert Iguana Dipsosaurus dorsalis was bobbing his head in a territorial display. They aren't very common here and I'd found one of them dead this spring, so we were very happy to see this one.

Then the short dry grass right behind the big lizard moved and a snake slithered by, not two feet from him. The very straight movement identified it as a rattler, other snakes move in a more undulating manner. Where lacy Creosote shadows and its own markings made it nearly invisible, it flattened itself to the ground. Snakes, who have no sternum, actually spread their ribs to do so. This pose allows them to absorb a maximum amount of heat from the warm sand and from the radiation of the sun. It eliminates most of the cast shadow which hides the snake even better.
This snake turned out to be a female Mojave Rattler, Crotalus scutulatus. Thanks, Brendan O'Connor, for verifying my identification which was based only on the wide white /narrow dark bands of the tail. More reliable diagnostic markers are the facial scales and the band that runs from the eyes to the corners of the mouth. I didn't want to get close enough to record those with my 50 mm Macro lens.

We left the rattler alone - with trepidations. Rattlesnake venom is mostly haemotoxic, extremely painful but rarely deadly to larger animals and humans. But with squirrels becoming more and more immune to it, Mojave Rattlers co-evolved by producing a neurotoxic venom component known as Mojave Type A toxin- which puts them in the same class as the deadly Cobras.
This snake had a very small rattle for her 2.5 foot body length. A rattler adds a section to its rattle each time it sheds its skin which happens several times per year. This one must have broken off parts of it. She also never bothered to rattle even though I was very close.



Cody was strolling around but never noticed her. He is snake trained (the hard way) and he flinches even from black and white ribbons, curved branches, or the smell of my snake stick. Occasionally he's fooled by a Gopher Snake. He has a clearly recognizable, rhythmic 'snake bark' that will alert me from my deepest dreams. Rolling out of bed, grabbing some shoes, the snake stick and a flash light, then locating and holding the snake until Randy arrives with a container, has become the routine of hot summer nights when the snakes seem to follow the walls of our house right to the patio and the dog beds. The following morning we carry the captive out to the adjacent State Land for photo shoot and release. From May to September last year we had to move 14 Diamondbacks from patio and dog-run. Elsewhere on our property we leave the snakes alone and appreciate them with the rest of 'our' wildlife.
Western Diamondbacked Rattler
Crotalus atrox