Biological Controls and Phylloxera
Yellow phylloxera mite eating root of grape plant.
Phylloxera almost wiped out grapes in Europe in 1860-1880.
Two schools of research emerged; use of resistant America grape plant as roostock and possible use of biological controls.
C V Riley 1868 researched biological controls and I received the following from Edward Smith.
Edward Smith, CV Rileys Biographer kindly dug out the following research for me by CV Riley on phylloxera. 1868. This research lead to the conclusion that american rootstock was the answer to phylloxera.
It appears no recent research has been done since 1876 on phylloxera natural enemies! Edward Smith comments-
"I am pleased to have had time to get back to C.V.Riley and
his notes on natural enemies of the Grape Phylloxera. Riley published nine annual
reports as Missouri State Entomologist (1868-76). While these contain considerable info on grape pests, control measures, etc., he has very little
on
Tyroglyphus. I find notes in reports VI, 52-55, 81 and VII, 106:
Copies accompany this letter. I was advised some years ago by individuals
at the Montpelier School of Agriculture that there are extensive
records on root stocks that Riley sent to the team of brothers-in-law, J. Lichtenstein and J. E. Planchon. According to them, these records have not been thoroughly researched.
I was invited to study them but was unable to accept the invitation. Surely
someone at the Montpellier station must have studied the status
of Tyroglyphus in the years since Riley called attention to it. With all the interest in Phylloxera where ever grapes are grown,
one would expect that an international center would have arisen
to collect and share data.
Such speculation is beyond the scale of your request to me.
Best regards,
Ed Smith"
Sixth Annual Report of the State Entomologist. (C. V. R.)
pg.52
The enemies known to attack the Phylloxera underground
are, naturally enough, fewer in number. In one instance I have found
a Scymnus larva at the work six inches below the surface, and there
is a Syrphys fly (Pipiza radicum, W. & R, Fig 15), whose larva
lives under-ground and feeds both on the Apple-tree Root -louse,
and on this Grape Root-louse. Wonderful indeed is the instinct which
teaches this blind larva to penetrate the soil in search of its
prey; for the egg must necessarily be laid at the surface. But though the uder-ground enemies of its own class are few, I have
discovered a mite which preys extensively upon this root-inhabiting
type, and which render efficient aid in keeping it in check in this
country.
This mite (Tyroglyphus phylloxeræ, Planchon &
Riley, Fig. 16), belongs to the same genus (17) as the cheese and
meal mites (T.siro Linn.), and the species (T. entomophagus Laboulbène)
which infests preserved insects and is such a pest in cabinets.
As is the rule with mites, it is born with but six legs, but requires
eight after the first or second molts. It varies considerably in form,
with age, and in studying it with a view of distinguishing it specifically
from other described species, I have noticed all the different tarsal
characters shown as d, f, g and h (Fig. 16), and on which distinct
genera have been founded. Mites present themselves in such different
forms that the adolescent stages of the same species have been made to represent distinct families
by authors who never studied the development of these beings. Thus
the genera Astoma, Leptus, Claris, Myobia, etc., are now known to
be but the larval forms, some of them commonly met with as such
but not yet connected with the more perfect and mature forms.
The different species of Tyroglyphus, so far known, prey on vegetal and animal substances, particularly when these are in a decaying or putrescent condition. In one of their forms (Hypopus) they are also known to be externally parasitic on living animals. The species under consideration combines both habits, as when young it mostly contents itself with the altered sweets of the roots which rot from the punctures of Phylloxera, while when older it preys by preference on the lice themselves.
pg. 53.
A singular feature in the life-history of many of the species of
the genus Tyroglyphus is the fact that under certain conditions
an entirely different form, with a hard brown chitinous covering
or shield and characterized by Dugès as new genus by the
name of Hypopus, develops within the softer body and finally issues
from it by splitting open the softer skin.
Claparède *, who believed this form to be the male, has carefully
described and figured the process of change in the European Hypopus
Dujardinii, and that Tyroglyphus phylloxeræ has its Hypopus
form was independently proved by Prof. Planchon, and myself -- the
letters announcing the observations on either side having crossed
en route. Hypopus, as already stated, has been found preying upon
living animals. Tyroglyphus is a slow traveler, and with its soft
body cannot endure exposure to the air, or resist the attacks of
other minute animals. Yet it is ubiquitous, living both above and
below ground and swarming on decomposing animal and vegetable substances.
When these have been consumed or reduced to dry powder, what becomes of the swarming mites? M. Maguin has, I think, rightly answered the question. All adult and old mites, together stage, the octopod larvæ, perish; but those in the adolescent stage, the young hexapod pupæ, are preserved by their power of putting on a coat of mail which protects them against external influences until they can attach themselves to some living and moving animal, (flies, beetles, spiders, millipeds, and larger animals), which become their carriers and transport them to places which they could otherwise never reach, and where, finding appropriate food, they throw off the disguise and breed as Tyroglyphs, with their well-known fecundity.
Associated with this predaceous mite, I have found another (Hoplophora arctata Riley, Fig 1.), of very curious form, reminding one strongly of a mussel, and I refer to it in this connection because I once strongly suspected it like-wise to be, in some way, related to the soft-bodied Tyroglyphs. In studying these mites and their habits, I had frequently filled vessels with grape roots from which all by Tyroplyphs and Phylloxera had, to all appearances, been carefully excluded; only to find, on subsequent examination, a number of these mussel-like Hoplophoras and a corresponding decrease in the number of Tyroplyphs.
*Studien an Acariden, Leipzig,
1868
Pg. 54
This happened more especially in the fall of the year, and I could not help suspecting that the former might prove to be a winter or hibernating form of the latter. There is so much yet to learn of the polymorphism of mites that the suspicion may yet prove justifiable. But with our present knowledge it is safest to explain the facts above stated on the ground that the Hoplophoras were at first buried, and consequently invisible, within the roots examined, and that the decrease in the number of Tyroglyphs was owing to death and other causes -- an explanation which is all the more plausible from the fact that I subsequently found the same narrow-bodied Hoplophora swarming in decaying cottonwood logs. Hoplophora (meaning armed or weapon-carrier) is an anomalous genus belonging to a curious family of mites (Oribatidæ), distinguished, as Nicolet well sets forth, from all other families by having a hard covering which is analogous to that of many hexapods, but less elastic or yielding, so that, while resisting a great degree of pressure, when it once gives way it cracks and fractures with the brittleness of glass.
These coverings are differently formed and sculptured and frequently ornamented with protecting spines. The mites of this family are also distinguished from other mites by their organs of respiration which are at the superior base of the cephalothorax and look like eyes, being rounded elevations surmounted by hair. The family comprises two great divisions: First, those which in the larva state have a form and appearance widely different from those of the adult, which are assumed only at the last molt. Second, those which are born more in the image of the adult form, to which they gradually approach by each successive molt.
The genus Hoplophora, according to Nicolet, is further anomalous by being born with eight legs, whereas all other mites, even those of its own family, are born with but six; Claparède, however, shows that at least one species (H. contractilis) is hexapod before the first molt. Another peculiarity belonging to it is the mobility of the cephalothoracic shield which closes over the abdomen and fits tight like the lid of a box, whenever the animal withdraws its head and limbs, which it does on the slightest disturbance. Indeed, the hardened body-covering is admirably constructed for the purpose of protection. It is composed of three principal parts, the thoracic lid, a superior piece covering the back, the sides and the posterior portion of the body, and a ventral piece, more narrow, rounded behind, and divided in four by slits which form openings for the protrusion of the anal and genital organs.
The species under consideration differs from all others described in the form of the horny covering, which is so narrow that the animal topples over on its side the moment the limbs are withdrawn.
Pg. 55.
Since the discovery of this Phylloxera-feeding Tyroglyph in America, numerous sensational and exaggerated newspaper articles have appeared, glowingly describing how the French vineyards are to be saved from Phylloxera ravages by the introduction into France of this its enemy; and I have received several orders from Europe for supplies of the cannibal. Prof. Planchon, it is true, will attempt to introduce it, and we may hope with success; but from what is here said, it is evident that the enthusiasts who expect so much are doomed to disappointment.
Seventh Annual Report pg. 106
Natural Enemies
It appears pretty certain that the mite I described last years as preying on Phylloxera, is likewise found in Europe; or at least a species that cannot well be distinguished from it. Thus during the year, M. A. Fumouze, an authority on these minute animals, has published some notes showing that he has found this same Tyroglyph on roots affected with Phylloxera in France, and that it is apparently the T. echinopus described by himself and Ch. Robin in the Journal de l'Anatomie et de la Physiologie, in 1868. Prof. L. Rosler, of Klosterneuburg, Austria, also announced to me by letter that he has found and studied both Phylloxera Mite and the Mussel-shaped Mite (Hoplophora arc) on the infested vines of that place. He has also observed, in addition, the larva of a Lace-wing (Chrysopa) and the Myriapodous Pollyxerus cagurus preying on Phylloxera under-ground. In addition to the Weeping Lace-wing mentioned last year, I have this year reared the Consumptive Lace-wing (Chrysopa tabida Fitch) from larvæ preying on the fall-lice.
In reference to the heteramorphism of these mites M. Méguin
states* the Hypopus, Homopus and Trichodactylus are but heteromorphous
pupæ of different species of Sarcoptides, and among them of
Tyroglyphus. He proved that, as Claparède observed in the
aquatic Atax, a new individual is formed under each skin, and all
the parts are developed anew, and not simply drawn out of their
old envelopes, as was formerly supposed.
* Comtes Rendus de l'ac. des Sc., Paris June 8, 1868.