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BERMUDA CEDAR SCALES Carulaspis minima (Targioni-Tozzetti)
& Lepidosaphes newsteadi
(Sulc.) –
Homoptera, Diaspididae (Contacts) ------ CLICK on Photo to enlarge &
search for Subject Matter with Ctrl/F. GO TO ALL: Bio-Control Cases Lepidosaphes newsteadi, a
pest of pine, cedar, Abies
and Picea of European origin,
is widespread in central and western Europe, and reported also from Lebanon
and Turkey. It was accidentally
introduced into North America and Bermuda.
The scale attacks only the needles, causing defoliation in heavy
infestations. It is univoltine in
Europe, fertilized females overwintering, then depositing an average of 31
eggs per female during the following spring.
Crawlers hatch at the beginning of June and emergence of adult males
takes place in the 2nd half of August, coinciding with the second molt of the
females (Schmutterer 1951, Balachowski 1954). In Bermuda this species also killed Bermuda cedar (Waterston
1947). With both species being
harmful to the Bermuda cedar, even in moderate infestations, and causing tree
mortality within two years after the first sign of attack, these pests
destroyed a large proportion of the trees on the island and threatened to
make the Bermuda cedar extinct. Bermuda cedars were
considered valuable for tourism, and its extermination might have serious
effect on the island economy.
Biological control was thus initiated in 1946 against both
scales. Initially introductions of
natural enemies were made mainly against L.
newsteadi, but in succeeding
years the majority of the imported species were for C. minima. The biological control effort was one of
the largest ever to be undertaken as far as numbers of species of natural
enemies released against a pest and total numbers of individuals liberated. Hemisarcoptes malus
(Shimer), a predator of oystershell scale, was introduced from Canada against
L. newsteadi in 1946.
These shipments yielded 435 adults and immature stages for field
release in Bermuda (Waterston 1947).
These were supplemented in 1949 by 235 adults of Chilocorus spp. from California bearing hypopi of the
mite, which were also released. Aphytis mytilaspidis (LeBaron), a parasitoid of oystershell scale,
was introduced against L. newsteadi from Canada in
1947. Two additional parasitoids of
oystershell scale, Anabrolepis
zetterstedtii (Westw.) and Aphytis sp., were introduced
against L. newsteadi in 1947 from Italy,
and also Chilocorus
bipustulatus (L.), a general
predator of scale insects (Rosen & DeBach 1978). In March 1947
shipments of two coccinellid predators, Lindorus lophanthae (Baisd.) and Orcus chalybeus (Bdvl.), were made
from California. Both species
appeared promising in feeding tests with C.
minima. Additional importations from California
the same year included the coccinellids Chilocorus distigma
Klug., C. stigma Say, Exochomus
quadripustulatus (L.) and Zagloba ornata (Horn), and the encyrtid
parasitoid Habrolepis
rouxi Compere. Several shipments of other ladybeetles,
collected from bamboo, coconut and citrus, were made from Trinidad, British
West Indies, in 1947, these comprising Azya trinitatis Mshll., A. luteipes
Mulsant, Chnoodes
sp. nr. cinctipennis Gorham,
Cryptognatha
nodiceps Mshall., Curinus coeruleus (Muls.), Pentilia sp.,
Poria sp.,
Prodilis
sp., and a nitidulid Cybocephalus
sp.. Chilocorus nigritus (F.) and Lindorus lophanthae, were obtained in Mauritius and liberated in
Bermuda. In all 30,000 parasitoids
and predators were imported and released by the end of June 1947. Importations in
1948 included the predators Egius platycephalus
Muls. and Chilocorus cacti (L.) from Puerto Rico, C. bipustulatus
from France, and the parasite Aphytis
sp. (Chinese origin) from California.
Additionally, many of the species obtained in 1947 were released again
in 1948, including large numbers of Hemisarcoptes
malus. A program of mass
producing coccinellid and nitidulid predators for the Bermuda project was
conducted in California during 1948-49.
Shipments of the coccinellids Cephaloscymnus
occidentalis Horn, Chilocorus bipustulatus, Lindorus
lophanthae, Lotis nigerrima Casey, L. neglecta Muls., Microweisia
saturalis (Schwarz), Pharoscymnus
exiguus (Weise), Telsimia nitida Chapin, and Zagloba ornata, and the nitidulid Cybocephalus sp. (Chinese origin) were made during this
period. About 318,000 individuals
were received from California during 1949.
A similar program was started in Bermuda, and 134,000 predators were
reared and released there during that year. Shipments of Pinus sylvestris foliage, heavily infested with Leucaspis newsteadi
and Leucaspis loewi Colvée, were received
from Switzerland in 1949. Of the
parasitoids obtained from these shipments, 1,048 Prospaltella aurantii (How.) and smaller
numbers of Aphytis mytilaspidis and Azotus sp. were released
against both L. newsteadi and C. minima. Mass
production of predators was continued in California and Bermuda in 1950. An additional species of Cybocephalus (South African
origin) was obtained from California.
Further introductions included Chilocorus
bipustulatus, Scymnus sp., and Cybocephalus
rufifrons Reitter from
Portugal, Chilocorus stigma from Florida, and small
numbers of the coniopterygid predator Semidalis aleyrodiformis (Steph) from
England. Predatory
coccinellids that were liberated in 1951 from shipments received from
Trinidad were Azya trinitatis, A. luteipes, Curinus
coeruleus, Delphastus
diversipes (Champ.), Zenoria revestita Muls., Pentilia insidiosa Muls., P. castanea Mulsant, Psyllobora
confluens (F.), Cryptognatha nodiceps, C. tumidiventris Champ, Exochomus
bisbinotatus Gorham, Chnoodes sp.,
Scymnus sp.,
and at least three unidentified species.
Shipments from Jamaica comprised Chilocorus
cacti, Exochomus jamaicensis Sic., E. ritchieri Sic., and Procula douei Muls., as well as Cycloneda
sanguinea (L.) (an aphid
feeder) and Scymnus sp. (a
mealybug feeder). Of these, C. cacti was mass produced in Bermuda. Shipments of coccinellids, collected in
Florida on juniper trees infested with C.
minima and other scales,
yielded Chilocorus stigma, Microweisia misella (Lec.), Cleis picta (Rand.), Cycloneda
sanguinea, Coccinella
novemnotata Hbst., and one
unidentified species. Predators that were
mass produced in California and forwarded to Bermuda during 1951 were Lotis nigerrima, L.
neglecta, Zagloba ornata, Pharoscymnus
exiguus, Cephaloscymnus
occidentalis, Lindorus lophanthae, Pentilia
insidiosa and Cybocephalus sp. (Chinese
origin). The work was
terminated in 1951 when the majority of cedar trees in Bermuda were dead or
in the process of dying. Altogether
over 50 species of predators and parasitoids were introduced into Bermuda
during 1946-51. Almost 700,000
predators were mass produced in California (1948-51), and more than 1,700,000
were mass produced in Bermuda for release against the cedar scales (1949-51)
(Bedford 1950, Thompson 1954, Bennett & Hughes 1959). Lepidosaphes newsteadi which
was originally considered the most dangerous pest of Bermuda cedar, declined
rapidly and was almost completely displaced by C. minima
by the end of 1948. The causes of
this remarkable decline are not known.
The introduced predatory mite, Hemisarcoptes
malus, and a chytrid fungus,
Myiophagus ucrainica, as well as
competitive displacement by C.
minima are thought to be
possible causes. Hemisarcoptes malus
was reported by Bedford (1950) to be established in Bermuda, although not in
infestations on Bermuda cedar.
Whatever the cause, L.
newsteadi became very rare
in Bermuda after 1948, except for an occasional isolated infestation. Carulaspis minima
covered the islands and infested practically every Bermuda cedar tree by the
end of 1948. Of the numerous natural
enemies that were introduced against this scale, only a few were permanently
established. Lindorus lophanthae
was one of these and increased rapidly, spreading to all parts. It seemed abundant and effective at
times. Microweisia saturalis
was also established, and became abundant in the western areas of the
islands. Hemisarcoptes malus
was recovered in 1956 from C.
minima. Several other species were recovered some
time after their release, and were reported to have reproduced in the field,
but most eventually died out. A few
species became established on various other hosts, but were unable to breed
on C. minima. Severe
hurricanes in the autumn of 1947 and 1948 probably contributed to the failure
of many species to become established, and hastened the decline of Bermuda
cedar trees by causing severe damage to the foliage. Predation by lizards (Anolis spp.) was suggested by Simmonds (1958d) as another
possible factor in the failure of introduced coccinellids to become
established in Bermuda. Although L. lophanthae and M.
suturnalis showed some
promise of controlling C. minima wherever they became
particularly abundant, the decline and eventual death of many infested trees
was not prevented. The main objective
of the project was to prevent the destruction of the natural forest, but this
was not realized. Bermuda cedars were
not completely eradicated, however, as healthy stands may still be found in
certain parts of this extremely small group of islands. Seedings germinate in many areas. It is not known whether the survival of
Bermuda cedar has been affected to any extent by the numerous natural enemies
of C. minima introduced into the islands (Bedford 1950, Thompson
1954, Bennett & Hughes 1959).
According to Thompson (1954) the results of the project have shown
that predators may be much more host specific than generally thought. Rosen & DeBach (1978) wondered whether
the failure of the project was not partly due to the fact that C. minima, the main target, was at that time misidentified as
C. visci. Also the
emphasis on predators to the near disregard of parasitoids may have been
responsible for the lack of parasitoid establishment. Carulaspis
is known to be commonly attacked by Aphytis
sp. in Greece and California (DeBach 1946, Rosen & DeBach 1978). The release of Azotus sp. is if particular interest
as all the known species of that genus were thought to be
hyperparasitic. (Also see Anonymous
1948, Bedford 1949, Waterston 1946). REFERENCES: [ Additional
references may be found at: MELVYL
Library] Anonymous. 1948. Plant pathology. Bermuda Rept. Dept. Agric. 1947: 10-12 (Abs. in REv. Appl. Ent. (A), 39:
148) Balachowsky,
A. 1954. Les Cochenilles Paléarctiques de la Tribu des Diaspidini. Inst.
Pasteur, Paris. 450 p. Bedford, E. C. G.
1949. Report of the plant
pathologist, 1948. Bermuda Dept.
Agric. Rept. 1948: 13-24. (Abs in
Rev. Appl. Ent. (A), 39: 148). Bedford, E. C. G.
1950. Report of the plant
pathologist. Bermuda Dept. Agric.
Rept. 1949: 11-19. (Abs. in Rev. Appl. Ent. (A) 39: 148.) Bennett, F. D. & I. W. Hughes. 1959. Biological
control of insect pests in Bermuda.
Bull. Ent. Res. 50: 423-36. Borkhsenius, N. S. 1950. Unarmored and armored scales of the
U.S.S.R. (Coccoidea). Akad. Nauk
S.S.S.R., Opred. Faun. S.S.S.R. 32:
1-250. DeBach, P. 1964. Some species of Aphytis Howard (Hymenoptera: Aphelinidae) in Greece. Ann. Inst. Phytopath. (Benaki) (n.s.) 7: 5-18. McKenzie, H. L. 1956. The Armored Scale Insects of
California. CAlif. Insect Survey
Bull. 5. 209 p. Rosen, D. & P. DeBach. 1978. Diaspididae. In: C. P. Clausen (ed.), Introduced Parasites
and Predators of Arthropod Pests and Weeds:
a World Review. U. S. Dept.
Agric., Agric. Handbk. No. 480. 545 p. Schmutterer, H. 1951. Zur Lebensweise
der Nadelholz-- Diaspididen (Homoptera, Coccoidea, Diaspididae, Diaspidinae)
und ihrer Parasiten in den Nadelwäldern Frankens. Ztschr. f. angew. Ent. 33: 111-36. Simmonds, F. J.
1958. The effect of lizards on
the biological control of scale insects in Bermuda. Bull. Ent. Res. 49: 601-12. Thompson, W. R.
1947. Interim report on two
scales attacking the Bermuda cedar.
Bermuda Dept. Agric. 3 p.
(Abs. in Rev. Appl. Ent. (A), 38:
85). Thompson, W. R.
1954. Biological control work
on cedar scale in Bermuda. In: 6th Commonwealth Ent. Conf. Rept., London: 89-93. Waterston, J. M.
1946. Report of the plant
pathologist (Bermuda) for the year 1945.
Bermuda Dept. Agric. 12 p.
(Abs. in Rev. Appl. Ent. (A), 36:
48). Waterston, J. M.
1947. Report of the plant
pathologist (Bermuda) for the year 1946.
Hamilton Dept. Agric. 18 p.
(Abs. in Rev. Appl. Ent. A), 37: 37). |
