Experimental & Applied Acarology,
14 (1992) 89-94
Elsevier Science Publishers B.V., Amsterdam
Specificity of a strain of
(Zygomycetes: Entomophthorales) to
Mononychellus tanajoa ( Acari:
G.J. de Moraes a and I. Delalibera Jr. b
aCNPDA/EMBRAPA, Jaguariuna, SP, Brazil
bCPATSA/EMBRAPA, Petrolina, PE, Brazil
(Accepted 16 December 1991 )
de Moraes, G.J. and I. Delalibera, Jr., 1992. Specificity of a strain of
Exp. Appl. Acarol.,
sp. is commonly found infecting the cassava green mite,
dar), in parts of northeast Brazil. The introduction of this fungus into other regions requires the
knowledge of its specificity, especially in relation to natural enemies of different cassava pests. Labo-
ratory tests indicated the development of germination tubes of
in some females of
Tuttle et al. and T.
Koch, with subsequent formation of a reduced number of
hyphal bodies in some T.
No females of the phytoseiid predators
mark & Muma) and
Garman & McGregor s.1. were infected by
The work reported in this paper is part of an on-going project about the
biological control of the cassava green mite,
dar). This mite is native to South America and was first reported in Uganda
in the early 1970s, from where it spread over most cassava-growing areas of
Africa (Yaninek, 1988). The considerable damage it caused in Africa
prompted the search for effective natural enemies in its area of origin.
Field surveys conducted in northeast Brazil indicated that
was a common pathogen ofM.
in areas with average annual precipi-
tation between 700 and 1300 mm. The fungus was first found in the central
part of the state of Bahia, and then detected over a wide area covering almost
all states of the region (Delalibera et al., 1992).
has also been re-
in Venezuela (Agudelo-Silva, 1986) and
Correspondence to: G.J. de Moraes, CNPDA/EMBRAPA, 13820-Jaguariuna, SP, Brazil.
0168-8162/92/$05.00 9 1992 Elsevier Science Publishers B.V. All rights reserved.
90 G.J. DE MORAES AND L DELALIBERA JR.
Colombia (Alvarez Afanador, 1990). However, it is not known whether the
same or different species of the fungus are involved, because of taxonomic
uncertainties in this group (Humber et al., 1981 ).
Unpublished evidence indicated the desirability of further exploring the
possibility of introducing a strain of
sp, in Africa for the control
However, before the introduction is accomplished, several
studies are necessary, including the determination of the specificity of the
fungus, making sure that it does not affect beneficial organisms.
METHODS AND MATERIALS
The ability of a strain of
sp. to infect the phytophagous Tetra-
Tuttle et al. and T.
Koch, and the pre-
Amblyseius idaeus (Denmark
& Muma) and
Garman & McGregor s.1. was compared in the laboratory with the ability
are common species on different crops
in northeast Brazil, while both
species are the most common pre-
in that region. Cassava leaves with
sp. were collected from Piritiba, Bahia, put in paper bags inside
a cool-box and conducted to the laboratory. Healthy
lected from cassava leaves in Petrolina, Pernambuco.
taken from recently infested cassava plants from a greenhouse, while T.
were taken from colonies maintained for at least 2 years on bean plants in
a greenhouse in Petrolina.
were collected from cassava in
Capita Grosso (test 2) and Jacobina (test 3 ), both in the state of Bahia.
s.1. were collected on the same host in Cruz das Almas,
Bahia (tests 4 and 5 ) and Bacabal, Maranhao (test 6).
Upon arrival in the laboratory, mummified infected females of
were collected and stored in glass vials (0.5 cm diameter• 6 cm long), each
containing a clump of cotton sucked in glycerol to keep the humidity low
inside the vials. The vials were kept in a refrigerator (ca. 10~ for up to 5
months before the mites were used.
Two mummies taken from the vials were put in the center of opposing halves
of a disk of cassava leaf (2 cm diameter). The disks were put inside a plastic
tray ( 19 cm diameter)< 3 cm high) containing a piece of water-saturated foam-
mat, that was in turn put inside another tray (23 cm diameter)< 6 cm high)
containing 500 ml of a saturated K2Cr207 solution, and maintained at 24~
The top of the larger tray was closed tightly with a piece of plastic material
(Magi-pack | ). This procedure should provide an ambient RH of ca. 98%
(Winston and Bates, 1960). After 48 h, the disks were observed under a dis-
secting microscope to assure that sporulation had occurred. Each disk was
transferred to plastic rearing units (2 cm diameter X 1.6 cm high) containing
a piece of wet filter paper on the bottom. One-day-old adult females of the
SPECIFICITY OF NEOZYG1TES TO MONONYCHELLUS
species to be tested were subsequently put inside the rearing units containing
the mites with the sporulating fungus. Ten tetranychids or two phytoseiids of
either species were put in each rearing unit. Ten replicates were used in each
test. The rearing units were maintained at 29 _+ 4~ and 75 + 25% RH for 2
days. That temperature favored the mobility of the mites, facilitating contact
with the fungus and consequent infection. After this period, the mites were
transferred to new rearing units, containing the disks of cassava leaves but no
mummies, and maintained at 25 _+ 1 ~ and 65 _+ 10% RH. At that tempera-
ture mites could survive adequately, and the leaf disk was maintained suita-
ble for over 2 days. Repeated transferrals of the mites to new rearing units
were done every third day until the end of the observation period.
s.1. were fed a surplus of all stages of
whenever transferred to new units.
All mites that died during the observation period as well as the remaining
live mites at the end of the period were mounted in lactophenol/Aman blue
to evaluate the level of fungus infection.
RESULTS AND DISCUSSION
The method used in storing
sp. was adequate for the purpose of
this study. Ca. 75% of the mummies sporulated after being stored for 9 months
(n=20), producing an average of 639 conidia (256-991) (n= 10) per
mummy, spread in an area of ca. 0.4 cm 2 around each mummy.
The procedure employed resulted in reasonable levels of infection of M.
(Table 1 ). Except for test 2, mortality was always nearly
zero during the first 2 days of observation, but increased considerably after
that period. Nearly maximum mortality was achieved in test 1 at the fourth
day and, for this reason, all further tests were conducted for only 5 days.
had its hemocoel most often filled with
hyphal bodies. The overall percentage ofM.
with hyphal bodies var-
ied between tests from 20.4 to 79.5%, with a general average of 56.8%. In
addition, 4.2 to 20% (general average of 14.1%) of all
of each test
had germinating capilliconidia adherent to their legs, although that did not
result in the development of hyphal bodies. Apparently, those cases corre-
sponded to unsuccessful infection, considering that healthy mites were ex-
posed to capilliconia only in the first 2 days of the observation period and
that no additional mortality related to the fungus was observed after the fifth
day (test 1 ). For some unknown reasons, the highest levels ofM.
non-germinating capilliconidia (23.6%) and without adherent capilliconidia
(40.9%) were observed in test 3.
was found to contain developing hyphal bodies
while only 15.3% of
contained those structures. Only 1% of the
mites of the latter species died during the observation period, but the deaths
G.J. DE MORAES AND I. DELALIBERA JR.
of a strain
to five mite
laboratory conditions. The starting
number of individuals in
Koch or T.
al. and 20
(Denmark & Muma) or
man & McGregor s.1,
Mite species Dead mites with hyphal bodies a Overall % % Non
1 2 3 4 5 6 7 8 HB GC NGC
0 0 14 77 77 78 78 78 79.5 19.4 0 1.1
0 0 0 0 0 0 0 0 0 39.0 18.4 42,6
0 0 0 0 0 0 1 1 15.3 62.7 1.1 20i8
Averages of tests 2 and 3
0 5.5 20,5 28.5 36.0 - - - 39.2 14.9 13.4 32.5
0 0 0 0 0 - - - 0 0 0 100.0
Averages of tests 4, 5 and 6
0 0 18.3 36.7 52.0 - - - 60.9 11.9 7.5 19.7
0 0 0 0 0 - - - 0 0 0.5 99.5
bHB =dead and live mites with hyphal bodies; GC=germinating capilliconidia; NGC= non-germi-
were probably due to other causes, considering the
low number ofhyphal bod-
in the mites. The
number of hyphal bodies in the live
overall proportions of 72.
minating capilliconidia of
but no hyphal bodies were 39,0 and
62.7%, respectively, while the overall proportions of
those respective species
with adherent but not germinating capilliconidia were 18,4 and 1.1%.
of those species without adherent capilliconidia were
20.8%, respectively. The average numbers ofcapilliconidia per
were 4.6 (0-41 ) and 3.1 (0-34), respectively. These results indi-
cate that the unsuitability of T.
and expecially T.
sp. is expressed largely after the acquisition of infective structures, and gen-
erally after the penetration of fungus in the hemocoel of the mites.
contained adherent capilliconidia or were infected by
despite the normal mobility of the mites in the rearing units. A single
s.1. (test 4) was found with three non-germinated capilliconidia
adherent to the legs. This corroborates the fact that not a single predator of
either species has ever been found infected by
sp. in periodical
samples taken over the last 2 years from areas where the fungus is commonly
The results of this study indicate that the unsuit-
ability of both phytoseiids as host
is expressed at the acquisition
phase of the infective structures.
SPECIFICITY OF NEOZYGITES TO MONONYCHELLUS
was described over 100 years ago (Witlaczil, 1885), but was
only recently revived, after
was split to include
Lipa, 1971; Remaudiere and Keller, 1980).
As mentioned by Lipa ( 1971 ), there was some resistance among experimen-
tal mycologists to accept these changes, and for this reason, it is possible that
some species reported in the literature after that time under
may in fact belong to
was put into the newly
described family Neozygitaceae (Ben Ze'ev et al., 1987).
Humber et al. ( 1981 ) mentioned previous reports of six species of ento-
mophthoralean fungi attacking mites, namely
(Tsintsadze and Varta-
(Weiser & Muma) and
also reported the collection of an unidentified species of
Baker and Pritchard in northeast Brazil. Van der Geest
( 1985 ) summarized the literature on infectious diseases of spider mites, many
of which were reported to be caused by the species of
by Humber et al. ( 1981 ) and other unidentified species of the same genus.
He reported several
Eutetranychus banksi (McGregor)
Ehara infected by those fungi.
Some species of
are known to infect insects, expecially Homop-
tera and Thysanoptera.
(Nowakowski) has been reported
on aphids and the green scale,
Coccus viridis (Green),
(Witlaczil, 1885; Car-
ner and Canerday, 1968; Keller and Wuest, 1983
), N. parvispora
al. has been observed on
Lind. (MacLeod et al., 1976; Keller
and Wuest, 1983) and
(Speare), on the mealybug
Matile-Ferrero (Le Ru et al., 1985 ). Other species of this genus are
also expected to infect those or other groups of organisms (see Keller and
Certainly, to satisfy the requirements for the introduction of the fungus
into Africa, further tests involving organisms found in the importing coun-
tries will have to be done. However, the results of this study indicate that the
tested may be rather specific, because it did not cause any
significant infection to two phytophagous mite species belonging to the same
the species from which the fungus was collected, nor to
the two most common predaceous mites on cassava plants in northeast Brazil.
This work was supported by the EMBRAPA/IITA agreement for biological
control of cassava pests.
G.J. DE MORAES AND I. DELALIBERA JR.
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