Some observations on natural enemies of poplar borers in Pakistan
Some observations on natural enemies of poplar borers in Pakistan
Hanif Gul and M. Ismail Chaudhry
ABSTRACT
Three Braconids and one Eulophid parasitizing poplar
bark borer, Indarbela quadrinotata (Pseuderbelidae,
Lepidopteral) larvae and pupae, were recorded.
Aeolesthes sarta (Cerambycidae, Coleoptera) grubs were
found predated by a mite predator. Entomophathogenic
fungus attacking all stages of I. quadrinotata and
Elaterid predator of A. sarta, pit borer Apriona cinerea
(Lamiidae, Coleoptera) were recorded. Observations on
the biology of Elaterid predator of A. sarta and A.
cinerea in the laboratory showed that a predator larvae
consumed 2 host grubs of 1-2 months age in 4 days. ON an
average single predatory larvae killed 61 and consumed
24 host grubs in 14 months of its predatory larval life.
Due to predation by mites on A. cinerea a mortality of
8-18% was recorded. Predation of formicids on larvae of
I. quadrinotata was studied at Islamabad and 8 to 35%
larval galleries were observed to contain formacids. The
maximum predation occurred in the month of December.
Natural enemies comprising of predators and macro and
micro parasites have a considerable importance as
bio-control agents for combating pests. They are most
effective in suppressing the pest populations and are
the safest instruments for dealing with pest invasions.
Bacilus thruingiensis a disease causing bacterium
extracted from various lepidopterous pests, has been
developed into commercial microbial insecticides. Many
worker such as Smirnoff (1963), Sider, (1965), Mihalache
et al. (1972), Podgwaite and Cambell (1972), Jaque
(1972), Yendal et al. (1973) and Arru (1975) tried
Bacilus thuringiensis in the form of Thuricide,
Entobacterin, Dendrobacillus and Dipel against different
forest defoliators with good results. Smirnoff et al.
(1972) tried B. thuringiensis scale in 1972 and as
aerial spray on large scale in 1974 with considerable
success. Mihalache et al. (1972) found Dipel very
effective against Lymantria dispar, Malacosma anectri
and Teritix viridama. Insect Pathogenic bacterium B.
poplillae developed to control successfully infestation
of Japanese beetles in U.S.A. in 1942. The bacterium B.
thuringiensis on a wide range of Lepidopterous
caterpillars formed basis for development of commercial
insecticides. The potential use of nematodes as natural
regulators of insect populations has been discussed by
Glasser and Wilcox as early as 1918. Zwalurvenburg
(1928) and La Rivers (1949) presented early lists of
nematodes insect associations. Theodorides (1950) cited
over 100 species and sub-species of nematode associated
with insects in France. Ruhm (1956) listed a similar
number of nematodes associated with Scolytide in
Germany. Masey (1960) recorded several nematodes
parasites considerably reducing reproductive potential
of bark beetles by causing sterility and in some cases
killing the host. Coutruier (1963) described two species
of mermithids parasitic in common chafer, Melolontha
melolontha. Artyukhovskii (1955) described nematode
association with forest Lepidoptera in Voronezhskoblest.
Poplars are among the fast growing species introduced for
high wood yield but unfortunately they are subjected to
the attack of defoliators and borers. The control of
defoliators is easily possible with the use of chemical
insecticides but the borers being concealed feeders pose
a great threat to poplar culture. Studies on natural
enemies of different borers were carried out with a view
to control poplar borers safely and economically as no
work on the bio-control of poplar borers and their
natural enemies has been carried out in Pakistan.
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December 1992
Vol. 42, Iss. 4
