Management two years (from April to November

Management of bark beetles

Natural enemies

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 Studies on important natural enemies associated
with bark beetles were followed as per the standard methods adopted by Dahlsten
and Stephen (1974) and Narendran et al. (2001) with little adjustments.

Hymenopteran
parasitoids

For recording the seasonal incidence of hymenopteran parasitoids associated
with bark beetles viz., I. stebbingi, P. major and P. scitus
experiments were conducted during 2015–2016
in Nowpora village (33°61.078′ N,
075°18.700′ E, elevation 5920 ft.) in Anantnag District, Jammu &
Kashmir. The samples
were collected for a period of two years (from April to November 2015 and from April to November
2016). After every month ten branches (1–8 cm in diameter, 20–50 cm in length) by
careful observation were cut from host trees (P. wallichiana) naturally infested with bark beetles. The sample branches were brought to the
laboratory and kept in rearing boxes made up of glass fitted with white muslin
cloth for the possible emergence of parasitoids(Figures
2–4).. After every
ten days emerged parasitoids from infested
branches were counted and some branches were also debarked to examine the
activities of parasitoid stages associated with bark beetles. The same procedure was followed throughout
the year and the parasitoids collected were listed and the
proportion of a particular species out of the total (i.e., dominance
coefficient) was determined. The coefficient of dominance of a parasitoid
species was calculated as follows:   

                                                           Number of a
particular species

 Dominance
coefficient (%) =                                                                  x
100

                                                        Total number of predators collected

During year 2016, the same sampling procedure was followed
and the dominance coefficient
(%) was determined as per the above formula.  

Predators  

For
recording the seasonal occurrence of predators associated with bark beetles viz.,
I. stebbingi, P. major and P. scitus, experiments were conducted in the same
aforementioned study area. The samples were collected for a period of two
years (from April to
November 2015 and from April to November 2016) with the interval of 15 days between the successive
sampling instances. Since three aforementioned bark beetle species occupy
different parts of the host tree, three wooden frames (sampling units) were
made available, one for each species. The dimensions of the wooden frames were
0.06 m2, 0.10 m2 and 0.16 m2 for P. scitus, P. major and I. stebbingi respectively.
After every
fifteen days, a total of thirty samples were taken (ten from each species) from
severely infested logs, first by marking the bark surface by using wooden
frames, then by carefully debarking the sample area occupied by each species
(Figs. 3–4). Data of each predator species with its
associated host beetle stage were recorded. The
same procedure was followed throughout the year and the predators collected
were listed and the proportion of a particular species out of the total
(i.e., dominance coefficient) was determined as per the aforementioned formula
used for parasitoids for both years.

 Fungal control
against bark beetles

Studies
on use of entomopathogenic fungi against bark beetles was followed as per the
earlier standard methods adopted by Batta (2007) and Jakus and Blanzee (2011)

Pinus wallichiana branches used in the experiments

Naturally
infested branches of P. wallichiana were collected during
2017(April to November
2017)   from a severely infested pine stand located in
Nowpora village (33°61.078′ N, 075°18.700′ E, elevation
5920 ft.) in Anantnag District, Jammu & Kashmir (Figure 1) and forest check
point, Tangmarg (340 03.797′ N, 074024.948′ E, Elevation 7552 feet) in Baramulla
District, Jammu & Kashmir (Figures 1­­­­–3).  The infested branches were selected after
observing bark beetle infestations (Figure 4–5). The sample branches were transported
to the Animal House, Department of Zoology, University of Kashmir in plastic
boxes for the evaluation of fungal
treatments against I. stebbingi.

Fungal species used in the treatment  

The
commercial bioprepration of three entomopathogenic fungi viz.,
B. bassiana, M. anisopliae
and L. lecanii
were obtained from Green
Life Biotech Laboratory, Somanur, Coimbatore, India. Experiment was performed
from April to November 2017. A total of 90 branches naturally infested with bark beetles, categorized into five groups (G1–G5),
were used in the experiment for each bark beetle species. Each replicate
represented three infested branches and six replicates per experimental
treatment were used for each bark beetle species (Table 1). The
used insecticide was cyclone (active ingredient: Chlorpyriphos 50% +
Cypermethrin 5%).   

The
fungal preparation was diluted in water: 1ml biopreparation/1000 ml water with
four drops of a common detergent as a wetting agent. Each fungal suspension
contained 1.0 × 109 spores of fungi in 1 ml. The fungal suspensions
were applied with a hand sprayer at 500 ml per log (Table 1). High volumes of
fungal suspensions were used for effective treatment so that suspensions would
penetrate spontaneously after application. After 10 days nine branches from
three treated replicates in each group were carefully debarked and the
percentage mortality of each bark
beetle species
were calculated and compared (Table 1). The same procedure
was applied for calculating percentage mortality of each bark beetle species after 20 days of
treatment.  

Fungal treatment of bark beetle adults (Petri plate assay)  

In
this method a total of 15 petri dishes containing filter papers were used;
three replicates were maintained for each treatment. The treatments were
performed by applying two rapid jetting sprays standardized at 1.0 ml per
replicate using a small calibrated hand sprayer (1 liter capacity) equipped
with a nozzle suited to low-volume spray application (Batta, 2007). In each
petri dish 40 adults of each bark
beetle species
were introduced before spraying. The same spray volumes (1
ml per replicate) were applied in the other treatments (Table 2). The mortality
percentage from each treated group was evaluated after 2, 4 and 6 days after
treatment. This mortality was shown either by the lack of movement of treated
adults within five minute period of continuous observation or by the appearance
of mycelial growth on the bodies of dead adults. The beetles were then
incubated in petri dishes under humid conditions for one week to promote
mycelial growth with the conidia and the conidiophores on their bodies.

Photography

Photographs during the field study
were taken by using Canon PowerShot SX60 camera fitted with
macro lens (Raynox MSN-505,
37mm). Analysis of digital images was done by using ImageJ analysis software
(Version 2006. 02.01). For morphometric description of collected predators images
were taken from haplotype with a Leica DFC295 camera attached to a
Leica M205A Stereozoom binocular microscope. Multiple images with different
focal levels were combined into a single image using Leica Automontage Software
(V4.10). Measurements were also taken from the type specimens with Leica
Automontage Software. All the specimens are deposited in the Museum, Department
of Zoology, University of Kashmir, Srinagar.  

Statistical analysis

The data obtained during
the present study were tabulated and graphically presented as per the required
statistical methods. Arithmetic mean, Variance, Range, Standard Error and SD
(Standard deviation) were used to analyze the data. The correlation between
maternal galleries and fecundity of females was   analyzed by Karl Pearson’s correlation
method. Head capsule width of different larval instars was used to calculate
total larval instars by Dyar’s ratio (Dyar, 1890). Statistical analysis was
done by using SPSS (Version 10.00).   

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Table 1. Treatments used against naturally infested branches of P. wallichiana with each bark beetle species under laboratory conditions.

S. No.

*Groups

No.of branches in each group/replicate

 Treatments

Quantity     (ml/log)

1

G1

18/6

B. bassiana

500

2

G2

18/6

M.
anisopliae

500

3

G3

18/6

L.
lecanii

500

4

G4

18/6

Insecticide

500

5

G5

18/6

Distilled water

500

*Each
group represents 18 infested branches with six replicates per experimental
treatment. Each replica contains three infested branches treated with five
treatments.

Table 2. Treatments used against each
bark beetle species using petri plate
assay under laboratory conditions.

S. No.

*Groups

No. of Petri dishes in each group/beetles

 Treatments

Quantity
(ml/Petri dish)

1

G1

3/120

B. bassiana

1.0

2

G2

3/120

M.
anisopliae

1.0

3

G3

3/120

L.
lecanii

1.0

4

G4

3/120

Insecticide

1.0

5

G5

3/120

Distilled
water

1.0

*Each group represents three petri dishes with 40 adult
beetles of P. scitus treated with
five treatments.

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