In vitro repellency evaluation of selected botanical extracts against cigarette beetle , Lasioderma serricorne

To investigate the percent repellent outcomes of the chosen botanical extracts against adults cigarette beetle (Lasioderma serricorne Anobiidae: Coleoptera) an experiment was carried out at the Entomology Section, Department of Agricultural Sciences, University of Haripur, in 2015. Two native botanical extractions obtained from Mentha longifolia (Mint) Lamiaceae and Momordica charantia (Bitter Gourd) Cucurbitaceae were tested for finding the repellent outcomes against Lasioderma serricorne while exposing them for ten days. The concentrations of botanical materials were 25, 50 and 75%. Each treatment was replicated three times with completely randomized design (CRD). Outcomes confirmed that highest repellency was observed at tenth day of exposure by M. longifolia i.e. 86.667% at 75% concentration versus L. serricorne, followed by M. charantia at the same dose (75%) where the percent repellency was 76.67. The experiment further confirmed that as the exposure time and the concentrations increased the percent repellent outcomes of the L. serricorne also increased.


Introduction
Tobacco is mainly cultivated in Khyber Pakhtunkhwa (KP) Pakistan.The main growing areas include viz., Buner, Charsadda, Swabi, Swat, Mardan and Manshera.Nicotiana tabacum L and N. rustica L are the main species which are cultivated in these areas [1].At national level it attributes Rs. 34 billion to GDP along foreign earning of Rs. 587 million by the cigarette manufactures.It generates six times more excise duty than cotton yarn [2].Globally, stored product pests cause significant losses to storage commodities.In Pakistan, these losses are varied from 10 to 25% [3,4].The cigarette beetle, Lasioderma serricorne is a serious pest of stored products and causes considerable losses and has been regularly reported in most of the tropical and sub-tropical regions while feeding on all types of tobaccos like flue cured, rustica, burley and oriental tobaccos [5].Similarly, the preferred way of controlling L. serricorne is by using insecticides.Pyrethroids are used for crawling and flying populations while Aluminum phosphide is used against all stages in the form of fumigants.But the research showed that consistent uses of synthetic insecticides are causing negative effects on the environment and also on nontargeted organisms.Similarly, insecticides create problems of resistance in the target pests.[6].So it is necessary to find safe crop protecting agents for their control [7,8].Some plant extracts have been reported with numerous negative effects on insects [7, 9, 10].Botanical extracts are highly selective, simple to decompose, offer no residual effects, and trigger no contamination or risks to man and environment [11,12].In previous studies, the bioactivities of a large number of botanical oils have been also assessed verses number of insects found in stores [13,14].Based on the significance of plant extracts nature, this research was conducted to check the efficacy of various plant materials viz., Momordica charantia and Mentha longifolia against L. serricorne adults to investigate the percent repellent effects of chosen botanical extracts against L. serricorne adults in laboratory settings and to find out the effects of different concentrations of the chosen botanical extracts at different times of exposure.

Materials and methods
The experiment was carried out at the Department of Agricultural Sciences Entomology section, University of Haripur during 2015 to investigate the percent repellent outcomes of the chosen botanical extracts versus adult Lasioderma serricorne.

Test materials
Botanical materials utilized in the experiment were Mentha longifolia (T1) and Momordica charantia (T2).The above botanical materials were purchased from local market in District Haripur and then rinsed followed by drying at controlled temperature and relative humidity i.e., 27±2 • C & 75 ± 5%.Plant materials were extracted via the acetone solvent for extraction (100g of each sample in 75 ml of ethyl alcohol).The extracts were properly dried and stored in sealed glass vials in refrigerator.These botanical extracts then assessed for their repellency versus the adults of L. serricorne to determine the effective plant extract, percent concentration and exposure period.

Rearing and maintenance of insects culture
The checked insects were taken from laboratory cultures kept in incubators at 30±2 • C & 73+5 % relative humidity (RH).Wheat flour with Baker's yeasts (20:2 w/w) was the food source for insects at 12-12.5% humidity.Collection of eggs was done by keeping the adults on filter papers for 45 hours.When eggs were hatched, then the larvae were shifted to other cages for maturity.Seven days older beetles were taken in petri dishes (10 adults per petri dish) and the botanical extracts were applied on them for finding their repellency.Poly tetrafluoreo ethylene (Fluoen) coating was done to avoid escaping of insects from the petri dishes.Repellency From the stock solution, various concentrations (25, 50 & 75%) of each plant extract were prepared by using acetone as a diluting solvent.The concentrations of test materials were obtained by taking 25, 50 and 75ml of each extract in 100ml of acetone to make 100 percent solution.The test solution was applied to each half of a filter paper disk.The control half was treated with acetone only.Filter papers were allowed to dry in open air for 10 minutes to evaporate the acetone.The diluted concentrations were used for subsequent experiments.Thirty mature beetles (seven days older) were released at the center of petri dish.In order to avoid the death of insects due to unavailability of food, a small quantity of diet was kept at the either side of the petri dishes.Percentage repellency was determined by calculating the numbers of adults in treated & untreated areas repeatedly over the period of ten days.Each treatment was replicated thrice.Percentage repellency (PR) values were found out via the approach showed by

Data analyses
The experiment was laid out in completely randomized design (CR, design) with four replications.Collected data were statistically analyzed using computer statistix ® 8.1 software.The least significant difference (LSD) at 5% level of significance was exploited to compare the treatments means [16].

Results and discussion
Percent repellency at 1 st day of exposure Lasioderma serricorne was exposed to botanical extracts viz.Mentha longifolia and Momordica charantia to the concentrations of 25%, 50% and 75% and 0% (control) so to find out their repellent outcomes.Amongst the tested botanical extracts M. longifolia showed repellent results of 26.67% at the concentration of 25% (Table 1) after 24 hours (1day) while M. charantia showed 20% (Table 2) repellent results.The percent repellent results observed on 50% concentration were 33.33 by M. longifolia and 30 by M. charantia as shown in (Table 1 & 2).At 75% concentration M. longifolia proved repellency of 56.67% which was similar with the findings of [17] who found that M. longifolia is most effective versus pests in stores at 75% concentration while M. charantia gave 46.67% repellent values respectively.The data further indicates that at control (0%) no repellency had been observed.

Percent repellency at 2 nd day of exposure
At the second day of exposure M. longifolia triggered percent repellent value of 30 % at 25% concentration while M. charantia showed repellent value of 23% at the same concentration.At 50% concentration M. longifolia caused repellency of 36.67% and M.
Charantia caused 33.33%.At the concentration of 75% repellency of 60% had been provided by M. longifolia while M. charantia showed 50% as shown in (  1, 2) and these results are accordance with the findings of [18] who observed that M. charantiea provided repellent outcomes of more than 60%.At control (0%) no repellency was observed.Percent repellency at 9 th day of exposure Percent repellent effects of the tested plant extracts on L. serricorne after exposure period of two hundred sixteen hours (9 days) showed that at control (0%) no repellent outcomes were observed.M. longifolia caused repellent value of 53.33% at 25% concentration followed by M. charantia which caused repellency of 46%.At 50% concentration M. longifolia showed repellency of 60% while M. Charantia caused 56.67%repellency.When the concentration was applied @ 75%, repellency of M. longifolia was 83.33% whilst M. charantia showed73.33%repellency (Table 1 & 2).These results are in accordance with the outcomes of [10] they find out high repellency of M. longifolia versus insects in stores.Percent repellency at 10 th day of exposure Percent repellent outcomes of the tested botanical extracts against L. serricorne for exposure period of two hundred forty hours (10 days) showed that at control (0%) no repellency had been observed.M. longifolia gave repellent value of 56.67% at 25% concentration while M. charantia caused 50% repellency.At 50% concentration M. longifolia showed repellency of 63.33% while by M. charantia caused 60% repellency.At the concentration of 75% repellency of 86.67 % was provided by M. longifolia and M. charantia caused 76.67% repellency (Table 1 & 2) and these results strongly matched with the results [18] they declared that M. longifolia has the significant ability to repel L. serricorne and S. oryzae at low concentration.Likewise, M. charantia proved to be high efficient botanical extract versus L. serricorne after M. longifolia.

Table 1 &
2) At the concentration of 75% repellency of 70% proved by M. longifolia while M. charantia gave 60% repellency.These results are in close accordance with the results of [20] who found the above botanical extracts effective versus pests in stores in the tested concentrations.Percent