FOOD PREFERENCES OF LASIODERMA SERRICORNE (F.) (COLEOPTERA: ANOBIIDAE) ON FOUR TYPES OF TOBACCO

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1 Sarhad J. Agric. Vol.24, No.2, 2008 FOOD PREFERENCES OF LASIODERMA SERRICORNE (F.) (COLEOPTERA: ANOBIIDAE) ON FOUR TYPES OF TOBACCO Muhammad Saeed*, Said Mir Khan* and Muhammad Shahid** ABSTRACT Flue-cured Virginia (FCV), Sun-cured Rustica (SCR), Dark Air-cured (DAC) and Air-cured Burley (ACB) were evaluated for preference by the 4 th instar larvae and adult stages of Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae). Nicotine, reducing sugars and starch contents were determined and the impact of chemical factors on preference was worked out. FCV tobacco was preferred by both larval and adult stages with 2.18 and 1.49 beetles, respectively followed by SCR with 1.58 larvae and 1.25 adults. ACB was preferred by minimum number of larvae (0.64) and adults (0.82). Nicotine content was high (4.09%) in SCR, while low (1.42%) in DAC. Maximum reducing sugars (14.27%) and starch (6.89%) was recorded in FCV, while minimum (0.55%) reducing sugars and (1.14%) starch documented for ACB. Significant positive interaction among the larval and adult stages of L. serricorne with reducing sugars and starch revealed that FCV was highly preferred by larval and adult stages due to high contents of reducing sugars and starch, while ACB was least preferred due to low contents of reducing sugars and starch. Nicotine had non-significantly negative effect on the preference of both larvae and adults. Key words: Lasioderma serricorne, Preference, Tobacco Types, Feeding. INTRODUCTION Cigarette beetle, Lasioderma serricorne (Fabricius) (Coleoptera: Anobiidae) is a serious pest of stored tobacco (Gopalachari, 1984), and is known to infest and consume all stages of the product, resulting in spoilage of at least 1% (US$300 million) of stored tobacco stocks per annum (USDA, 1972). The pest occurs throughout the tropical and subtropical regions of the world. Although low temperature and humidity restrict its growth, yet it occurs commonly in warm buildings throughout the temperate regions (Arbogast et al., 2003). It breeds on a wide variety of commodities, including both plant and animal materials (LeCato, 1978; Ashworth, 1993), and is one of the several beetle pests that commonly infest warehouses and retail stores (Arbogast et al., 2000, 2002). Besides tobacco, also infests a wide range of other stored commodities such as grains, rice, beans, cotton seeds, dry yeast, chilli powder, ginger, turmeric, saffron, dates, raisins, dried figs, cereals, leather, cocoa, dried vegetables and even pyrethrum powder (Gopalachari, 1984; Ryan, 1995). The insect larvae that eat stored leaves and contaminate the product with excreta and body oils cause damage to tobacco. Infestation may occur on farm storage, tobacco shipments, in the warehouses, factories and at retail outlets (Ryan, 1995). L. serricorne attacks the principal types of cigarettes, cigars, chewing and snuff tobaccos. Burley tobaccos are rarely preferred (USDA, 1972). Principal cultivars of tobacco grown in Pakistan are Flue-cured Virginia (FCV), Sun-cured Rustica (SCR), Dark Air-cured (DAC), and Air-cured Burley (ACB). The type of tobacco influences the duration of the life cycle of beetles. In Flue-cured tobacco with low nicotine and high sugars, the beetle completes its life cycle earlier i.e., in 50 days, while in tobacco with high nicotine and very small amounts of total sugars and starch, the development is very slow and the beetle completes its life cycle in a range of 65 to 80 days. The type of tobacco also affects the oviposition. L. serricorne lays more eggs in fluecured tobacco than in other tobacco types (Joshi, 1968). When feeding on tobacco, L. serricorne survives best on high sugar/low nicotine tobacco. It can survive on tobacco having up to 4% nicotine. The larvae do not survive on a tobacco diet containing 8.25% nicotine (Ryan, 1995). A successful integrated pest management (IPM) Program cannot be implemented without knowing the feeding preferences of L. serricorne. Therefore, the objectives of this study were to determine the beetle preference and to explore its association with the chemical profile of tobacco types. MATERIALS AND METHODS This study was conducted in Lakson Tobacco Company Limited Mardan, NWFP, Pakistan during year The experiments were laid out in a randomized complete block design (RCBD) with six replications. Four types of cured tobacco viz., Flue-cured Virginia (FCV), Sun-cured Rustica (SCR), Dark Air-cured (DAC) and Air-cured Burley (ACB) were tested for preference/non-preference by the 4 th instar larvae and adult stages of L. serricorne during October, Cured leaves weighing 150 g of each test plant was * Faculty of Agriculture, Gomal University, Dera Ismail Khan, NWFP Pakistan. ** NWFP Agricultural University Peshawar Pakistan.

2 Muhammad Saeed, et al. Food preferences of Lasioderma serricorne (F.) (coleoptera: anobidae) 280 cleaned by conditioning (Steam) followed by Sandreeling to remove dust. A paper sheet was spread on the floor of experimental chamber (Fig.1) measuring 45cm x 40cm x 40cm and divided into four equal sections with a 5 cm circle in center of the paper in such a way that an equal space among host plants was maintained. The clean tobacco was cut into small pieces, and 10 g of each test leaves was kept on the four sections of paper in rearing chamber. Populations of L. serricorne were collected from the tobacco warehouses located in Swabi area of NWFP, Pakistan during May-June, The colonies were reared on wheat flour: yeast extract (20:1) and maintained at 28±2 C and 65-70% R.H. as outlined by Ryan (1995). Colonies maintained by regular transfer of emerging adults into fresh jars having flour diet. Six female adults and larvae of L. serricorne obtained from the insect colonies were separately placed in center of the circle in different experiments with the objective to give them free choice of selection and feeding for twelve hours. Females are attracted to tobacco (Kohno et al, 1983) and lay more eggs on flu-cured tobacco (Kurup, 1961). No insecticidal measures were taken during the whole experimental period. Biochemical Assays The biochemical profile of host tobacco was worked out during October, 2004 in the Quality Assurance Laboratory, Lakson Tobacco Company Limited Mardan, Pakistan. Cured leaf samples of different tobacco types each of 200 g weight were cleaned by conditioning (Steam), Sand-reeled to remove dust, ground, passed through 1mm mesh and stored in dry polythene bags at 12 to13 % moisture content. Reducing sugars and nicotine were determined by BURKARD SCIENTIFIC SFA-2000 Method Sheet (CORESTA recommended Methods) while starch was determined by Spectrophotometer. Statistical Analyses Analysis of Variance (ANOVA) was performed for the tobacco types preferred by the larval and adult stages of L. serricorne using SAS inst. (1996). The impact of chemical factors on preference/non preference by L. serricorne was worked out through simple correlation. Means were separated by Least Significant Difference (LSD) Test (Steel and Torrie, 1980). RESULTS AND DISCUSSION Tobacco type preference Significant differences were observed in the rate of preference by larval and adult stages of L. serricorne (Table I). FCV tobacco was significantly preferred the most by both larval and adult stages with 2.18 and 1.49 numbers, respectively. ACB was significantly the least preferred type with minimum number of both larvae (0.64) and adults (0.82) of L. serricorne. SCR and DAC were preferred by statistically similar number of adults i.e., 1.25 and 1.15, respectively. These findings are in agreement with research findings of Akehurst (1981) who reported that all tobaccos could be infested, lower preference given to ACB and Maryland tobacco. Ryan (1995) reported that females of L. serricorne lay more eggs on FCV than other tobacco types and larvae are unable to survive on tobacco diet containing high contents of nicotine (8.25%). Bharati et al. (2001) reported highest net reproductive rate (6.502) of L. serricorne on FCV followed by ACB (5.396). The population took and days to double itself on FCV and ACB, respectively. Rao et al. (2002) reported FCV tobacco to be highly susceptible while ACB and other tobacco types were the least preferred by L. serricorne. Figures 2 and 3 further elaborated the association of larvae and adults with reducing sugars and starch in four tobacco types. The relationship is direct curvilinear as the increase in reducing sugars and starch had encouraged the population of L. serricorne. Though nicotine content was statistically different in tobacco types (Table II) yet it had a nonsignificant relationship with preference of larvae and adults (Table III). Figures 2 and 3 showed that nicotine content had a non-significant irregular relationship. Kohno et al. (1983) reported that attractiveness of the tobacco leaves changes with change in chemical composition and concluded that active components for preference were volatile essential oils. Levinson & Levinson (1987) and Dowd (1989) stated that L. serricorne could tolerate nicotine content to some extents. Ryan (1995) also reported that L. serricorne survives best on high sugar/low nicotine tobacco, so Flue-cured is at most risk. Carvalho (1995) reported that larva of L. serricorne grew better on tobaccos with high sugar contents and its development was slower at high nicotine contents. She observed the highest rate of mortality on Burley (flavor) (78%) and lowest rate on both Virginia (filler) and Burley (filler) (44%). Bharati et al. (2001) concluded a combine inverse effect of reducing sugars and nicotine contents of tobacco on the life parameters of L. serricorne. Hence, we concluded that Flue-cured Virginia was more favored by L. serricorne compared to Suncured Rustica, Dark Air-cured and Air-cured Burley tobaccos and appearing relatively more susceptible. Tobacco types with high concentrations of reducing sugars and starch showed stronger association with

3 Sarhad J. Agric. Vol.24, No.2, the larvae and adult populations of L. serricorne. Tobacco types with high content of nicotine were negatively correlated with the preference by larvae and adults of L. serricorne. ACKNOWLEDGEMENTS The authors express their gratitude to the owners, managers and staff of Lakson Tobacco Company Limited for their assistance. Many thanks to Richard Terry Arbogast of USDA-ARS Center for Medical, Agricultural and Veterinary Entomology for his suggestions, critical review, and provision of related research material. Thanks to Dr. Fida Muhammad & Dr. Iftikhar Husain Khalil, Dept. of Plant breeding and Genetics, NWFP Agri. University, Peshawar for helpful guidance during the data analysis. Many thanks to Maria Otilia Carvalho, Bill Lingren and Dr. S. Ch. Papadopoulou for providing research papers, materials and reading the manuscript. Table I Mean comparison of the data regarding preference by 4 th instar larvae & adult stages of L. serricorne in four tobacco types offered as food. Tobacco type Preference (numbers) Larvae Adults Flue-cured Virginia 2.18a 1.49a Sun-cured Rustica 1.58b 1.25b Dark Air-cured 0.87c 1.15b Air-cured Burley 0.64d 0.82c LSD (0.05) Means with the same letter within the column are not significantly different at 5% probability level. Chemical composition of four tobacco types in Table II indicated that FCV had high percentages of reducing sugars (14.27) and starch (6.89), while ACB had minimum reducing sugars (0.55%) and starch (1.14%) contents. Table II Nicotine, Reducing Sugars & Starch content of four tobacco types. Tobacco Type Nicotine Reducing Sugars Starch % Flue-cured Virginia 1.98c 14.27a 6.89a Sun-cured Rustica 4.09a 4.16b 6.56a Dark Air-cured 1.42d 0.85c 2.19b Air-cured Burley 3.25b 0.55c 1.14c LSD (0.05) Means following by different letters within the same column are significantly different from each other at 5% probability level. Regression analyses revealed a positive relationship of larvae and adults with reducing sugars and starch contents (Table III). Table III Coefficients of larvae and adult stages of L. serricorne with chemical constituents of four tobacco types. Stage interaction with Nicotine Reducing Sugars Starch Larvae ns * * Adult ns * * ns: Non-significant * Significant at P < 0.05 (both 1% & 5% have the same results).

4 Muhammad Saeed, et al. Food preferences of Lasioderma serricorne (F.) (coleoptera: anobidae) 282 c b e d a Fig. 1: Experimental chamber for L. serricorne (a) Flue-cured Virginia (b) Sun-cured Rustica (c) Dark Air-cured (d) Air-cured Burley (e) L. serricorne release Point Larva 14 No. of larvae L. serricorne Nicotine % RS % Starch % Chemical Constituents(%) 0 ACB DAC SCR FCV 0 T obacco T ype Fig. 2: Relationship of larval population with nicotine, reducing sugars (RS) and starch content in Flue-cured Virginia (FCV), Sun-cured Rustica (SCR), Dark Air-cured (DAC) and Air-cured Burley (ACB) tobacco types. Fig. 3: Relationship of adult s population with nicotine, reducing sugars (RS) and starch content in Flue-cured Virginia (FCV), Sun-cured Rustica (SCR), Dark Air-cured (DAC) and Air-cured Burley (ACB) tobacco types.

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6 Muhammad Saeed, et al. Food preferences of Lasioderma serricorne (F.) (coleoptera: anobidae) 284