Food preference, repellent and attractive effects of 14-kinds of spices to khapra beetle Trogoderma granariun Everts (Coleoptera; Dermestidae)

This study aim to determine the food and oviposition preference for khapra beetle, Trogoderma granarium Everts, using different types of spices, also the attractive and repellent effects of the spices to the adults and larvae of the beetle.Results indicated that adults and larvae preferred cinnamon spice than the other, with a highest percent of 15.33 and 34.66%,respectively, when given a free choice for feeding. On the other hand adult beetle preferred cinnamon than other spices for eggs laying which gave the highest mean number (22.66) during its lifespan. Cinnamon showed the highest attractive effect to adult while red pepper showed the highest repellent effect .


Introduction
Although spices have been used since ancient times, they are playing anew and important role in modern foods preparation; they not only add unique flavor to our foods but contribute color and variety as well. Many of these substances are also used for other purposes,such as medicine, religious rituals, cosmetics, perfumery or eating as vegetable (1,2). Spices are subject to infestation by stored product insects especially during the hot period of the summer(3).
The great spectrum of damages to stored products including spices are caused by khapra beetle Trogoderma granarium Everts. Iraq is one of the countries considered to contain endemic population of khapra beetle (3,4). It is very destructive and economically important species. It is prevalent relative to other species of stored grain pests, may also be related to its greater tolerance to prolonged high temperature, can tolerate colder climates (5) and its generally greater resistance to control measure (6,7,8).
This study was conducted to determine the food and oviposition preference , repellent and attractive effects of fourteen kinds of spices to the adults and larvae of khapra beetle. Food preference of larvae to the spices Similar experiments as indicated later were conducted but in this case 100 specimens of 4th instar larvae (after one day starvation) were released in the tray center instead of adult beetles.

Egg laying preference of adults to the spices
The same experiment of the adults preference to the spices for feeding was used for preference of egg A completely randomized design was used and the data were subject to analysis of variance (ANOVA) and mean values were compared by Duncan's multiple range test to determine the significant difference between varieties (12).

Results and discussion Food preference of adults to the spices
Results (table 1) revealed that adults prefer some spices than another. The highest percentage number 15.33% were attracted to the cinnamon spices while the percentage number of adult attracted to the rested spices was less than that with differences between spices. The statistical analysis showed no significant differences between cardamon, coriander, cubeb, ginger, roselle and anise. On the other hand thyme and clove showed lowest preferable by the adult, the percentage of adult presented on there was 3 %.
These results are in agreement with (13), whose they estimated the olfactory response of Lasioderma serricorne (Fab.) and Stegobium paniceum L. to 27 different spices and found that turmeric gave the highest percentage of attraction to the adult followed by black pepper, cinnamon and ginger. The chemical component of spices may be play an important role in the adult choice for the spices and preference.

Food preference of larvae to the spices
Results in table (2) indicated that the percentage number of larvae found in the different types of spices when given a free choice for feeding, various greatly due to the type of spices. It was highly percentage (34.66%) on cinnamon type; followed by: ginger 13.66% and roselle 10.66%. However, the larvae displayed low preference degree to the all other spices and the value of preference ranged between 0.33 on cardamom and black pepper to 7.66% on Bay leaf. The chemical components of the food host (phenols and asters) play an important role in the insect food preference to the hosts (14).
Also the physical properties of the spices, especially the hardness have a greet effect in the color, shape, touch larval preference of the spices. Egg laying preference of adults to the spices Table (3) indicated the number of eggs laid by female of khapra beetle on the different types of spices when giving a free choice. It was found differences between the spices in the number of eggs laid. The female laid the highest number of eggs on the cinnamon spice which was 22.66 eggs, while laid the lowest number of eggs on the cubeb spices which was 2.00 eggs. The other spices ordered at the following succession cumin, ginger, cardamon, Roselle, anise, thyme, bay leaf, mint, clove, black pepper, red pepper and coriander. The statistical analysis of the data showed a significant difference in the number of eggs laid between cinnamon and the all other spices while showed no significant differences between them. The statistical analysis showed positive significant correlation between food preference of larvae and adults and the adult preference to lay their eggs on the spices. (15) mentioned that the preference to lay eggs by stored product pests depending, with no doubt, to the physical and chemical nature of the food attacked.

Attractive and repellent effects of spices used to adults and larvae
Results in table (4) indicated that cardamom, coriander, cumin, ginger, anise, mint, clove and bay leaf showed attractive effect by adults while red pepper, black pepper, cubeb, cinnamon and thyme showed repellent effect. The results showed that cumin was the more preferable spice for the adults than the others which gave the highest attraction percentage of 22.66% whereas black pepper and cubeb have the lowest attraction percentage 3.00%. On the other hand, red pepper have the highest repellent percentage 14.00% whereas candamon have the lowest repellent percentage 4%. (16) indicated that cinnamon works as an effective insect repellent. Also (17) mentioned that thyme, Thymus serpyllum is used as mild insect repellent.
Results in table (5) revealed that all spices showed an attractive property to the larvae with the exception of cinnamon, mint and clove which appeared repellent effect to its. Red pepper showed the highest attraction percentage 17.66% while ginger and clove showed the lowest attraction percentage 4.00%. The variation found in the attraction and repellent percentage may be attributed to the variation in chemical components of these spices. The spices may influence in the insect refraction able behavior therefore it may be act as active deterrents or food stimulants and some times the insect attractive to the unfavorable substance because the effective substance within the food composition may be not comprehend by the insect due to its vapor concentration which may be not sufficient and effective to the olfactory response of the insect.

Conclusion
1. Khapra beetle prefers the cinnamon than other spices for feeding and egg laying when given free choice. 2. Adult khapra beetle showed more chemotropism to cumin than other spices while larvae showed more chemotropism to the red pepper. 3. The variation found in the attraction and repellent percentage may be attributed to the variation in chemical components of the spices.