Effects of some abiotic factors on the exit of poppy root weevils (Ethelcus denticulatus Schrank) (Coleoptera: Curculionidae) from overwintering area

It is known that the production of poppy plants has been made since ancient times. There is evidence of the existence of poppy from the language of the Sumerians 5 thousand years ago. Poppy, Papaver somniferum L., is an annual plant native from Southeastern Europe to western Asia. Its species is cultivated extensively in many countries, including some European, Asian and Central and South American countries. The opium poppy is currently still an important agricultural crop grown for purposes of the food industry in the Turkey (Ýncekara 1972; Alavi, 1974, Anonymous, 2013). Poppy is allowed to grow all of the Afyon, Burdur, Denizli, Isparta, Kütahya, Tokat, Uşak and some districts of Konya province planted since 1974 (Alavi, A.,1974; Atakiþi, 1999).
        
Poppy seeds contain between 45-54% oil. Poppy seeds are used as a condiment with baked goods and pastries for their nutty odor and flavor. Poppy oil is widely used as edible cooking oil. The oil is also used in the manufacture of paints, varnishes and soaps. The poppy has had a tremendous impact on several societies as an opiate (Atakiþi, 1999; Anonymous, 2013). With the removal of the oil from the seeds, the remaining bagasse has a special importance. pulp of poppy contains about 36% crude protein and about 12% crude oil. These values are particularly important in the feeding of dairy animals. The rate of fat is increased in the milk of dairy animals fed with poppy pulp.
        
Poppy are one of the most important medicinal plants. Without a doubt, poppy is the most important drug plant in human history. Because opium and its derivatives could not be substituted in medicine and their synthetics could not be made. Opium is used in the production of morphine, codeine, other alkaloids and deodorized forms of opium. Morphine is the raw material from which heroin is obtained. Poppy plants are important as ornamental plants in flower gardens (Giray, 1985). 
        
Traditionally, the dry opium was considered an astringent, antispasmodic, aphrodisiac, diaphoretic, expectorant, hypnotic, narcotic and sedative. Poppy has been used against toothaches and coughs. The ability of opium from poppy to serve as an analgesic is well known. Opium and derivatives of opium are used in the pharmaceutical industry as narcotic analgesics, hypnotics, and sedatives. These compounds are also used as antidiarrheals, antispasmodics and antitussives. Opium and the drugs derived from opium are addictive and can have toxicological effects (Alavi, 1974; Incekara and Ones 1990;  Atakiþi, 1999).
    
With the increasing area where the poppy is grown, the problem of pests becomes more important. With this study, it is aimed to determine effects of some abiotic factors on exit of poppy root weevils (C. denticulatus) overwintering area.

Experiments were conducted in a farmer’s poppy fields located in Hacýkadem village (380 32’ K 290 31’ D) of the city of Uşak in 2014 and 2015. HOBO device has been installed in this poppy field to determine the average soil temperature (5 cm depth), average air temperature, average soil moisture, average air humidity and precipitation. The soil temperature, air temperature, soil moisture, air humidity and precipitation values were started to be taken before the poppy rootworm emerged from the overwintering areas. These values were taken until the second third of April when overwintering area was destroyed by poppy rootworm by 70-80%.
        
The poppy rootworm counts were made in two ways. In the first, yellow traps were used to determine the count of the pest. For this, in the third week of March, ten yellow water traps (plastic boxes (120 × 100 × 60 mm) were diagonally placed in poppy field (D. Bečka et al., 2010). There was a distance of 20 meters between each other. The other method used to determine the poppy root weevil was to check, the 4 different points of the field in one m2 through visual control method. The number of poppy root weevil was calculated on the basis of the numbers calculatedin the yellow water pitfall trap and through the visual control method (Oneþ and Zeki, 1987). The obtained values and climate data were evaluated together and the effect of abiotic factors was determined.
        
Statistical analysis
 
The relationship among the measured variables was evaluated using Pearson correlation and multiple regression analysis to identify factors that might affect exit from overwintering area of poppy root weevils in Turkey. SPSS for windows Version 16.0 was used for all statistical analyses. The analysis was performed by combining the average data obtained from field in the period ranging from 2014 to 2015. In multiple regression analysis the dependent variable was exit from overwintering area of poppy root weevils (individual) and the independent variables were soil temperature (5 cm), temperature, soil moisture, humidity and rain.

The first adults were seen on the soil on March 10, 2014. It has been observed that as the temperature of the air increases, the number of adults on the soil surface also increases. Thus, it was determined that the number of adults in square meters reached the highest level on April 21, 2014. After this date, it was determined that the number of wintering adults decreased gradually (Table 1).
 

        
While the first insect on the surface of the field was caught on March 09, 2015 in the second year. It was determined that the number of highest poppy root weevils caught on the soil surface and in the traps was on April 13, 2015. After this date, it was determined that both the trapped insects and their numbers in m² decreased. (Table 1).
        
There were significant (P≤0.05) correlations between the poppy root weevils’ exit from overwintering area and soil temperature (Fig 1, r=0.648, r²=0.461, n=84 P=0.000) and temperature (Fig 2, r=0.59, r²=0.277, n=84, P=0.004) whereas there was no significant correlation with soil moisture (r=0.310, r²=0.021, n=84, P=0.466), humidity (r=0.32, r²=0.108, n=84, P=0.87) and rain (r=0.38, r²=0.101, n=84, P=0.73).
 


Stepwise multiple regression analysis of the data revealed as the best model for the relationship between exit from overwintering area of poppy root weevils and abiotic factors, a model including soil temperature and temperature Y = -0.472 + 0.214 STEM + 0.125 TEM [where Y = exit from overwintering area of poppy root weevils (individual), STEM = soil temperature, TEM =  Temperature (°C)]. This model had the best correlation (r=0.600, r²=0.414 n=84 P=0.042). Stepwise multiple regression analysis of the data shows that soil temperature and temperature is significant for exit from overwintering area of poppy root weevils. The highest exit from overwintering area of poppy root weevils rate was observed in the towards the end of April, the lowest exit from overwintering area of poppy root weevils rate was found at the beginning of March. 
        
In our country, combat with poppy rootworm is recommended if there are 10 individuals in  one m². However, in the studies, the emergence times of poppy rootworms are not determined correctly, so they lay eggs until chemical struggle is made. Therefore, the struggle can be unsuccessful and two or three times chemical spraying can be required. In order to be successful in the chemical struggle against the poppy rootworm, it is necessary to determine the time of the pest’s exit from the soil. Observations made on the basis of the air temperature from time to time are sometimes unsuccessful and therefore the struggle is adversely affected. In order to prevent this, it is considered to be beneficial to consider the soil temperature. In this study, it was determined that the exit of the pest to the soil surface was directly related to the temperature and the soil temperature. It is thought that these findings will be beneficial in poppy rootworm struggle and early warning and prediction studies.
               
There is no study on the effect of abiotic factors on the time of the exit of the poppy rootworm from the soil. However, the effects of some abiotic factors on poppy rootworm were investigated. In a study conducted by Becka et al., they reported that existence of a dependency between the gradual increase in the occurrence of poppy root weevil adults and the gradual increase temperatures (over 14°C) calculated from the beginning of the emergence of the poppies (D. Bečka,2014). In addition, they stressed that sprays applied for 18 days after the first record of poppy root weevils in trials showed the highest effects on a decrease in the levels of root damage. Then they determined that applied sprays in temperatures higher than 20°C led to a significant decrease on the levels of root damage. But the highest effects were usually recorded in sprays which were applied in the sum of effective temperature value exceeding 100°C. (De Long et al., 1963). Ýslamoðlu (2017) stressed that; the most important factor in the emergence of the pests from soil to surface is temperature. Also, he reported that, in the second week of March in which effective temperature reached 14°C, the poppy root weevils started to emerge to the soil surface in 2014 and 2015 and peak of the poppy root weevils was determined to be in the second week of April. Also he reported that the sum of effective temperatures at this date was determined to be 70.6°C in 2014 and 90.4°C in 2015 and after the poppy root weevil’s emergence reached the peak, the first larvae began to appear about 10 days later. According to this, when the insect populations are the highest and the sum of effective temperatures is 70 - 90°C, it is suggested to make chemical struggle.