Parasitism status of Bemisia tabaci (Gennadius 1889) (Hemiptera: Aleyrodidae) on different host-plants in the Çukurova region of Turkey 1,2 - PDF

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Türk. entomol. derg.,, (): 9-7 ISSN -9 Orijinal araştırma (Original article) Parasitism status of Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) on different host-plants in the Çukurova region

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Türk. entomol. derg.,, (): 9-7 ISSN -9 Orijinal araştırma (Original article) Parasitism status of Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) on different host-plants in the Çukurova region of Turkey, Çukurova Bölgesi nde Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) nin farklı kültür bitkilerinde parazitlenme durumu Amir Abdullahi Yousif MALIK Kamil KARUT ** Summary Populations changes of Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) and its parasitism status were monitored on different host-plants in the Çukurova Region (Yüreğir and Karataş districts) in 8 and 9. Samples were taken from cotton, cucumber, eggplant and soybean and pest numbers were counted in the laboratory. Each year, lower numbers of B. tabaci occurred in early July and increased to higher densities in August and September. Likewise, low parasitism rates by Eretmocerus mundus Mercet 9 and Encarsia lutea (Masi 99) (Hymenoptera: Aphelinidae) occurred in July and peaked in August and September. Er. mundus was observed to be more efficient on cotton, eggplant and soybean, but less on cucumber. The parasitism rates by Er. mundus on all host-plants were higher than those of En. lutea. While the highest parasitism rate of Er. mundus was found on soybean (7.9%) in the Yüreğir district, that of En. lutea was on eggplant (.%) in the Karataş district in 8. In 9, while the highest parasitism rate by Er. mundus was on cotton (.%) in the Yüreğir district, that of En. lutea was found on eggplant (.%) in the same district. These parasitism levels confirmed that Er. mundus and En. lutea are important parasitoids of B. tabaci in the Çukurova Region. Key words: Bemisia tabaci, Eretmocerus mundus, Encarsia lutea, host plant, parasitism Özet Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) nin populasyon gelişimi ile parazitlenme durumu, Çukurova Bölgesinde (Karataş ve Yüreğir ilçelerinde) 8 ve 9 yıllarında farklı kültür bitkilerinde ortaya çıkarılmıştır. Yaprak örnekleri hıyar, pamuk, patlıcan ve soya bitkilerinden alınarak laboratuvarda sayılmıştır. Her iki yılda da Temmuz başında düşük olan B. tabaci yoğunluğu, Ağustos ve Eylül aylarında artmıştır. Benzer şekilde Temmuz ayında düşük olan, Eretmocerus mundus Mercet 9 ve Encarsia lutea (Masi 99) (Hymenoptera: Aphelinidae) ya ait parazitleme oranları, Ağustos ve Eylül aylarında yükselmiştir. Er. mundus pamuk, patlıcan ve soya bitkilerinde hıyar bitkisinden daha etkili bulunmuştur. Er. mundus a ait parazitleme oranı tüm kültür bitkilerinde En. lutea ya ait parazitleme oranından daha yüksek bulunmuştur. 8 yılında Er. mundus a ait en yüksek parazitleme oranı Yüreğir ilçesindeki soya tarlasında (% 7.9) elde edilirken, En. lutea için bu değer %. ile Karataş ilçesindeki patlıcan tarlasından elde edilmiştir. İkibin dokuz yılında Er. mundus a ait en yüksek parazitleme oranı Yüreğir ilçesindeki pamuk tarlasında (% ) elde edilirken, En. lutea için bu değer % ile aynı ilçedeki patlıcan tarlasından elde edilmiştir. Elde edilen parazitlenme oranları Çukurova Bölgesi nde Er. mundus ve En. lutea nın B. tabaci nin önemli parazitoitleri olduğunu göstermiştir. Anahtar sözcükler: Bemisia tabaci, Eretmocerus mundus, Encarsia lutea, kültür bitkisi, parazitlenme A part of this study was presented as an abstract for the Third Plant Protection Congress of Turkey, held in Van from 8 July 9 and this study is part of the PhD thesis of Amir. A.Y. Malik Agricultural Research Corporation (ARC), Wad Medani, Sudan Çukurova University, Agricultural Faculty, Department of Plant Protection, Adana, Turkey * *Sorumlu yazar (Corresponding author) Alınış (Received):.. Kabul ediliş (Accepted):.. 9 Parasitism status of Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) on different host-plants in the Çukurova region of Turkey Introduction Various species of whiteflies have been reported in association with annual crops, but none of them is as cosmopolitan as Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) which is commonly associated with cotton, tobacco and sweet potato. Bemisia tabaci has a range of around plant species within 7 families (Stansly & Naranjo ), but is often found on crop species belonging to the following plant families: Convolvulaceae, Cucurbitaceae, Leguminosae, Malvaceae, and Solanaceae (Byrne et al. 99). In Turkey, B. tabaci was reported to be a problem on different cultural plants as early as 98 (Arık et al.97). Although its populations differ annually, it is still considered the key pest in the Çukurova Region, causing yield reduction and economic losses (Özgür & Şekeroğlu 98; Şekeroğlu et al. ; Karut & Akdağcık ). Ever since an outbreak in 97, it has been the most important pest of cotton under irrigated conditions and research has increased over the years to develop solutions (Şengonca 97; Şekeroğlu et al., ). The high populations of B. tabaci have resulted in a large increase in the use of insecticides in the Çukurova Region. The number of applications per season has reached as high as ten and yet these costly applications of insecticides have hardly prevented economic losses. Insecticides often become ineffective against B. tabaci due to the development of resistance in its populations (Özgür & Şekeroğlu 98). Currently, the most common management approach is with pesticides; however, more efficient and environmentally sound methods are needed. Biological control through augmentation of natural enemies would be a more suitable approach if it was more consistent and effective. However, the success of parasitoids in biological control is highly variable, depending on host-plant interaction, climate, the presence of competing natural enemies, use of non-selective insecticides and a number of other environmental factors (Butler & Henneberry 98; Hoelmer 99). Studies have shown that host plant species can affect the abundance of whiteflies, as well as parasitoid abundance and rate of parasitism. Simmons et al. () reported that two Brassica species and Vigna anguiculata (L.) were more conducive to parasitism of B. tabaci than Cucumis sativus L. and Lycopersicon esculentum Miller. Qiu et al. () demonstrated that Eretmocerus sp. nr. furuhashii Rose and Zolnerowich was more effective on non-glabrous crop varieties than glabrous plants for biological control of B. tabaci. Stansly et al. (997) found that a greater proportion of B. argentifolii was parasitized by Encarsia pergandiella Howard 97 on tomato than on collard and eggplant in a greenhouse choice test. Karut & Naranjo (9) hypothesized that the key to understanding parasitism was based on graphical and regression-based comparisons of individual k-factor values to total generational mortality. The authors related this to cotton planting in the Çukurova Region where the crop is surrounded by a relatively diverse cropping landscape that may more readily facilitate higher parasitoid populations and thus contribute to higher pest mortality. However, there are no detailed studies on parasitism of B. tabaci on different crops surround the cotton plants in the region. The diverse cropping landscape in the Çukurova Region includes eggplant, cotton, cucumber and soybean, all important host-crops of B. tabaci. Eggplant and cucumber are normally grown in a few, small areas whereas cotton and soybean are grown in much larger areas. Cotton is sometimes grown as a second crop in June, but mainly as a first crop beginning in mid April to mid May and soybean is normally grown as a second crop with planting in June. Although studies have shown that Eretmocerus mundus Mercet 9 and Encarsia lutea (Masi 99) are important parasitoids and a key factor in managing the populations of B. tabaci on cotton in the Çukurova Region (Kaygısız 97; Ulusoy et al. 99; Karut ; Karut & Akdağcık ; Karut & Kazak 7; Karut & Naranjo 9), there are no detailed studies on other host-plants grown in the region. The present study was carried out to determine the parasitism status of Er. mundus and En. lutea on B. tabaci Malik & Karut, Türk. entomol. derg.,, () on eggplant, cucumber, soybean and cotton and to help develop effective and more sustainable pest management systems to control B. tabaci populations in the Çukurova Region. Material and Methods To determine the parasitism status of B. tabaci on cucumber (Cucumis sativus L.), eggplant (Solanum melongena L.), cotton (Gossypium hirsutum L.) and soybean (Glycine max (L.) Merr.), surveys were carried out in commercially sprayed fields located in the Yüreğir and Karataş districts of the Çukurova Region during the 8 and 9 growing seasons. In 8, whitefly abundance and parasitism rates were evaluated in six different fields; three (cotton, eggplant and soybean) located at Karataş, and the others (cotton, cucumber and soybean) at Yüreğir district of Adana. In 9, similar studies were conducted at seven fields; three (cotton, eggplant and soybean) located at Karataş and the others (cotton, eggplant, soybean and cucumber) were in the Yüreğir district of Adana. The average monthly temperatures for June-September in this region ranged between and 9. C. A summary of the information for the fields sampled in 8 and 9 seasons is given in Table. The type of insecticides used to control B. tabaci varied by field and over time. The number of sprays varied between two to six per season and the more commonly used insecticides were Imidacloprid, Pyriproxyfen, Acetamiprid, Diafenthiuron, Chlorpyriphos and Cypermethrin. Table. Sites used to determine the parasitism status of Bemisia tabaci in Çukurova Region, in 8 and 9 Season Host-plant Variety Location Area (hectares) 8 Cucumber Altay Yüreğir Eggplant Adana topağı Karataş ~. Cotton A SG Yüreğir.8 Cotton B SG Karataş Soybean A SA 88 Yüreğir Soybean B SA 88 Karataş 9 Cucumber Altay Yüreğir. Eggplant A Adana topağı Yüreğir. Eggplant B Adana topağı Karataş. Cotton A SG Yüreğir Cotton B SG Karataş. Soybean A BLAZE Yüreğir Soybean B SA 88 Karataş Sampling commenced in June and continued for weeks in both years. On each sampling date, leaves from each field were randomly selected ( from the upper half of the plant from. rd or th node leaves and from the lower half of the plant from. th or 7th node leaves). They were covered carefully with paper, labeled, put in plastic bags, stored in a slightly cold container and brought to the laboratory where a random area of cm² on the lower part of each leaf was selected for the counting of eggs, larvae, pupae and exuvia of B. tabaci; and pupae of Er. mundus and En. lutea, using a binocular microscope. Parasitism without meconia in the parasitized pupae was attributed to Er. mundus, and parasitism with meconia to En. lutea (Otoidobiga et al. ). Percent parasitism was calculated as the quotient of the total number of parasitized whitefly and the total number of parasitized plus unparasitized whitefly. Data on percentage parasitism and B. tabaci stages on different host-plants were subjected to analysis of variance (ANOVA), and mean percentages were separated using the Least Significant Difference Test (LSD) following a significant F test at P . (Microsoft Excel, MstatC). Percentage data were arcsin transformed before analysis. Parasitism status of Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) on different host-plants in the Çukurova region of Turkey Results B. tabaci is a species complex that includes different biotypes. Although biotypes of B. tabaci were not determined for this study, earlier studies show that B and Q biotypes are present together in the region (Karut, 9). Weekly mean number of immature stages of B. tabaci was lower on cotton than cucumber, eggplant and soybean in 8 (Figs. and ). While mean number of eggs never reached more than. per cm on cotton, it averaged on cucumber plants in 8. In general, the whitefly population in 9 was lower than the population in 8 on all host-plants, except for cucumber. Mean numbers of immature stages of B. tabaci on cotton, eggplant and soybean were lower than on cucumber plants and never reached more than nymphs per cm in 9 (Figs., and ). The parasitoid species found in all sampled fields were the native species, Er. mundus and En. lutea (Ulusoy et al 99; Karut ; Karut & Kazak 7). In general, population fluctuations of Er. mundus and En. lutea were similar to that of B. tabaci. On all host-plants in the two growing seasons, low weekly mean numbers of B. tabaci occurred in early July, and increased to higher densities in August and September. Likewise, low weekly parasitism rates occurred in July and peaked in August and September (Figs., and ). Eggplant 8 Mean number of Bemisia tabaci / Mean # of Bemisia tabaci/ cm cm Cotton A. Soybean A Eggs Cotton B Larvae+pupae+exuvi Er. mundus En. lutea Soybean B % parasitism Sampling dates Figure. Weekly mean numbers of Bemisia tabaci and parasitism rates of Eretmocerus mundus and Encarsia lutea on eggplant, cotton and soybean during the 8 season at the Karataş and Yüreğir districts of Adana. Arrows indicate the dates of insecticide applications for whitefly. Host-plant with A and B indicates Yüreğir or Karataş district, respectively. Malik & Karut, Türk. entomol. derg.,, () Eggs Larvae+ pupae+ exuvi Er. mundus En. lutea 9 Mean number of Bemisia tabaci / cm Mean # of B. tabaci/ cm % parasitism Sampling dates Figure. Weekly mean numbers of Bemisia tabaci and parasitism rates of Eretmocerus mundus and Encarsia lutea on cucumber during the 8 and 9 seasons in the Yüreğir district of Adana. Arrows indicate the dates of insecticide applications for whitefly. In 8, the highest parasitism rate by Er. mundus was obtained on soybean A (7.9%) in Yüreğir in the second week of September and that by En. lutea was on eggplant (.%) located in Karataş in the first week of September (Fig. ). Although the populations of B. tabaci on cucumber were higher than on cotton, eggplant and soybean plants, the weekly parasitism rates were lower for both parasitoids. The highest weekly parasitism percentages for Er. mundus and En. lutea in 8 were % in the second week of September and.% in the second week of June, respectively, on cucumber (Fig. ). In 9, the highest parasitism rate by Er. mundus was on cotton A (%) located in Yüreğir on August 8 and by En. lutea was on eggplant (%) on June in the same area (Fig. ). The seasonal mean numbers of B. tabaci eggs were higher on cucumber plants than on other host plants in both seasons (F =., df = 7, P =. for 8; F =., df = 8, P =. for 9), in spite of the early insecticide applications. Similar to the egg stage, the seasonal mean number of larvae was higher on cucumber than on the other host plants in 9 (F =., df = 8, P =.). Seasonal parasitism rates by Er. mundus were highest on soybean and eggplant followed by cotton in the 8 and 9 growing seasons (F =., df = 7, P =. for 8; F =., df = 8, P =. for 9). The lowest parasitism rates by Er. mundus were on cucumber plants for both 8 and 9 (mean=. and.78%, F =., df = 7, P =. for 8; F =., df = 8, P =. for 9). In the 8 and 9 growing seasons, the parasitism rates by Er. mundus on all host plants were higher than those by En. lutea. Similar to Er. mundus, the highest parasitism rates by En. lutea were on soybean and the lowest were on cucumber plants (Table ). Parasitism status of Bemisia tabaci (Gennadius 889) (Hemiptera: Aleyrodidae) on different host-plants in the Çukurova region of Turkey 7 Eggplant A 7 Eggplant B Mean number of Bemisia tabaci / Mean # of B. tabaci/ cm cm Eggs Larvae+pupae+exuvi Er. mundus En. lutea Cotton A Soybean A Cotton B Soybean B % parasitism Sampling dates Figure. Weekly mean numbers of Bemisia tabaci and parasitism rates of Eretmocerus mundus and Encarsia lutea on eggplant, cotton and soybean during the 9 season at the Karataş and Yüreğir districts of Adana. Arrows indicate the dates of insecticide applications for whitefly. Host plant with A or B indicates Yüreğir or Karataş district, respectively. Table. Seasonal mean numbers of Bemisia tabaci stages and parasitism (%) on different host plants in the Çukurova Region in the 8 and 9 growing seasons Seasons Bemisia tabaci stages % parasitism Host-plant Egg Larvae Eretmocerus mundus Encarsia lutea 8 Cucumber 9.9 ±. a*. ±. b. ±.79 c.7 ±. b Eggplant. ±. b 8. ±. a 8. ±.8 a.79 ±.8 ab Cotton A. ±. b. ±. b.8 ±. c. ±. b Cotton B. ±. b.8 ±. b 7.7 ±.77 bc.98 ±.9 a Soybean A.9 ±. b. ±.7 a. ±.77 ab. ±. a Soybean B. ±. b. ±. b 9.9 ±.8 abc.98 ±.7 a 9 Cucumber.8 ±.7 a. ±.8 a.78 ±.9 b. ±.9 d Eggplant A.7 ±. b.7 ±. b. ±.9 a.7 ±.8 abc Eggplant B.7 ±. b. ±. ab 7. ±.9 ab. ±.9 bcd Cotton A. ±. b. ±.8 b 8.8 ±. ab. ±. cd Cotton B.7 ±. b.7 ±. b 9.7 ±. ab.9 ±. bcd Soybean A. ±. b. ±. b. ±.9 a 8.8 ±. a Soybean B.7 ±. b.7 ±. b. ±. a 7.7 ±.9 ab *According to the LSD test, means in the same column in the same year followed by the same letter do not differ significantly (P .). Malik & Karut, Türk. entomol. derg.,, () Discussion We found low weekly mean numbers of B. tabaci in early July that increased to higher densities in August and September on all host plants in the two growing seasons. These findings are similar to those of Özgür et al. (989) and Karut et al. (). Özgür et al. (989) used yellow sticky cards to monitor B. tabaci in Çukurova and reported that most of the B. tabaci population overwintered in the foothills on Cistus spp. which are the main winter hosts. Dispersal into cultivated crop areas began in April. They also reported low population densities until the end of July in cotton and other crops. Thereafter, large numbers of adults occurred in August and September in the Çukurova Plain area. Similar results were reported by Karut et al. () who determined the flight activities of adult B. tabaci by monitoring with plastic cup traps (CC trap) (Chu et al. ). In spite of several insecticide applications, the whitefly population on cucumber was higher than on the other host plants. This may be due to lower parasitoid populations on this host plant or due to inadequate penetration of insecticide sprays into the canopy of the low-growing cucumber crop. Another possibility is that cucumber may be a much better host for B. tabaci than the other host plants, resulting in a more rapid increase of whiteflies. Lower parasitoid numbers have been recorded on cucumbers in a number of previous studies and were attributed to the negative effects of leaf hairs on the cucumber plants which constrain walking speed and searching pattern of the parasitoids (Hulspas-Jordaan & van Lenteren 978, van Lenteren et al. 99, Gruenhagen & Perring, Qiu et al. ). In addition, we considered that not only were the numbers of trichomes on cucumber leaves important, but that the type of trichome may also have affected the efficiency of parasitoids. In our early trichome studies, we found that the numbers of trichomes on cucumber and eggplant were not significantly different from each other (data not presented), but that the populations of the two parasitoids had been lower on cucumber than eggplant. Sumathi et al. (8) reported that normally the trichomes on cucumber were long, thick and non-glandular and were abundant on the leaf lamina. However, under open field conditions, both glandular and non-glandular trichomes were present on cucumber leaves. This is a finding that was also reported by Gruenhagen & Perring (). In addition, these authors reported that parasitism by Er. eremicus Rose & Zolnerowich 997 was lower on velvetleaf than on all other hosts (camphorweed, cantaloupe melon and cotton), and partially attributed the difference to exudate from glandular trichomes of velvetleaf that entrapped parasitoids. The results from our study showed that parasitism levels by Er. mundus were almost the same on soybean,
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