Parasitoid Wasps Attacking the American Serpentine Leafminer Liriomyza Trifolii in Kafr EL-Shiekh, Egypt
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International Journal of Zoological Investigations Vol. 3, No. 1, 15-20 (2017) ______________________________________________________________________________________ International Journal of Zoological Investigations Contents available at Journals Home Page: www.ijzi.net ISSN: 2454-3055 Parasitoid Wasps Attacking the American Serpentine Leafminer Liriomyza trifolii in Kafr EL-Shiekh, Egypt Rowfida A. Bassiony1,2,*, Abou-attia F.A.3, Samy M. A.2, Asmhan E. Youssef3 and Ueno T.1 1 Institute of Biological Control, Faculty of Agriculture, Kyushu University, Fukuoka, Japan 2 Plant Protection Research Institute, ARC, Sakha, Kafr El-Sheikh, Egypt 3 Economic Entomology Department, Faculty of Agriculture, Kafrelsheikh University, Egypt *Corresponding author Received: 30th March 2017 Accepted: 25th April 2017 _______________________________________________________________________________________________________________ Abstract: Dipteran leafminers of the genus Liriomyza are important pests of many vegetable crops worldwide. In Egypt, broad bean yield had been severely harmed in recent years due to dipteran leafminer infestations. Biological control with parasitoids is known as an effective measure to reduce leafminer damage. In the present study, we first examined the composition of parasitoid species and parasitism rates of parasitoid wasps attacking L. trifolii to highlight the importance of parasitoids in regulating leafminer populations on bean fields in Kafr EL-Shiekh, Egypt. Then, the effects of plant species, weather factors and planting dates on the parasitism rate of parasitoid wasps were investigated, in order to examine how the above -mentioned factors influence the impact of the parasitoids on leafminer populations. Two parasitoid wasps Opius dissitus and Diglyphus isaea were commonly found on broad bean (faba bean) and French bean fields. These parasitoids were detected throughout the growing season of bean plants, though the parasitism rates were relatively low. Parasitism rates were significantly higher in French bean than in broad bean, suggesting host plant preference in the parasitoid species. Temperature and precipitation appeared not to affect the parasitism rates. Key words: Biological control, host plant preference, pest management, Agromyzidae _______________________________________________________________________________________________________________ Introduction Dipteran leafminers belonging to Legumes are of special importance as staple the genus Liriomyza (Diptera: Agromyzidae) food all over the world and are cultivated in are a group of herbivores whose larvae many countries (Mounir et al., 2015). In settle in plant leaflets, feeding on mesophyll Egypt, broad bean or faba bean Vicia faba L. tissue (Johnson et al., 1983; Parrella et al., and snap bean Phaseolus vulgaris L. are 1985; Salvo and Valladares, 2007). At major bean crops; the former bean is one of present, more than 20 Liriomyza species are the oldest crops and occupies the third most of economic importance as pest important grain legumes whereas the latter (Anonymous, 2009). The American is notably a pioneer Egyptian export crop serpentine leafminer L. trifolii (Burgess) is (Nassib et al., 1991; Anil et al., 2013). one of the most major pests of many vegetables, ornamental and horticultural However, it is not known whether the plants worldwide (Spencer, 1972). Control predominant parasitoid is D. isaea or the of leafminers is thus essential to stable other parasitoid in other regions of the production of marketable vegetables (Salvo country. Parasitoid fauna of the leafminers and Valladares, 2007; Liu et al., 2009). in many region of Egypt still remains In Egypt, leafminers including L. unclear. trifolii cause economically serious damage Our previous study has shown that in and loss of many vegetables including bean Kafr EL-Shiekh Governorate, L. trifolii is a crops (Abul-Nasr and Assem, 1961; Shahein serious pest of bean plants and exploring and El-Maghraby, 1988). Such leafminers effective parasitoid agents are on strong are often difficult to control solely by demand (Rowfida et al., in prep.). Thus, the chemical insecticides (Parrella et al., 1984). aim of the present study is to determine the Instead, biological control with parasitoids species composition and parasitism rate of or integrated pest management with parasitoid wasps that attack L. trifolii on biocontrol measure can be a promising bean plants in Kafr EL-Shiekh, Egypt. The measure to manage the leafminers (Salvo present study also examines how bean and Valladares, 2007; Liu et al., 2009). More species and abiotic factors could affect the than 140 species of parasitoids have been parasitism rate of the parasitoids detected. reported to attack Liriomyza leaf-miners, Materials and Methods and such natural enemies are often the most reliable agents of mortality of Liriomyza The field study was carried out in order to leafminers (Liu et al., 2009). Several species obtain parasitoids attacking L. trifolii. For this purpose, four different fields of broad of leafminer parasitoids have been commercially mass-reared and been used bean with different planting dates were set up and field sampling was made from the against Liriomyza in greenhouses or in the field (Liu et al., 2009). earliest growing stage of bean to just before Although parasitoids are useful in harvest. Sampling was initiated when bean plants were one month old, and continued leafminer management, the species composition is greatly variable depending once per week until the beans were harvested. Thus, sampling was done on the season and region, and, hence, it is important to determine parasitoid species from15/12/2015 to 15/03/2016, from 29/12/2015 to 16/03/2016, and from that are effective in the region and/or 12/01/2016 to 22/03/2016 for each of the season concerned (Tran et al., 2007; Mujica and Kroschel, 2011; Ueno and Tran, 2015). three fields of broad bean var. Giza 3 and Also, effective species of parasitoids may one field of Snap bean var. Giza 6 from 15/12/2015 to 15/03/2016 in Kafr El- depend on crop species or variety (Martin et Sheikh Governorate. al., 2006; Musundire et al., 2012). In Alexandria, Egypt, D. isaea has recently been In each study field, four points were shown as the most predominant species and randomly selected, and 25 leaflets were positively correlated with the leafminer collected from each collection point. When population (Naema and Hegazi, 2014). collecting sample leaflets, the cross- 16 diameter method was used from each plant; Results and Discussion one leaf was picked from all different plant In the present study, leafminers in our height levels. The collection was made at a region were identified as Liriomyza trifolii. weekly basis. Collected leaflets were Two parasitoid species were obtained; they returned to the laboratory, and the numbers were identified as Opius dissitus and of leafminer larvae were examined. The Diglyphus isaea, and were collected from sampled leaflets from each replicate were all broad bean and French bean fields. The placed separately into Petri dishes (10 cm diam.), and were kept in a growth chamber at 25 ± 2 ºC, 70 ± 5% RH, with a photoperiod of 14:10 h (L: D) for the emergence of adult leafminer and parasitoids. The samples in each Petri dish were checked every day for leafminer pupae and larval parasitoids. When leafminer pupae were found, they were carefully separated from the leaflets, and transferred into a new Petri dish (10 cm diam.) to record their Figure 1: The effect of planting date on Opius dissitus origin. The number of pupae from each parasitism rate on both bean crops replicate was recorded. The pupae were mean parasitism rates for each field were; placed in the same growth chamber for 6.4% vs 2.0% for broad bean field 1, 4.7% vs further development into adults. The 2.1% for field 2, 8.7% vs 1.6% for field 3, while 18.3% vs 3.6% for French bean numbers of emerged adults of L. trifolii and field (shown as Opius vs Diglyphus). The of its parasitoids, from the pupae were recorded and were identified. Likewise, larval parasitoids emerging were collected and were identified. The Liriomyza spp. were identified using external morphology and male aedegous (Spencer, 1972). Also, the parasitoids were identified according to the keys given by Chao-Dong and Da-Wei (2001), Gates et al. (2002) and Yefremova et al. (2011). Figure 2: The effect of planting date on Diglyphus Parasitism rates were calculated as isaea parasitism rate on both bean crops the number of parasitoids/total number of parasitism rates were then statistically leafminer larvae + parasitoids (for analyzed after arcsine square root parasitoids emerging from leafminer larvae) transformation with a paired t-test with the and the number of parasitoids/number of four fields as x-grouping. The analysis leafminer pupae (for parasitoids emerging from host pupae). Data were analyzed using revealed that the mean parasitism rates of Opius parasitoids were significantly higher JMP software (SAS Institute). than those of Diglyphus (n = 187, F = 4.80, 17 P = 0.003) while the parasitism rates O. dissitus is a solitary koinobiont differed among the fields (F = 7.68, P< parasitoid wasp attacking Liriomyza spp., 0.0001). Therefore, Opius parasitoids were and is reported from Africa, Europe and Asia more abundant than Diglyphus parasitoids. (Neuenschwander, 1987; Bordat, 1995). Both of the two parasitoids were Like other members of koinobiont detected in all fields throughout the growing parasitoids of