Population Density of Leaf Miner Lirimoyzatrifoliiand Cotton Aphid Aphis Gossypiiinfesting Castor Oil Plant Ricinuscommunis
Abstract
A field study was conducted at plan t protection department, college of Agriculture/University of Baghdad to determine castor oil plant pests Ricinuscommunis, for the period between 2/9/2014 to 17/6/2015. Results showed that castor oil plant (Ricinuscommunis) was infested by the castor oil p lant leaf minor Lirimoyzatrifolii and cotton aphidAphis gossypii. The highest population densities of the leaf minor at western side were 6.8 insect/leaf and the lowest were 0.6/leaf dated in 30/4,7/5 and17/6 , respectively. Whereas, the highest population densities at northern side were 5.6 insect /leaf recored in 9/9 while The lowest population densities of the leaf minor at northern side were 0.3 insect/lea f dated in 10/6,17/6 and 30/4 respectively. The highest population densities of the leaf minor at southern side were7.5 and the lowest were0.3insect/leaf dated in 3/6 , 2/1 respectively. At eastern side, the highest densities were 5.6 insect/leaf dated in2/9 and the lowest were 0 in 10/6 respectively . For cotton aphid, the highest population densities we re for the northern side with4.2 cm2/leaf discdated in 2/9and the lowest were 0 cm2/leaf disc dated in12/4 and 30/4 . Whereas they were 4.8cm2/leaf disc in 19/11 and 0cm2/leaf disc in 30/1and 30/4 for western as highest and lowest densities respectively the highest population densities for the eastern sides were 3.6 in 19/11 while the lowest population density were 0.3 in 23/1 ,30/1 , 22/2 ,23/4 and 7/5 ,the highest population densities for the southern side were 7cm2/leaf discin 23/4 while the lowest population density were 0.2 in 9/9 respectively. The highest incidence was for the parasite Pediobiusmetalicus. While, the hymenopteran Neochrysochairsformosa, Digylphuscrassinervis and Pediobiusmetalicus were reported to parastize on castor oil leaf minor.
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Introduction
Castor oil plant (Ricinuscommunis) belongs to the family Euphorbiaceae, is a shrub with five lobe leaves given a hand palm shape. About 50% of fruit weight contains an oil substance (Medical Encyclopedia, 2016).Euphorbiaceae is one of the biggest plant families as it includes 300 genera and 5000 species (Chiej, 1984). It is distributed worldwide, specifically in tropical area and extends to moderate area in North and South hemispheres, including tropical area of America and Africa (Banderjee et al 1990). About 44 genera belong to this family have been reported in Iraq. Seed of many euph or biaceous plants (like castor oil Ricinuscommunis) are very important due to their medical uses. Oil extracted from the seed contains several fatty acids including ricinoleic, oil and palmitic acids. it includes ricinine chloride as well. Castor oil is a very strongand effective laxative and used to treat skin scars, hay fever and other allergies (Duke and Ayensu, 1985). Castor oil plant is infested by several pest including the leaf minor Lirimoyzatrifolii and mites besides various diseases (W. and C. 2012) and (Z. et al 2012). Sharma et al (1980) indicated the presence of holes induced by Lirimoyzatrifolii females when oviposit .The tunnel made by larva feeding looks like a clear strip of about (0.25-1.5mm) in diameter inside the leaf. It damages the mesophilic tissue causing leaf drop. Chemical treatment controls (30-60%) of this pest when applied. While Stegmaier referred in (1995) that Lirimoyzatrifolii is well-known pest attacks celery, Chrysanthemum and 55 host plants and has wide range hosts in Florida. Lirimoyzatrifoliiisa very important pest on cotton, castor oil plant, tomato and cowpea. The life cycle rates range between 19.19 to 24.69 and 21.32 to 27.59 days for male and female, respectively. Whereas, fertility rate ranges between 64.1 to158 eggs and ovi position ratio ranges 1:537 to 1:855 (Sushila et al 1997). Anjani in (2005) showed the leaf minor L.trifoliican damage the mesophilic tissue and turn the parenchyma tissue into a white stripwhich affect photosynthesis process then destroy leaves of castor oil plant Ricinuscommunis.Palumbo (2012) reported L.trifolii and L.sativae have more than 55 host plants as they attack several hosts and spend the summer on cotton Malvaspp and annual crops. Capinera et al (2014) revealed pupae and adults feed on plant sap using their piercing-sucking mouth parts and reach phloem conductive elements which cause disruption in plant function, weaken the plant and leaf yellowing and drop. Aphids produce honey dew which drops on leaves and other plant parts then will be coated with sooty mold growth and dusts. These sooty coatings will reduce photosynthesis, respiration and transpiration processes of covered plant parts. Due to the Lirimoyzasp incidence on castor oil plants at the study location alongside the injury caused by this pest on several crops, this study was initiated to determine population density of the L.trifolii leaf minor and cotton aphid on castor oil plants, and to identify and calculate the percent of their parasitoides
