Pak. J. Agri., Agril. Engg., Vet. Sci., 2011 ISSN 1023-1072 Pak. J. Agri., Agril. Engg., Vet. Sci., 2011, 27 (1): 51-65 SURVEY OF MEALYBUG, PHENACOCCUS SOLENOPSIS (TINSLEY) AND EFFECT OF BIO-ECOLOGICAL FACTORS ON ITS POPULATION IN DIFFERENT ECOLOGICAL ZONES OF SINDH 6 H. A. Sahito1, G. H. Abro1, R. Mahmood2 and A. Q. Malik1 1Department of Entomology, Sindh Agriculture University Tandojam, Pakistan 2Center of Agriculture and Bio-science, (CABI), Rawalpindi, Pakistan ABSTRACT The study on the effects of bioloigical factors on the population of mealybug was conducted in different locations of Khairpur (Mir’s), Naushahro Feroze, Sanghar, Matiari, Hyderabad, Mirpurkhas, and Tando Allahyar districts throughout season at fortnightly intervals. Results indicated a new mealybug specie Phenacoccus solenopsis Tinsely was identified from the British Natural History Museum through help of CABI (South Asia) which appeared on cotton two months after sowing and remained till harvest of the crop in all Farms. The pest infestation was more severe during 2007 compared with 2008 which may be due to increased parasitization of pest by a hymenopteran parasitoid, Aenasius bambawalei Hapat first time recorded in Pakistan during August, 2008 and population development and activity of predators. There was a significant reduction in overall pest population during 2008 compared with 2007 which may be due to a significant overall increase in predator activity in cotton fields throughout study area in 2008. The highest and the lowest pest population 106.21±15.29 and 55.21±18.71 of mealybugs per twig per plant was recorded during 2007 at Mirpurkhas and Tando Allahyar, respectively. However, during 2008, the highest and the lowest population 58.30±12.42 and 18.34±5.32 of mealybugs per twig per plant was recorded from Naushehro Feroze and Tando Allahyar, respectively. The predators population recorded during 2007 was highest at Mirpurkhas 1.73±0.37 per plant and the lowest 0.19±0.08 predators per plant observed from Tando Allahyar. The higher predators activity was recorded during 2008 compared to 2007. The highest predators population was 11.96±2.83 per plant observed at Nashahro Feroze and the lowest 2.29±0.79 per plant found at Tando Allahyar. The predators such as Coccinella spp., Chrysoperla sp., Geocoris sp., Orius sp. Spiders were found active feeding on mealybug population at all different varieties and farms during both seasons. Keywords: Aenasius bambewalei, cotton, Phenacoccus solenopsis, pest infestation, predators Corresponding author: [email protected]. 51 Pak. J. Agri., Agril. Engg., Vet. Sci., 2011 INTRODUCTION Cotton, Gossypium hirsutum L. is the most important fiber crop of Pakistan and in the world. It is used in textile as well as in oil industries and earns foreign exchange through export in shape of raw cotton, cotton yarn, cloth, garments and other cotton made products. It provides about 80% of national edible oil (Agha, 1994). The cotton provides raw material to 550 textile mills, 1150 ginning factories and 5000 oil mills (Ghani, 1998). In Pakistan, the eruption of mealybug on cotton and other plants was first recorded at Vehari Agriculture Farm, during 2005. It has now spread throughout the cotton growing areas and is continuously affecting the crop yield. In 2006, it was seen in epidemic form at Multan, Bahawalpur, Vehari and Khanewal. Cotton yield suffered a severe setback due to the attack of this insect (The daily Dawn, 2006). In Sindh, southern winds blow from May to September and the intercropping are very common which might have favoured this pest to infest cotton. Situation in Sindh was even worse than Punjab. Severe infestation of mealybug was recorded first time on an area of about 3000 acres in Kot Ghulam Mohammad, Tando Allahyar, Tandojam, Mirpurkhas and Sanghar district in 2005 and 2006. The mealybug species are widespread throughout the world. Mealybugs are found outdoors in the warmer climatic zones of India, Pakistan, America, Europe, Africa, and Hawaii. They produce a large amount of honeydew which is responsible for the development of a black fungus commonly known as sooty mold (Gullan and Kosztarab, 1997). Mealybug species have been found on a relatively wide variety of host plants including species of economically important families such as Cucurbitaceae, Fabaceae, Solanaceae and Malvaceae. The Phenacoccus solenopsis was first recorded in Brazil, infesting tomato plants was found on common weeds in Manguinhos indicating that mealybug originating from nearby weeds might had infested those crops. The feeding of mealybug may cause leaf yellowing, defoliation, reduced plant growth and in some cases death of plants (Culik and Gullan, 2005). A similar out break of mealybug on cotton was also recorded at Gujrat, India (Muralidharan and Badaya, 2000). Wale, (2000) described that the level of damage caused by mealybugs on potato is steadily increasing in Adet area. As storage time increases mealybugs increase in large numbers, feeding on the tuber contents by sucking with their stylets and causing the tuber to shrink. The nymphs and adults form colonies mostly at the bases of the sprouts and on the eyes of the tuber. The insect produces a cotton-like mass that covers the tuber and eventually the tuber rots. The level of mealy bug infestation varied greatly with the cultivar in storage, with some showing no sign of damage and others being completely damaged. Different integrated pest management strategies are being tried in affected areas, for control at this pest which includes biological control, physical control, use of resistance varieties as cultural control that offers ecological and economic sustainability of farming systems by reducing both the risk of crop losses and the risk to human health from insecticide use. These 52 Pak. J. Agri., Agril. Engg., Vet. Sci., 2011 approaches are not only friendly to human health and the environment, but also self-perpetuating. The benefit-cost ratios are correspondingly high (Zeddies et al., 2001). Keeping in view the out break of mealybug on cotton crop and use of different controlling strategies as IPM tool “Survey of mealybug, Phenacoccus solenopsis (Tinsley) and effect of bio-ecological factors on its population in different ecological zones of Sindh” was conducted so that destruction of cotton crop may be saved in cotton growing areas of Sindh. MATERIALS AND METHODS The survey for infestation of P. solenopsis on cotton crop was conducted at different locations of Sindh (Figure 1). The studies on survey of cotton mealybug and effect of bio-ecological factors on the population of mealybug in different ecological zones of Sindh, were conducted in seven districts from cultivation till harvest of crop 2007-08. The places selected for the survey are shown in Table 1. Survey was conducted from sowing till harvesting of crop at fortnight intervals. One progressive farmer was selected from each district and study was conducted on his farm. Out of his cotton crop, one acre was selected at random and put under study. Thus, observations on infestation of P. solenopsis started one month after sowing of cotton crop. Most infested plants and patches were observed and highlighted with the red cloth ribbon for checking the spreading of mealybug on cotton. Sampling method of P. solenopsis its predators and parasitoid For taking observation, 25 plants were observed randomly from 5 different locations i.e. five plants from each corner and one from centre, if infested patches were found, those were highlighted for recording mealybug along with predators and parasitoids. As mealybug developed population to out break level and started affecting crop adversely, farmers used pesticides to control the pest population from completely devastating the crop. Therefore, the data were taken from one acre kept free from pesticides to check the population growth of pest and predators, and to encourage parasitoids to establish their population and exert their full potential in population regulation of pest. The plants were thoroughly examined, only adult mealybugs with visible crawlers and predators population were counted. During survey, the infestations at different phenalogical stages were recorded. In the field the distribution of mealybug population was also recorded to observe, whether mealybug is uniformly distributed or in patches and if there was influence of wind, water or weeds, (alternative hosts) etc. so that, the most preferred alternate host plants of mealybug could be exploited for mealybug control in cotton field. The agro-ecosystem/ cropping pattern surrounding cotton and within cotton was also evaluated. The data on effect of climatic factors on the population growth of mealybug in different ecological zones were taken from the nearest Government Meteorological centers working at Tandojam, Mirpurkhas and Sukkur. The different zones have their own Temperature, Relative humidity, wind velocity and rain fall conditions. 53 Pak. J. Agri., Agril. Engg., Vet. Sci., 2011 When mealybug parasitized mummies were first observed in the second fortnight of August, 2008 from different districts of Sindh, the 25 twigs were cut from the plant along with mealybug and brought into laboratory in petridishes or in transparent plastic bags individually and kept for emergence of parasitoids. When the adult parasitoids emerged, they were counted and percent parasitiztion was worked out. The data on parsitization was collected till harvest of the crop from every farm under study. Table 1. Details of survey