Sarhad J. Agric. Vol.27, No.2, 2011 245 EFFECT OF CONSUMPTION OF DIFFERENT HOSTS ON THE BODY WEIGHT OF SURFACE GRASSHOPPER, CHROTOGONUS TRACHYPTERUS LANCHARD (ORTHOPTERA PYRGOMORPHIDAE) TAJWER SULTANA SYED, MOHAN LAL, GHULAM HUSSAIN ABRO and SAIMA SIDDIQUI Department of Entomology, Sindh Agriculture University, Tandojam, Sindh – Pakistan. E-mail: [email protected] ABSTRACT A laboratory study was carried out during 2006 at the department of Entomology, Sindh Agriculture University, Tandojam, Pakistan to investigate the effects of consumption of different hosts on body weight of surface grasshopper, Chrotogonus trachypterus. Different host plants provided for the experiment were: okra, Abelmoschus esculentus L.; cotton, Gossypium hirsutum L.; china rose, Hibiscus rosassinensis L.; Akk, Calotropis procera AitR.Br and sunflower, Helianthsu annuus L. The highest average food consumption was recorded when C. trachypterus fed on sunflower (2.20 g), followed by okra (1.77 g) and cotton (1.73 g), the least consumption of food was recorded on china rose. The leaf area consumption (cm2) on different host plants varied significantly on different host plants. The highest body weight attained was on sunflower (0.1453 g) followed by cotton (0.1330) and okra (0.1265) respectively. Difference was also recorded on the longevity of C. trachypterus when fed on different host plants. Highest longevity was 116.8±4.515 days recorded on china rose and shortest on okra (109.6±3.682) days. Key Words: Cotton, sunflower, china rose, chrotogonus trachypterus, consumption Citation: Syed, T. S., M. Lal, G. H. Abro and S. Siddiqui. 2011. Effect of consumption of different hosts on the body weight of surface grasshopper, chrotogonus trachypterus Lanchard (orthoptera pyrgomorphidae). Sarhad J. Agric. 27(2): 245-249 INTRODUCTION Surface grasshopper, Chrotogonus trachypterus (Orthoptera: Pyrgomorphidae) is a multivorous and terricolous species, one of the common grasshopper species occurring in this region. Surface grasshopper adult is stout, mud-like in colour; polyphagous, feeding on foliage and tender shoots. They scatter on emergence and feed on almost any green vegetation, are injurious to germinating crops and may inflict severe damage to cotton. Adults and all hopper stages are found throughout the year but are less active during winter season (Gupta, 1999 and Anonymous, 2000). Feeding variations in C. trachypterus are associated with weather, gravitational forces, and complexities of food resources, habitat selection and differences in the food niche, non-synchronous lifecycle, and seasonal change in preference, sexual dimorphism, developmental polymorphism, conditioning, thirst, hunger, predation, parasitism and competition. It has been reported that berseem, cotton, mustard, lucerne, potato and tomato were consumed readily and were the highly preferred food plants by surface grasshopper (Asad et al. 2001). Akhtar (1971) reported that consumption of jute, Corchorus capsularis and berseem, Trifolium alexandrinum leaves by surface grasshopper Chrotogonus trachypterus were the highest, being 68.67 and 67.00 % respectively, followed by cotton, Gossypium hirsutum and sarson, Brassica campestris, with 60.67 and 45.00 % consumption, respectively. Jotwani and Butani (1978) reported Chrotogonus trachypterus feeding on pearl millet, berseem and cotton and inflicting considerable damage to the crops. Duranton and Launois (1979) discussed dietary variations of Chrotogonus trachypterus and reported that a greater number of allied species feed on wild plants. Ayyanna et al. (1978) mentioned that Chrotogonus trachypterus, Chrotogonus oxypterus and Atractomorpha crenulata were found as pests on sunflower. C. oxypterus killed young plants, soon after emergence, but the pest is only of minor importance. A. crenulata nymphs and adults feed on leaves, making irregular holes, and cause considerable damage. Launois and Launois (1976) studied feeding preferences of caged adults of grasshoppers when offered the choice of leaves of four plants (ground nut, Arachis hypogaea, bean, Vigna ungiculata millet, Pennisetum americanum and sorghum, Sorghum bicolor) and concluded that feeding preference tests could not accurately predict the distribution of grasshoppers in relation to different crops, which must involve other environmental factors. T.S. Syed, et al. Effect of consumption of hosts on the body weight of surface grasshopper … 246 Surface grasshopper, Chrotogonus trachypterus is a common pest that feeds on green vegetation and yet its feeding preference and subsequent effects on its body weight has not been studied extensively. Present studies were carried out to investigate the effect of different plants on food consumption and the body weight of C. trachypterus under laboratory conditions. MATERIALS AND METHODS The present research investigations were conducted under laboratory conditions. The observations were taken to study the effects of food consumption of different hosts on the body weight of surface grasshopper, Chrotogonus trachypterus during 2006 at the Department of Entomology, Sindh Agriculture University, Tandojam, Pakistan. A large number of nymphs and adults were collected from various fields of cotton, sugarcane and okra crops. The collection of insects was made from 9:00 to 12:00 noon with the help of insect collecting net and kept in rearing cage measuring 112x82x82 cm. Cotton leaves were provided for feeding until adult stage. Newly emerged adult male and female were paired in separate cage measuring 30x30x45cm for mating and oviposition. A glass beaker measuring (5x9 cm) containing moist soil was provided for oviposition. Ten pairs were kept for further observations. The eggs laid were kept in petridishes lined with moist filter paper for hatching. Newly hatched nymphs were separated and shifted into glass jars 15x5 cm individually. Different host plants provided for the experiment were: okra, Abelmoschus esculentus L.; Cotton, Gossypium hirsutum L.; China rose, Hibiscus rosassinensis L.; Akk, Calotropis procera AitR. Br and Sunflower, Helianthus annuus L. The food plant leaf, attached to a twig held in vial containing water for maintaining freshness of leaf was provided as food. Each glass jar was covered with muslin cloth and banded with rubber. The leaves offered as food were changed after every 24 hours and new leaves were provided. After 24 hours the amount of food (leaf tissue area) eaten, were collected and measured to calculate the amount of leaf eaten/ consumed by Chrotogonus trachypterus. A graph paper was cut to the size of leaf disc and weighed. Graph paper (6.45 sq cm) was weighed and with the help of this weight, the weight of graph paper disc was calculated. Similarly, the remaining portion of leaf discs left after by Chrotogonus trachypterus were measured on graph paper and cut accordingly. The weight of remaining portion of graph paper was deducted from the weight of the original and in this way the area of disc was calculated to get the consumed area of leaf disc. The newly hatched nymphs were weighed on electrical balance on weekly basis and different instars were noted on different foods offered. At the end of the experiment, the Chrotogonus trachypterus were weighed on electrical balance to analyse the consumption of different food plants. After final moult, adult grass hoppers were maintained on their respective food plants till death to determine the effect of host plant on adult longevity. Each experiment was replicated ten times and the data obtained were subjected to statistical analysis and significance was worked out to discriminate the deviation of treatment means. RESULTS AND DISCUSSION Food Consumption The data in Table I indicated that surface grasshopper, Chrotogonus trachypterus showed more preference for eating sunflower leaves and the average food consumption was 2.20g, while the insect showed next preference to consume okra and cotton leaves where average food consumption was 1.77 and 1.73 g, respectively. The surface grasshopper consumed 1.62 g of akk plant leaves and the China rose was the plant that was consumed minimally (0.53 g) by the insect during whole the life span. The sunflower plant was significantly (P<0.05) more preferred to be consumed by the grasshopper than other food plants, China rose was the least preferred food plant. There was a highly significant (P<0.01) correlation (r = 0.826) between leaf area eaten cm2, and food consumption (gm) by C. trachypterus in present study. Present results are partially supported by Akhtar (1971) who observed surface grasshopper feeding on cotton, Ayyanna et al. (1978), reported feeding on sunflower, whereas Sreenivasulu et al. (1996) have reported surface grasshoppers feeding on Calotropis sp. The choice of plants by the acridids seems to reveal that it may be based on the absence of feeding detergents or their presence in smaller amounts in the host plants. For instance O. nitidula totally rejected all forbes, perhaps due to the presence of one or more compound deterrent to the graminivore (Bernays and Chapman 1977). Abdel (2001) mentioned that the grasshopper was found all the year round. The consumption index differed significantly between groups fed on different diets. Sanjayan and Murugan (1987) reported that the early nymphal stages showed the highest growth rate on all the host plant plants. The approximate digestibility computed indicated all the host plants Sarhad J. Agric. Vol.27, No.2, 2011 247 provided were highly digested by the acridids.