Introduction

1. Monitoring Insects in Sweetpotatoes with Sweep Net and Sticky Traps across the Mississippi Delta: A comparative study Tahir Rashid, Abdullah Muhammad, Craig Abel2 & Larry Adams2 Alcorn State University, Alcorn State, MS 2 USDA-ARS, SIMRU, Stoneville, MS a a a a a a a b b a b b b b b b Fig. 2. Click beetles collected in traps Fig. 3. Lygus lineolaris collected in traps Table 1. Mean number of insects collected in purple traps on different dates Table 2. Mean number of insects collected in purple traps at different locations a a a a a a a b a b a b b b b a Fig. 4. Tortoise beetles collected in traps Fig. 5. Spotted cucumber beetles collected in traps Table 3. Mean number of insects collected in sweep net samples Fig. 1. Yellow & purple trap placements adjacent to sweetpotato fields Introduction Sweetpotato (Ipomoea batatas) is a major horticultural crop in the U.S. valued at $309 million annually (Anonymous 2005). Many soil and foliage feeding insects cause economic losses by direct feeding or indirectly reducing quality and yield of sweetpotatoes. Insects such as rootworms (Diabrotica spp.), several species of wireworms and flea beetles, sweetpotato weevil (Cylas formicarius), white grubs (Phyllophaga spp.) and whitefringed beetles (Graphognathus spp.) that feed on storage roots are more damaging to the crop and very difficult to control (Chalfant et al. 1990, Williams 2005). Proper assessment of potential for these insects to cause excessive losses to the crop requires accurate estimates of their field densities. A reliable sampling technique to determine the population density of insects in sweetpotatoes is needed to time and, in some cases, avoid the unnecessary insecticide applications. Yellow pyramid traps and purple band traps have successfully been used to sample Oebalus pugnax (Rashid et al. 2006) and Agrilus planipennis (McCullough 2005). These traps were compared with traditional sweep net sampling in sweetpotato fields. • Results • Three species of click beetles (adult wireworms, mostly Conoderus vespertinus), Cerotoma trifurcata, Lygus lineolaris, Diabrotica undecimpunctata, and several species of tortoise and flea beetles were collected in purple/yellow sticky traps or sweep net samples. • Significantly (P<0.001) more click beetles were collected in purple traps in August than in mid September (Table 1). • Purple traps installed along private farmers’ fields collected significantly (P<0.001) more click beetles than did traps along research field plots (Table 2). • Sweep net samples contained all insect species except C. trifurcata, whereas, click beetles and flea beetles were only collected during the period of 2 July to 6 August (Table 3). • Significantly (P<0.001) more click beetles (Fig. 2) and L. lineolaris (Fig. 3) were collected in purple sticky traps than in yellow traps. • The numbers of tortoise beetles trapped in yellow sticky traps were significantly (P<0.001) greater than those in purple traps (Fig. 4). • The numbers of D. undecimpunctata collected on 17 and 29 August in purple sticky traps were significantly (P<0.001) more than in yellow traps (Fig. 5). • Objectives • To determine the attractiveness of yellow and purple sticky traps to insects in sweetpotato fields. • To compare insect counts from yellow and purple sticky traps with sweep net samples in sweetpotato fields • Conclusions • Monitoring field populations of adult insects can provide estimates of their larval population densities which is the actual damaging stage of majority of sweetpotato insects. • Purple sticky traps may provide growers a viable alternate method to sweep net sampling for insect pests of sweetpotatoes in Mississippi. • Timely insecticide applications can reduce the populations of adult insects thus reducing the larval feeding to sweetpotato roots in a given field. This will minimize the economic damage. Materials and Methods These studies were conducted in Sharkey, Washington and Bolivar Counties in the Mississippi Delta in 2007. Traps: Eight replications of each yellow and purple sticky traps (Fig. 1) were installed adjacent to sweetpotato fields. Traps were checked on 9, 17, 29 August and 14 September. Insect samples were collected and identified. Sweep Net Samples: Four random sweep net samples were taken weekly from each of four different locations from 2 July to 3 September. Each sample consisted of 25 sweeps. References Cited Anonymous. 2005. USDA, Agric. Stat. http://www.nass.usda.gov Chalfant, R. B., R. K Jansson, D. R. Seal and J. M. Schalk. 1990. Ecology and management of sweetpotato insects. Ann. Rev. Entomol. 35:157-180. McCullough, D. G. 2005. Emerald ash borer trap trees: evaluation of stress agents and trap height. Display Pre. Sec: Beh. and Ecol. ESA Ann. Meet. Fort Lauderdale, FL. Rashid, T, D. T. Johnson and J. L. Bernhardt. 2006. Sampling rice stink bug (Hemiptera: Pentatomidae) in and around rice fields Environ. Entomol. 35(1): 102-111. Williams, M.R. 2005. Sweetpotato insect control guide. Pub. 2304. Ext. Ser. MS State Univ. and USDA. Acknowledgement The authors would like to thank Jack Reed (MSU) and Richard Evans (USDA-ARS, BCPRU) for assistance in insect identification. We thank Larry Russell (ASU) for assistance in trap construction and Chris Johnson (USDA-ARS, SIMRU) for help in setting up traps and sweep net sampling. Thanks are also due to James Vogt (USDA-ARS, BCPRU) for providing laboratory space.