Abstract
Experiments were carried out at El-Riad district, Kafr El-Sheikh Governorate during two successive growing seasons (2015 and 2016) to study the survey and population fluctuations of arthropod pests, insect predators and spiders in sweet potato, Ipomoea batatas (L.) (Apis Cultivar). The investigation revealed the presence of 26 Arthropods; 16 as pests and 10 as predators. Bemisia tabaci Genn.,(Hemiptera: Aleyrodidae) was the most occurring (41.51 & 45.37%) followed by Tetranychus sp., (Acarina: Tetranychidae) (18.74 and 15.39%), Empoasca spp., (Hemiptera: Cicadellidae) (13.24 & 14.15%), Agrius convolvuli (L.), (Lepidoptera: Sphingidae) (7.12 & 6.18%), Nezara viridula (L), (Hemiptera: Pentatomidae) (6.90 & 6.09%) and Eysarcoris ventralis (Westwood), (Hemiptera: Pentatomidae) (6.27 & 5.66 %), in 2015 and 2016 season, respectively. The insect pests; Scantius aegyptius (L.), Gryllus domesticus L., (Orthoptera: Gryllidae) and Aiolopus strepens (Latreille), ( Orthoptera: Acrididae) exhibited the least population densities. Spiders were the most occurring predators (49.30 & 43.27%) followed by coccinellids (34.43 & 32.66%) and Chrysoperla carnea Steph., (Neuroptera: Chrysopidae) (11.36 & 11.80%), in 2015 and 2016 season, respectively), the lowest predatory densities were those of Eupeodes corollae (F.), (Diptera: Syrphidae) (0.95 & 0.81%) in 2015 and 2016 season, respectively. The surveyed spiders by different sampling techniques were found belonging to 13 families; Araneidae, Clubionidae, Dictynidae , Dysderidae, Eutichuridae, Gnaphosidae, Linyphiidae, Lycosidae, Philodromidae, Salticidae, Tetragnathidae, Theridiidae and Thomisidae, with araneid and lycosid being the most abundant. Pitfall traps proved to Coccinella undecimpunctata L. be the most efficient in collecting spiders, followed by sweep net, and hand catch. Predators were detected on sweet potato plants by mid or late June. The population density of Stethorus gilvifrons (Mulsant) was quite low and then increased gradually to exhibit its peak by the first week of August while, C. carnea adults peaked by the first week of September. The peak of C. undecimpunctata adult occurred on June 23 rd. Spiders recorded peaks by late June in 2015 and late July in 2016.
Highlights
Sweet potato, Ipomoea batatas (L.) is an important starchy food crop, especially in developing countries, where it ranks third in value of production and fifth in calorie contribution to human diets, and constitutes one of the seven most important crops on a worldwide basis (Jones 1970, Chalfant, et al 1990, Jansson and Raman 1991 and FAO 2015)
The sweet potato are used as a raw material for the production of starch, alcohol, pectin etc. and the surplus as well as culled tubers can be used fresh or dehydrated in rations for livestock
Sweet potato green vine is an important source of green fodder
Summary
Ipomoea batatas (L.) is an important starchy food crop, especially in developing countries, where it ranks third in value of production and fifth in calorie contribution to human diets, and constitutes one of the seven most important crops on a worldwide basis (Jones 1970, Chalfant, et al 1990, Jansson and Raman 1991 and FAO 2015). In terms of production and nutrition, sweet potato is important to subsistence farmers in developing tropical countries (DeVries, et al 1967, Hahn, et al 1984). Numerous insect species including various members of Lepidoptera, Thysanoptera, Orthoptera, and Hemiptera and spider mites have been recorded as pests of sweet potato (Wyniger 1962, Kay 1973, Chalfant, et al 1990, Amies, et al, 1996, Ekman and Lovatt, 2015). Importance of pest species varies from region to region, some weevils constitute the most important insect threat on a worldwide basis
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