Pest status of the leafhopper Empoasca dolichi Paoli on groundnut (Arachis hypogaea L.) in the Zaria area of northern Nigeria

Population studies and tests on the relationship between density and damage were conducted in 1999 to 2001 to determine the pest status of <I>Empoasca dolichi</I> on groundnut (<I>Arachis hypogaea </I>L.) in the Zaria area of northern Nigeria. Analyses showed that <I>Empoasca</I> numbers varied significantly from one year to another, and within each year the numbers of leafhoppers observed at the different growth stages of the plant were significantly different (<I>P</I> = 0.01). There was an inverse and highly significant relationship between the mean kernel yield and the <I>Empoasca </I>damage at the different growth stages of the plant. When natural population densities were plotted against economic injury level (EIL), the densities did not reach the EIL throughout the groundnut growing seasons. The insect was thus not an economic pest on groundnut in Zaria during the period of the study.

Observations on Insect Infestation and Damage in Cowpea (Vigna Unguiculata) Intercropped With Tomato (Lycopersicon Esculentum) in a Rain Forest Area of Nigeria

SUMMARYInsect infestation and damage in cowpea (Vigna unguiculala), planted sole or intercropped with tomato (Lycopersicon esculentum) was monitored in 1987 and 1988 in Akure, Nigeria. Infestation of cowpea byEmpoasca dolichiwas significantly reduced by intercropping with tomato in both years, except in the early season of 1988. Infestation of cowpea byOotheca mutabilis, Aphis craccivora, Megalurothrips sjosledti and Maruca testulaliswas not affected by intercropping with tomato in either year. Damage by pod-sucking bugs and Heliothis armigera was significantly higher in sole cowpea than in cowpea intercropped with tomato, in both years. Sole cowpea had a significantly lower seed yield than cowpea intercropped with tomato.Observaciones en cuanto a la infestación de insectos y daños en el caupí(Vigna unguiculata)sembrado en forma simultánea con tomate(Lycopersicon esculentum)en una zona de bosque tropical en Nigeria

Effect of Weeds on Pre-flowering Insect Infestation and Seed Yield of Cowpea (Vigna unguiculata) in a Rainforest Area of Nigeria

SUMMARYPre-flowering insect infestation of cowpea, Vigna unguiculata, was monitored in weedy and weed-free plots in 1986 and 1987 in Akure, Nigeria. Weediness generally reduced infestations of both the leafhopper, Empoasca dolichi, and the flea beatle, Ootheca mutabilis. However, seed yield was reduced in the weedy plots despite heavier pre-flowering insect populations in the plots kept weed-free.

The effects of Empoasca dolichi Paoli (Hemiptera: Cicadellidae) on the performance and yield of two cowpea cultivars

The effects of feeding by groups of 0, 15, 30, 45, 60, 75 or 90 adults of Empoasca dolichi Paoli per plant on the growth and yield of caged Prima and Ife Brown cowpea plants infested 14, 21 or 28 days after planting were studied in Ibadan, Nigeria. Caging had no significant adverse effects on yield. E. dolichi caused severe hopper-burn in plants infested 14 days after planting. The mean pre-flower-opening stage lasted 42–1, 38–0 and 39–0 days in Prima and 446, 407 and 423 days in Ife Brown plants infested 14, 21 and 28 days after planting, respectively, the first figure for each cultivar being significantly different from the other two. The mean yields were 23 3, 28 5 and 298 pods per plant for Prima, and 350, 48–1 and 437 for Ife Brown, respectively, the first figure for each cultivar being significantly lower than the other two. The reduction in seed yield in damaged plants infested 14 days after planting ranged from 287 to 413% for Prima and 272 to 56–9% for Ife Brown, the reductions being significantly correlated with scores for feeding damage by E. dolichi.

The identity of Empoasca dolichi Paoli (Hemiptera: Cicadellidae) and descriptions of new species of Empoasca from light-traps near crops in Malawi and Nigeria

The identity of Empoasca dolichi Paoli, a serious pest of beans and other crops in Africa, was confused. While processing a collection of leafhoppers from Malawi, E. dolichi was found mixed with other species. The identity of E. dolichi was established with reference to its type material, and two new species and a new subspecies of Empoasca from Malawi and two new species from Nigeria are described. New characters that might help specific identification and show the relationships of groups of species are also illustrated and described.