The Effect of Agro-Ecological Zones on the Incidence and Distribution of Aphid Vectors of Pepper Veinal Mottle Virus, on Cultivated Pepper (Capsicum Annuum L.) in Nigeria

Abstract

The distribution of aphid vectors of Pepper veinal mottle virus (PVmV) was studied on cultivated pepper between 2003 and 2005 in the major pepper producing areas of the six agro-ecological zones in Nigeria. The aphids were isolated, identified and their transmission ability determined. Population of aphid vectors increased progressively in all the agro-ecological zones from march at the onset of raining season reaching a peak in August and then declining from September at the on set of the dry season. The Humid forest and derived Savanna agro-ecological zones recorded highest mean population of aphids / leaf and types of aphid's species compared with other agro-ecological zones. Six species of aphid, Myzus persicae (Sulzer), Aphis gossipii (Glover), Aphis craccivora (Koch), Aphis spiraecola (Patch), Aphis fabae (blanchard), and Rhopalosiphum maidis (Fitch), were identified on the pepper fields surveyed in all the agro-ecological zones. There was no significant difference in the occurrence of M. persicae, A. gossipii, A. craccivora, and R. maidis while A. spiraecola and A. fabae that varied in occurrence in all the zones. Ability to transmit PVmV to a healthy pepper plants varied in all the identified aphid species but R. maidis was not able to transmit PVmV from infected to a healthy pepper plant. A more sustainable approach to controlling pepper viruses is by targeting the aphid vectors and preventing the vectors from reaching the crops because the aphid vectors which are virus specific are the major means of transmitting virus to healthy plant.

Pepper Veinal Mottle Virus, a Potyvirus of Pepper Under Tropical Conditions

“…They reported that A. spiraecola and A. fabae varied in occurrence in all zones (Table 1). Fajinmi et al (2011) also observed that trapped populations of M. persicae, A. gossypii, A. craccivora, and R. maidis, peaked in a similar sequence across zones and populations of aphid vectors increased in all agro-ecological zones from the onset of the rainy season (March) and then started to decline in September, the onset of the dry season ( Figure 1). Humid agro-ecological zones had the highest populations of aphids and types of aphid species (Table 1) Similarly, Alegbejo (1978Alegbejo ( , 1987 reported that these aphids survive on different hosts during dry and wet seasons and that these plants are important refuges and sources of aphids that damage pepper and transmit PVMV.…”

“…They identified six aphid species that are associated with pepper in the zones: Myzus persicae (Sulzer), Aphis gossypii (Glover), A. craccivora (Fitch). Fajinmi et al (2011) also reported that four species, M. persicae, A. gossypii, A. craccivora, and R. maidis, were consistently dominant across zones, with no significant difference in their occurrence (Table 1). They reported that A. spiraecola and A. fabae varied in occurrence in all zones (Table 1).…”

“…The incidence and distribution of aphid vectors of PVMV on peppers was reported by Fajinmi et al (2011) where aphids were trapped weekly on pepper in agro-ecological zones including humid forest, derived savanna, southern Guinea savanna, mid-altitude, northern Guinea savanna, and Sudan savanna in Nigeria. They identified six aphid species that are associated with pepper in the zones: Myzus persicae (Sulzer), Aphis gossypii (Glover), A. craccivora (Fitch).…”

“…a Means in a column followed by the same letter are not significantly different, P < 0.05, Duncan's multiple range test. Source:Fajinmi et al (2011).…”

“…He concluded that the high PVMV incidence and severity in these agro-ecological zones of the tropics was due to the warm humid climate, with the presence of many secondary host plants for the virus, which contributed a pool for virus multiplication and ease of spread by viruliferous aphid vectors. Climate and vegetation in the different ecological zones of the tropics played a major role in determining the incidence and severity of PVMV infection on pepper in the field (Fajinmi, 2011;Fajinmi et al, 2011).…”