Spatial and temporal incidence of insect pests in farmers’ cabbage fields in Senegal

Abstract

In Senegal, damage caused by insect pests is a major obstacle to seasonal stability and an increase in cabbage production. Little is known about the spatial and temporal distribution of cabbage pests, which makes the design of management recommendations to small-scale farmers challenging. The objectives of this study were to: (i) evaluate the status of insect pests observed in cabbage farmers’ fields; (ii) give information on the spatial and temporal distribution of key pests and (iii) assess the effect of temperature, insecticide applications, and host crop abundance on their incidence. A total of 116 cabbage fields were monitored for insect pests and related damage over four crop cycles, from October 2012 to May 2014, in the main vegetable producing area of Senegal (Niayes). The diamondback moth Plutella xylostella (L.) was by far the most important pest present in all the fields and with high levels of incidence (37.1% infested plants), particularly in the latter part of the dry season in the South of Niayes (50% infested plants). The cabbage webworm Hellula undalis (F.) was mainly observed in the early dry season in the south of Niayes, with an incidence of up to 12.5% infested plants. More surprising was the detection of the tomato fruit worm Helicoverpa armigera (Hübner), with damage of up to 9.4% of cabbage heads. The incidence of sucking pests such as whiteflies Bemisia tabaci (Gennadius), or aphids (including Lipaphis pseudobrassicae (Davis, 1914), Myzus persicae (Sulzer) or Brevicoryne brassicae (L.)) was generally low. The incidence of P. xylostella increased significantly with the number of insecticide applications, indicating that control deployed by growers was ineffective. The incidence of H. undalis did not depend on the number of insecticide applications, but significantly increased with host crop abundance and decreased with temperature. This study is a first step towards developing alternative pest management strategies in the framework of sustainable vegetable production systems.

Species Composition of Thrips (Thysanoptera: Thripidae) in Strawberry High Tunnels in Denmark

“…The highest thrips densities were found in the middle of tunnels. Similar observations have been made of the diamondback moth and the cabbage webworm in different crops [ 73 , 74 ]. The slope at the study site may have caused the middle of the tunnels to be warmer than the area by the tunnel openings due to the upwards wind, a factor which possibly also contributed to a higher number of thrips in the centre of the tunnels.…”

A Generalist Feeding on Brassicaceae: It Does Not Get Any Better with Selection

“…Cabbage ( B. oleracea var. capitata ) is a widely recorded host [ 15 ], and larvae of this insect are considered a pest on these crops, particularly in the subcontinent [ 17 , 18 , 19 , 20 , 21 ] and elsewhere [ 22 ]. Thakor and Patel [ 23 ] readily reared H. armigera on cabbage in the laboratory.…”

Action threshold development in cabbage pest management using synthetic and botanical insecticides

“…The major pests in the current study have been identified as a significant threat to cruciferous crops in many countries (Yankanchi & Patil 2009;Reddy 2011;Labou et al 2017;Shah et al 2019) and insecticides, due to their rapid action, have been the most adopted control measure among growers, despite increasing realization of their undesired effects. IPM considers strategies that can limit or replace excessive reliance on pesticides in order to diminish negative effects while maintaining or improving pest control.…”