Effect of intercrops on thrips species composition and population abundance on French beans in Kenya

Abstract

The study aimed at determining thrips species composition and thrips population density on French bean planted as a sole crop and as an intercrop with either sunflower, Irish potato, or baby corn, in various combinations. Field experiments were conducted in two seasons to examine: (1) thrips population development and thrips species composition over time, (2) effect of intercrops on thrips population density and natural enemies, and (3) effect of intercrops on French bean yield. The experiments were conducted at the Kenya Agricultural Research Institute, Embu, Kenya in a randomized complete block design with four replicates. The thrips population on French beans increased with time. It showed a peak at the flowering stage then started declining when the crops were nearing senescence. French beans hosted four thrips species, Megalurothrips sjostedti (Trybom), Frankliniella schultzei (Trybom), Frankliniella occidentalis (Pergande), and Hydatothrips aldolfifriderici (Karny) (all Thysanoptera: Thripidae) in order of decreasing abundance. The main thrips species on Irish potato and sunflower was F. schultzei. Baby corn hosted only Frankliniella williamsi (Hood) and Thrips pusillus (Bagnall). A monocrop of French bean hosted more thrips than a French bean intercrop mix. Thrips natural enemies such as Orius spp. and Ceranisus spp. were recorded in all crop plants but in especially high numbers on French bean and baby corn, respectively. Plots with French bean alone had about 1.4 times higher yields compared to intercropped plots of French bean with sunflower and French bean with baby corn. However, the percentage of pods that could get rejected on the market due to thrips damage was highest on plots with French bean alone (68 and 63%) and lowest on plots with French bean and baby corn (35 and 37%) in the first and second seasons, respectively. This study showed that a complex of thrips is found in the field and its composition varies with crop stage and species. Intercropping French bean with other crops compromises on French bean yield but reduces damage to the French bean pods, thereby enhancing marketable yield.

Evaluation of a Push-Pull Strategy for the Management ofFrankliniella bispinosa(Thysanoptera: Thripidae) in Bell Peppers

“…Numerous studies showed that various host plants of Orius, including H. annuus, when used as companion plants resulted in reduced thrips in the main crop (Bottenberg et al 1999, Kasina et al 2006, Ló pez and Shepard 2007, Frantz and Mellinger 2009, Nyasani et al 2012. Coll (1998) in reviewing the scientiÞc literature found that plant diversiÞcation increased Orius species in eight studies, numbers were the same in 11 studies, and numbers were decreased in one study.…”

“…Kasina et al (2006) and Ló pez and Shepard (2007) reported that companion plantings of Tagetes erecta L., Daucus carota L., Coriandrum sativum L., Brassica oleracea L., C. annuum, Zea mays L., and Tanacetum parthenium (L.) Schultz-Bipontinus reduced the numbers of Frankliniella occidentalis Pergande on main crops of Phaseolus vulgaris L. and on species of medicinal plants. Nyasani et al (2012) reported that intercrops of Solanum tuberosum L. and Helianthus annuus L. reduced populations of F. occidentalis and increased populations of Orius spp. in P. vulgaris.…”

On-Farm Evaluation of Homemade Pepper Extract in the Management of Pests of Cabbage,Brassica oleraceaeL., and French Beans,Phaseolus vulgarisL., in Two Agro-Ecological Zones in Ghana

“…Larvae of DBM are capable of causing 20-100 % yield loss on cabbage in Ghana and elsewhere (Chellaiah & Srinivasan, 1986;Lingappa et al 2004;Obeng-Ofori et al 2007). Flower thrips also cause 63-68 % damage to flowers and pod malformation in French beans in the field (Abate 1996;Nderitu et al, 2007;Nyasani et al 2012).…”

Control of Virus Diseases in Maize

“…The "sudden" appearance of emerging diseases can frequently be associated either with the emergence of a vector or with increased vector populations. For example, outbreaks of MCMV in Hawaii and Kenya occurred concurrently with outbreaks of maize thrips ( Jiang, Meinke, Wright, Wilkinson, & Campbell, 1992;Jiang, Wilkinson, & Berry, 1990;Nyasani, Meyh€ ofer, Subramanian, & Poehling, 2012;Wangai et al, 2012). Similarly in Serbia, outbreaks of maize redness, caused by stolbur phytoplasma, occurred simultaneously with dramatically increased populations of a new stolbur vector (Reptalus panzeri L€ ow) that could transmit the pathogen to maize ( Jovic et al, 2009).…”