Thrips Megalurothrips Sjostedti Trybom Research Articles

Effects of planting date, cultivar and insecticide spray application for the management of insect pests of cowpea in northern Ghana

Insect pests are a major constraint to cowpea production in northern Ghana where it is widely cultivated. Field experiments were conducted to evaluate the effects of planting date, cultivar and insecticide applications for the management of major insect pests attacking cowpea. There were 4 planting dates, 6 cowpea cultivars of medium maturity periods and 2 insecticide spraying regimes. Data were collected on densities of the major insect pests, including the legume pod borer Maruca vitrata F., thrips Megalurothrips sjostedti Trybom, and the pod-sucking bug complex dominated by Clavigalla tomentosicollis Stal., and grain yield. Early planting of cowpea in mid- or late July resulted in the lowest pest densities compared with those planted at later dates. Two of the six cowpea varieties (IT99-573-2-1 and IT99-573-1-1) supported the lowest numbers of insects across planting dates and irrespective of insecticide spraying regime. However, insecticide sprays significantly lowered pest densities and improved yields in all varieties, and yields were the highest when treatments were combined with early planting in mid-July. The results suggest that for maximum yield, cowpea in the study area should be planted in mid-to-late July and sprayed with insecticide. Where available, these treatments can also be integrated with varieties such as IT99K-573-2-1 and IT99k-573-1-1 which appeared to be less susceptible to insects in the current study.

Efficacy of some insecticides against Thrips, Megalurothrips sjostedti Trybom cowpea crop ecosystem

The study was conducted to determine efficacy of insecticides against Thrips, Megalurothrips sjostedti Trybom on cowpea grown at field experiments were conducted at Breeder Seed Production Centre, Govind Ballabh Pant University of Agriculture and Technology, Pantnagar 2014.The most effective treatment for the control of thrips Megalurothrips sjostedti Trybom was seed treatment with fipronil @ 3 ml/kg + spray with fipronil @ 5 ml/lt with maximum reduction (70.06%) in the thrips population of cowpea while lowest effective treatment for the control of thrips Megalurothrips sjostedti Trybom was seed treatment with imidacloprid 17.8SL @ 10ml/kg + spray with monocrotophos 36SL @ 2ml/lt with minimum reduction (16.02%) in the thrips, Megalurothrips sjostedti Trybom population of cowpea crop.

Farmers' knowledge and perception of grain legume pests and their management in the Eastern province of Kenya

Grain legumes play an important role in community livelihood and in the national economy in Kenya. Unfortunately, in many African countries, production doesn't satisfy the demand in grains due to various constrains. Understanding farmers practices and behavior in the management of grain legume pests is a crucial step in the development of sustainable management strategies. A total of 216 farmers were surveyed in eight districts of eastern Kenya to evaluate farmers' knowledge and perceptions of grain legume pests; to examine current pest management practices, and to identify other production constraints. Grain legumes are grown by a wide age-group of farmers, with both genders equally represented. Chemical control remains the main pest management strategy, and, to ensure pesticide effectiveness, farmers also use increased application rates, chemical alternation, frequent application and mixtures of chemicals. While farmers used other control measures, they showed only limited interest in biological control. The majority of the farmers had experience in grain legume farming and were able to identify the major pests, which were the legume flower thrips Megalurothrips sjostedti Trybom, the cowpea aphid Aphis craccivora Koch and the legume pod borer Maruca vitrata Fabricius. Our survey revealed that education and proximity to extension services contributed significantly to farmers' knowledge of grain legume pests, suggesting the need to provide continuous training and capacity building on integrated pest management in grain legume farming. The study also suggests integration of other pest management strategies such as the use of early maturing varieties, biopesticides and biofertilizer to reduce the use of chemical for sustainable pest management.

Diurnal population trends of Megalurothrips sjostedti and Frankliniella occidentalis (Thysanoptera: Thripidae) and their natural enemies on French bean Phaseolus vulgaris (Fabaceae)

A field experiment was conducted to track the daily population trends and occurrence of the flower thrips Megalurothrips sjostedti Trybom and Frankliniella occidentalis (Pergande), and their indigenous natural enemies Orius spp. and Ceranisus menes (Walker), infesting French beans. French beans in monocrop or interplanted with six companion crops ( Zea mays L., Coriandrum sativum L., Tagetes erecta L., Brassica oleracea var. acephala L., Daucus carota L. and Capsicum annuum L.), and two chemical insecticides, methiocarb (Mesurol 500SC) and L-cyhalothrin (Karate 1.75% EC), were evaluated for their effects on the abundance of flower thrips, throughout the day, at 1-h intervals. The average population peak of thrips was found to occur at around 1300 h, but each species had different peak periods. Adult F. occidentalis populations peaked at midday and adult M. sjostedti populations at 1500 h, while the larvae of the two thrips species peaked at around 1300 h. Orius spp. were the most abundant natural enemies and their populations peaked at around 1400 h. Ceranisus menes population also peaked at around 1400 h.

Effect of host plant resistance in some cowpea ( Vigna unguiculata {L.} Walp.) cultivars on growth and developmental parameters of the flower bud thrips, Megalurothrips sjostedti (Trybom)

The effect of host plant resistance on growth and developmental parameters of the bean flower thrips Megalurothrips sjostedti Trybom was determined on nine cowpea ( Vigna unguiculata {L.}Walp.) cultivars under laboratory conditions. Newly emerged adults M. sjostedti were confined on peduncles with floral buds of the different cowpea cultivars. M. sjostedti suffered 100% pre-imaginal mortality on cowpea lines Moussa local, TVu1509, TVx3236, Sewe and Sanzibanili. Antibiosis is believed to be the mechanism of resistance operating in these cultivars. On KVx404-8-1, M. sjostedti had a prolonged developmental period though not significantly different from Vita 7, the susceptible check at P<0.01. IT91K-180 supported the development and survival of M. sjostedti with the suitability index (growth index) not significantly different from the susceptible check (Vita 7) at P<0.01. Hence the mechanism of its resistance is tolerance.

Cowpea insect damage as influenced by the presence of weeds

The influence of weeds on insect damage of cowpea was studied using 4 weeding treatments in the late seasons of 1981 and 1982 and 5 treatments in the late season of 1986, with one treatment isolating the direct effects of weeds on the grain yield of the crops. Seventeen weed species were identified in the cowpea plots. The results of the study showed that the population of flower thrips Megalurothrips sjostedti Trybom and hemipterous pests increased significantly ( P < 0.05) in the presence of weeds. The effects of weeding frequency on pod damage by the pod-borers, Maruca restulalis Geyer and Cydia ptychora Meyr were not consistent but the presence of weeds seemed to have increased the population of these pests. In the 1981 and 1982 experiments, there were positive correlations between the number of times of weeding and insect damage on seed ( r = 0.85 P < 0.05; r = 0.99 P < 0.01, respectively). In 1986, the results showed a positive correlation between number of undamaged seeds per pod and mean grain yield ( r=0.92 P < 0.01). The presence of weeds was therefore thought to have increased insect damage which led to a yield reduction of about 20% in cowpea.