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Thrips Species Attacking Lentil Plants Their Population Abundance and Control

M.A. Islam
Department of Entomology, Bangladesh Agricultural University, Mymensingh

M.A. Sardar
Department of Entomology, Bangladesh Agricultural University, Mymensingh

Abstract/ Executive Summary:

Three species of thrips viz. Thrips nigropilosus Uzel or palmi Karny, Scir1othrips (probably dorsalis Hood.) and Megalurothrips usitatus (Bagnall) were recorded in the field infesting lentil plants. The lentil plants sustained a high population of the thrips during maximum flowering and podding period in the month of February. The high yielding genotypes appeared to be more susceptible to thrips attack compared to early maturity and large seeded categories of lentil. Spraying of Zolone, Nogos and Sevin on infested lentil plants showed slight differences in the mortality of thrips at three doses of each insecticide. All these insecticides at lowest dose of 0.025% all might be equally effective for the control of thrips.

Keywords: Thrips species, Lentil, Population, Abundance and Control

Location: Mymensingh

Start Date: 08-01-1995

End Date: 25-03-1996

Program Area:

Commodity: Lentil

Objectives:

to identify thrips species occurring in lentil field and to investigate their population level at genotypes of three categories of lentil and their control measure with insecticides.

Methodology:

The abundance of thrips was investigated into experimental plots of early maturity, high yielding and large seeded genotypes of lentil grown in the Genetics and Plant Breeding Field Laboratory, eight weeks after sowing. The lentil plant lines were considered as sampling unit. There were three replicates per genotype. The estimation of the thrips popuatton in the lentil field was carried out at weekly interval. Three samples were randomly taken per genotype of lentil, and five plants were examined as a sample. The sampling work was carried out in the morning from 9.00 a.m. to 12.00 noon in 21 genotypes under early maturity and high yielding lentil respectively and 20 genotypes under large seeded category.To estimate the damage caused to flowers and pods of lentil plants by thrips, two genotypes under early maturity category were investigated from flowering stage in the field. After completion of podding of the plants, observations were taken on the number of dead flowers and the number of pods formed in each plant. Fifteen plants were examined in each genotype. The infestations of thrips were also observed on the individual plants. In a separate experiment conducted in the field, insecticides Zolone 35 EC, Nogos 100 EC and Sevin 85SP at 0.075, 0.050 and 0.025% active ingredient (AI) were sprayed on the lentil plants infested by thrips at flowering stage. There was a control sprayed with water only. Each treatment had three replicate plants and each replicate included three branches. Three branches from a bushy plant were tied together by thread at the base gently before treatment. Immediately after spraying, the lentil plants were caged with cotton bag fastened to the bamboo stick so the no thrips could escape. The observation was made after 48 hours of application on the dead and alive thrips from branches and inside the cages, and flowers were opened by needle to count the number of thrips if any present inside them.

Source of Information: Bangladesh J. Agril. Sci. 28(1): 53-58, January, 2001

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

Three species of thrips that infested lentil plants in the field these were Thrips nigropilosus Uzel or palmi Karney, Scirtothrips (Probably dorsalis Hood.) and Megalurothrips usitatus (Bagnall). The identified specimens included adult males and females.Thrips occurred mostly in flowers of lentil plants. Sometimes they were found on the leaves. The infestation took place in the field from January to March. The initial population was recorded in January eight weeks after sowing. The total numbers of thrips irrespective of the species were estimated to be 208-327,208-380 and 67-309 per five plants of early maturity, high yielding and large seeded genotypes respectively from January to March. In early maturity genotypes of lentil, the mean number of thrips ranged from 0.3 to 31.0 per five plants in eight sampling occassion. The peak population occurred in third week of February and the number differed significantly (P<0.05) among genotypes. Spraying Zolone, Nogos and Sevin at 0.075, 0.050 and 0.025% active ingredient (AI) killed 85.5-99.0% thrips. Zolone and Sevin resulted 91.9-98.6 and 96.2-99.0% thrips mortality respectively at three doses. The mortality rate of these two insecticides was almost the same. The application of Nogos at three doses produced 85.5- 89.4% mortality. This insecticide killed thrips at lowest rate compared to the rates of killing due to Zolone and Sevin. The death of thrips at three doses of Zolone, Sevin and Nogos did not differ much within the insecticide. Over 80% thrips died at the lowest dose (0.025% AI) of Nogos, and Zolone and Sevin caused death over 90% at this dose. Virtually the effectiveness of the three insecticides in controlling thrips seemed to be the same. These are in practice to control sucking insects, and from this point of view all these insecticides might prove effective against thrips attack to lentil plants.

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