Cotton Leafhopper Research Articles

Assessment of sticky trap parametersviz., colour, height, direction and combination with azadirachtin against cotton leafhopper

ABSTRACT : In the present investigation relative trapping efficiency of various colour sticky traps at four heights; alone and in combination with azadirachtin 10000 ppm @ 2ml/lit. was assessed against cotton leafhopper. Data on trap height revealed superiority of sticky trap erected 15 cm below crop canopy in terms of significantly higher adult leafhopper trapping (716.67/trap) and was comparable with trap along the crop canopy (634.78/trap). These superior treatments were followed by trap installed at 30 cm and 60 cm above the crop canopy with 517.50 and 192.47 leafhoppers /trap, respectively. Use of yellow colour trap was most efficacious with respect to trapping of adult leafhoppers (736.56 leafhoppers/trap) and was followed by combination of yellow and blue colour (498.48 leafhoppers/ trap), whereas, least population was trapped on blue colour traps with 315.10 leafhoppers/trap. Significantly higher catches of leafhopper on trap were evident when used in combination with azadirachtin sprays on crop (353.14/trap) over traps without azadirachtin sprays (274.38/trap). Interaction effect of trap height, colour and azadirachtin on total catches of leafhoppers indicated superiority of yellow sticky trap erected at 15 cm height below crop canopy in combination with azadirachtin spray and was in turn statistically at par with the yellow sticky trap along crop canopy in combination with azadirachtin spray and yellow sticky trap at 15 cm height below crop canopy without azadirachtin spray. Higher efficacy of trap colour and height combination was evident in combination with azadirachtin 10000ppm @ 2ml/lit. spray on crop with yellow sticky trap at 15cm below crop canopy as the most effective in recording minimum population of leafhoppers (2.40 and 3.32 leafhoppers/leaf) over 5.42 and 6.45 leafhoppers/leaf in untreated control at 7 and 14 days after application of azadirachtin. Irrespective of trap colour, height and combination with azadirachtin significantly maximum catches of leafhopper population was recorded on trap in North East direction as compared to South West direction.

Detoxifying enzyme studies on cotton leafhopper, Amrasca biguttula biguttula (Ishida), resistance to neonicotinoid insecticides in field populations in Karnataka, India

AbstractThe cotton leafhopper (Amrasca biguttula biguttula Ishida) is considered to be an alarming insect pest causing both quantitative and qualitative loss in cotton. In situ bioassay studies were done and the role of detoxifying enzymes in conferring resistance to neonicotinoid groups of insecticides in low (MUD), medium (DVG), high (HVR) and very high (GLB) pesticide usage areas of Karnataka were determined. Bioassay studies showed that imidacloprid, thiamethoxam, acetamiprid, thiacloprid and clothianidin registered varying levels of resistance for all the locations studied. The resistance ratio was high in imidacloprid (3.35, 8.57, 9.15 and 12.27 fold respectively) and the lowest in dinoferuran (1.86, 5.13, 6.71 and 9.88 fold respectively). Furthermore, the enzyme activity ratio (glutathione-S-transferase) was relatively greater, and corresponded to the higher LC50values of neonicotinoids for very high, high, medium and low pesticide usage areas. Our study suggested that the higher activity of the detoxifying enzyme in the resistance population of cotton leafhopper apparently has a significant role in endowing resistance to neonicotinoid groups of insecticides. However, this study recommends using neonicotinoids in cotton growing areas with caution.

Diversity of culturable gut bacteria associated with the field populations of cotton leafhopper (Amrasca biguttula biguttula) in India

Field populations of cotton leafhopper [Amrasca biguttula biguttula (Ishida)] exposed to heavy applications of imidacloprid, acephate, acetamiprid and dimethoate were collected from the seven cotton (Gossypium spp ) growing areas of the country. Thirty culturable bacteria were isolated from the guts of 16 populations of leafhoppers and were characterized through morphological and molecular methods. A good diversity of microflora was recorded across the location and is unique with respect to the locations. None of them are repeated except the genera Bacillus and Enterobacter. There was more number of gut microflora associated with the leafhoppers collected from Dharwad where the insecticide usage pattern and the number of sprays were very high as compared to other locations. Various Bacillus spp. were reported in the Dharwad population. The association of Enterococcus asburiae, Enterobacter silesiacus from the guts of leafhoppers of Guntur which was exposed to nine rounds of sprays of acephate, imidacloprid and dimethoate as compared to Bangalore which was not exposed to insecticides at all. Enterococcus hormaechei was isolated from the insects of Bangalore. The predominant bacterial genera identified in A.biguttula biguttula were Serratia, Bacillus, Enterococcus, Enterobacter, Pantoea, Methylobacterium, Stenotrophomonas, Pseudomonas and Paenibacillus.

Impact of neonicotinoid seed treatment of cotton on the cotton leafhopper, Amrasca devastans (Hemiptera: Cicadellidae), and its natural enemies.

Neonicotinoid seed treatments suppress populations of pest insects efficiently and can enhance crop growth, but they may have negative effects on beneficial arthropods. We evaluated the effects of either imidacloprid or thiamethoxam on the abundances of a sucking pest, the cotton leafhopper (Amrasca devastans), and its arthropod predators under field conditions. We also evaluated the impact of seed treatment on transgenic cotton plant growth, with pests and natural enemies present or absent. Imidacloprid and thiamethoxam reduced pest abundance, with greater effects when dosages were higher. Treatment at recommended doses delayed the pest in reaching the economic damage threshold by around 10-15 days (thiamethoxam) and 20 days (imidacloprid). Recommended doses also enhanced plant growth under all tested conditions; growth is affected directly as well as via pest suppression. Neonicotinoid applications reduced abundance of beneficial arthropods, with lower populations after higher doses, but negative effects of imidacloprid were not apparent unless the manufacturer-recommended dose was exceeded. Imidacloprid applied at the recommended dose of 5 g kg(-1) seed is effective against A. devastans and appears to be safer than thiamethoxam for natural enemies, and also enhances plant growth directly. We caution, however, that possible sublethal negative effects on individual beneficial arthropods were not evaluated. © 2015 Society of Chemical Industry.

THE ROLE OF PARASITOIDS AND PREDATORS FOR CONTROLLING COTTON LEAFHOPPER Amrasca biguttula (ISHIDA) (HETEROPTERA: CICCADELIDAE)

Cotton leafhopper, Amrasca biguttula is a serious early-season cotton pest. It sucks plant sap, injects its toxic saliva, and causes hopper burn. Controlling the cotton leafhopper with aerial spray of insecticides causes another problem i.e., increasing population of cotton bollworm, Helicoverpa armigera as its natural enemies are also eliminated. So far, released-national-cotton varieties have been moderately resistant to the leafhopper and will not survive when the pest population is high. The use of systemic insecticide, through seed treatment before planting, could escape the leafhopper damage symptom until 60 days after planting, negatively affects to the development of natural enemies, and long term usages may cause damages to the environment. Indigenous parasitoids and predators can be used for controlling the leafhopper population effectively, efficiently, and environmentally friendly. The predominant parasitoids on cotton plantation are egg parasitoids, Anagrus spp., and predators are spiders, lady bird beetles, and predatory mired bugs. The role of parasitoids and predators could be optimized by increasing their population in the early season. This could be done by addition of their food sources through raising the vegetation diversity, spraying foods for predators and attractant for parasitoids and predators. Intercropping cotton with secondary food crops would increase vegetation diversity, increase predator population, and egg parasitism. It may also suppress the leafhopper population, maintain cotton-seed productivity, and leave out chemical insecticide spray. Key words: Amrasca biguttula, cotton, cotton leaf-hopper, parasitoid, predator.

EVALUATION OF FOUR INTEGRATED PEST MANAGEMENT PACKAGES FOR CONTROLLING MAIN PESTS OF COTTON IN RAINFED FIELDS

Cotton production nationally is low due to various constraints, including pests. Two main pests commonly found in cotton plantation in rain fed fields are cotton leafhopper (Amrasca biguttula) and cotton bollworm (Helicoverpa armigera). The study aimed to evaluate four packages of integrated pest management (IPM) techniques to control cotton leafhopper and cotton bollworm in rain fed fields. The experiment was conducted in farmers’ fields at Asembagus, East Java, between January and July 2012. Four packages of IPM evaluated were cotton varieties, i.e. Kanesia 10 or Kanesia 13, and seed treatment with synthetic insecticide (imidacloprid) before sowing or spraying molasses (10 ml L-1 water) as food for natural enemies. The cotton plants were intercropped with groundnut and sprayed with neem seed extract (NSE) at the action threshold level for pest control. These packages were compared among themselves and also with the methods usually used by farmers, i.e. planting cotton variety Kanesia 8 intercropped with groundnut and pest control using synthetic chemical insecticides. Twenty five plants were sampled randomly per plot and measured for their growth, leafhopper and bollworm populations, as well as cotton seed yield per plot. Observations were made weekly, starting at 30 days after planting (DAP) until 120 DAP. The results showed that the use of Kanesia 10 or Kanesia 13 intercropped with groundnut and spraying molasses to conserve natural enemies was the best pest management practice and superior to farmers’ practices. Conserving natural enemies is not only profitable (saving production cost of IDR1,150,000 to IDR1,500,000 ha-1 season-1), but also safe for the environment (no need to spray chemical insecticides).

EVALUATION OF FOUR INTEGRATED PEST MANAGEMENT PACKAGES FOR CONTROLLING MAIN PESTS OF COTTON IN RAINFED FIELDS

Cotton production nationally is low due to various constraints, including pests. Two main pests commonly found in cotton plantation in rain fed fields are cotton leafhopper (Amrasca biguttula) and cotton bollworm (Helicoverpa armigera). The study aimed to evaluate four packages of integrated pest management (IPM) techniques to control cotton leafhopper and cotton bollworm in rain fed fields. The experiment was conducted in farmers’ fields at Asembagus, East Java, between January and July 2012. Four packages of IPM evaluated were cotton varieties, i.e. Kanesia 10 or Kanesia 13, and seed treatment with synthetic insecticide (imidacloprid) before sowing or spraying molasses (10 ml L-1 water) as food for natural enemies. The cotton plants were intercropped with groundnut and sprayed with neem seed extract (NSE) at the action threshold level for pest control. These packages were compared among themselves and also with the methods usually used by farmers, i.e. planting cotton variety Kanesia 8 intercropped with groundnut and pest control using synthetic chemical insecticides. Twenty five plants were sampled randomly per plot and measured for their growth, leafhopper and bollworm populations, as well as cotton seed yield per plot. Observations were made weekly, starting at 30 days after planting (DAP) until 120 DAP. The results showed that the use of Kanesia 10 or Kanesia 13 intercropped with groundnut and spraying molasses to conserve natural enemies was the best pest management practice and superior to farmers’ practices. Conserving natural enemies is not only profitable (saving production cost of IDR1,150,000 to IDR1,500,000 ha-1 season-1), but also safe for the environment (no need to spray chemical insecticides).

Baseline toxicity of chloronicotinyls against cotton leafhopper, Amrasca biguttula biguttula, and detection of insecticide resistance

The populations of cotton leafhopper, Amrasca biguttula biguttula were collected from two different locations, viz. Coimbatore and Salem, and the identified susceptible Salem population was cultured continuously for four generations without exposure to insecticides and the baseline toxicity data were established by leaf dip bioassay method (IRAC method No. 8). The tentative discriminating doses fixed, based on the susceptible A. biguttula biguttula population, were 1.10, 0.10, 0.02 and 1.0 ppm for imidacloprid, thiamethoxam, acetamiprid and thiacloprid, respectively. Insecticide resistance was then monitored using the above doses against leafhoppers collected from Coimbatore, Bhavanisagar, Salem and Srivilliputhur. The level of resistance in A. biguttula biguttula, as revealed by per cent survival, varied from 6.67 (Salem) to 15.38 (Srivilliiputhur) for imidacloprid; 3.33 (Salem) to 15.09 (Srivilliputhur) for thiamethoxam; 5.00 (Bhavanisagar) to 20.00 (Srivilliputhur) for acetamiprid; and 5.00 (Bhavanisagar) to 9.09 (Srivilliputhur) for thiacloprid.

Molecular and Taxonomic Diversity of Cotton Leafhopper,Amrasca biguttula biguttula(Ishida) in Major Cotton Growing Districts of Karnataka

Cotton leafhopper, Amrasca biguttula biguttula (Ishida) is an alarming pest causing both quantitative and qualitative losses on Bt cotton. Taxonomic identification results revealed that composite sample of adult cotton leafhopper population collected from Dharwad, Belgaum, Haveri, Mysore, Raichur, Yadgir districts was Amrasca biguttula biguttula (Ishida). Fragment of mitochondrial cytochrome oxidase subunit I (COI) gene was amplified and sequenced from the cotton leafhoppers collected from six districts. COI gene sequences of A. biguttula of Belgaum, Haveri and Mysore districts showed 99 per cent similarity with NCBI published sequence of A. biguttula COI gene (HQ113231.1), while those from Raichur and Yadgir districts showed 98 per cent similarity. Population from Dharwad district showed 96 per cent similarity. Sequence analysis showed high similarity among the leafhopper population of major cotton growing districts of Karnataka.

Influence of varied dosages of nitrogen application on the leafhopper population inBtcotton under rainfed condition

Field experiments were carried out to study the influence of nitrogen dosages (0, 25, 50, 75, 100, 125, 150, 175 and 200 kg/ha) on cotton leafhopper population under rainfed condition in Dharwad during 2011–12 and 2012–13. Mean population of leafhopper was highest at higher dosages of nitrogen as compared to recommended and lower dosages of nitrogen. A positive and significant correlation between the insect-pests and nitrogen fertilizer was observed. Leaf nitrogen content increased with the increased nitrogen dosages applied wherein leafhopper population correlated positively and significantly with the leaf nitrogen content. Increased levels of nitrogen from 0 to 125 kg/ha significantly increased production of good opened bolls per plant, total bolls per plant and seed cotton yield. Further increased level of nitrogen from 150 to 200 kg/ha increased leafhopper population and reduced the seed cotton yield.

EVALUATION OF AN IPM MODULE AGAINST THE LEAFHOPPER, AMRASCA DEVASTANS (DISTANT) IN COTTON

To develop an IPM module against cotton leafhopper different tactics like, leafhopper resistant cultivar (KC 2) were integrated in different combinations and were evaluated. When the susceptible LRA 5166 was raised from imidacloprid treated seed with cluster bean intercrop and need based application of dimethoate 0.03 % leafhopper population was reduced by 79.01 per cent and seed cotton yield increased by 31.76 %. The pest reduction was 57.08 % with mere introduction of resistant cultivar viz., KC 2; the yield increase was 58.82 %. The yield increase was 125.88 % when the resistant cultivar KC 2 was raised from imidacloprid treated seeds, grown with cluster bean intercrop and applied with dimethoate on need basis.

Conidial Discharge of an Entomopathogenic Fungus Infecting the Cotton Leafhopper

A laboratory experiment was conducted to determine the conidial discharge of Batkoa amrascae Keller & Villacarlos, an entomopathogenic fungus found infecting the cotton leafhopper on okra. Field and laboratoy-infected leafhopper cadavers were tested for the effect of light. The fungus from field-infected cadavers kept in the dark during sporulation produced and average of 26,372 conidia (29 hr. mean time conidial production), whereas those exposed to light had 5,290 conidia (33 hr. mean time conidial production). On the other hand, laboratory-infected cadavers exposed to light attained an average of 4,447 conidia while that of cadavers kept in the dark had 3,373 conidia, both had 28 hr mean time conidial production.

Oviposition preference of cotton leafhopper in relation to leaf‐vein morphology

Abstract: The oviposition preference of the cotton leafhopper, Amrasca biguttula biguttula (Ishida) was investigated in relation to leaf‐vein characteristics of 12 plant species, namely okra, cotton, castor, pigeonpea, cowpea, cluster bean, green gram, egg plant, sesame, country mallow, portia tree and shoe flower. Observations on the oviposition of the leafhopper under no‐choice conditions were recorded on three occasions during the peak period of leafhopper incidence in the field. On all three occasions the leafhopper rejected green gram, shoe flower and portia tree for egg‐laying, thereby indicating non‐acceptance of these plants for oviposition. For the remaining plants, the number of eggs per leaf differed significantly. Okra received the maximum number of eggs. The lateral veins of castor, cotton, cowpea, egg plant and country mallow leaves received more eggs in comparison with the main vein and subveins whereas in okra the subveins received the highest number of eggs followed by lateral and main veins. The leaves of cluster bean, pigeonpea and sesame were devoid of subveins. In cluster bean and sesame the lateral veins received more eggs than the main vein but in pigeonpea the main vein received more eggs than the lateral veins. Correlations of trichome density and length with the number of eggs laid in different veins were non‐significant. All types of veins in okra leaves were thicker than the rest of the test plants, which might have stimulated more egg laying in okra. The thickness of each category of vein, namely main vein (r=0.60), lateral veins (r=0.65) and subveins (r=0.56) was found to be positively correlated with the number of eggs laid. The length of the main and lateral veins were also found to be positively and significantly related to the number of eggs laid. It can be concluded from the present investigations that leaf‐vein thickness and length are crucial factors in influencing the oviposition behaviour of the cotton leafhopper.

Role of chemical components of resistant and susceptible genotypes of cotton and okra in ovipositional preference of cotton leafhopper

Ovipositional preference of cotton leafhopper,Amrasca biguttula biguttula (Ishida) on resistant and susceptible genotyps of cotton and okra was found under the influence of chemical components. The non-reducing sugars, tannins, silica and free gossypol in the leaves showed significant and negative correlation with the number of leafhopper eggs.

Chemical Control of Cotton Insect Pests in Thailand

Abstract A continuing research programme of chemical control on major cotton pests in Thailand has been conducted since 1960 to discover the most effective insecticides. Before 1978 twelve systemic insecticides for controlling the cotton leafhopper, Amrasca devastans (Dist.), and the cotton aphid, Aphisgossypii Glov., and eight insecticides for controlling the cotton bollworm, Heliothis armigera (Hbn.), were identified and sent for official recommendation. This report gives details of research work carried out during 1978 and 1979, and includes seven new compounds, decamethrin, cypermethrin plus amitraz, sulprofos, profenofos, profenofos plus DDT, thiofanox and thiodicarb RH 0994, for bollworm control. The bollworm resistance to synthetic pyrethroids and the increase in whitefly, Bemisia tabaci (Genn.), after using the synthetic pyrethroids are also discussed.

Interruption of acoustic communication and mating in a leafhopper and a planthopper by aerial sound vibrations picked up by plants

Each sex of the cotton leafhopper and the rice brown planthopper communicates with the opposite sex by certain specific sound vibrations which travel through the plant surface and lead to mating. External sounds of certain frequencies, viz., 200 c/sec, generated by a harmonium or an audio-oscillator are picked up from the air by the plants and interrupt the acoustic communication as well as mating of the insects. Notes with harmonics are effective whereas pure notes are ineffective.

Mating Behavior of the Cotton Leafhopper, Empoasca devastans, in Relation to Its Age, Ovarian Development, Diurnal Cycle, and Co2 Treatment

The mating behavior of Empoasca devastans (Homoptera: Cicadellidae) involves an increase in the locomotor activity of males and a decrease in that of females, approach of males to stationary females, followed by interlocking of their genitalia. Mating activity increases with age, reaching its maximum in 5-day-old individuals, and declines thereafter. This change is due to an increase in the mating receptivity of both males and females up to 5 days after emergence and a subsequent decline in the receptivity of females only. Such a change in the mating receptivity of females is related to the maturation of their ovaries. The mating activity of the insects is not much affected by day-night rhythm. CO2-treatment of the insects delays mating activity for 8-12 hours after revival from anesthesia.