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Prof. Shashikant. S. Udikeri

University of Agricultural Sciences. Dharwad(India) 


Research Area: Cotton  Pest  Management 


Speech Title:Revision of IPM needs in cotton under Bt transgenic farming and change resilience


Abstract: 

Cotton has insect pest complex which deserve an IPM approach always. Due ti insecticide resistance problem in bolloworms cotton cultivation was difficult and uneconomical in late 80s. Thus, across globe major cotton growing countries have adapted Bt transgenic technology as ultimate resort.  In India, adoption of Bt cotton to contain bollworm menace has seen dramatic increase from 0.038  to 113 m.ha  in fifteen years. Being largest grower of Bt cottons hybrids expressing CryIAc + CryIIAb toxins striking benefits of bollworm suppression ( more than 95%), insecticide usage reduction (60-100%) against bollworms and yield advantage (above 50%) have been harnessed.  The reduction synthetic pyrethroids and organophosphate insecticides after introduction of BG-II Bt cotton hybrids has led enhanced infestation of non-target insect pest species in India and elsewhere. The target pests used to bollworm complex and sucking pests viz.,thrips, leafhoppers, aphids and whiteflies before introduction of Bt cottons. The present day key target pests mealybugs (Phenococcus solenopsis, Paracoccus marginatus),mirid bug Creontiades biserratense, flowerbud maggot Dasineura gossypii. These pests affect fruiting structures and cause more than 60% loss urging for insecticide application atleast twice. Other major problem is neonicotoniod resistance in sucking pests particularly leafhoppers. Imidacloprid resistance is widespread and upto 2000 folds.  Survival of PBW in Bt cottons is also causing an issue. Thus cotton pest management has new targets now which need revised tools in IPM for sustained profit.

The key pests now are shootweevils, leafhoppers, thrips ,miridbugs, flower bud maggots and pink bollworms. Cotton planting pattern is also moving towards high density planting system. Shoot weevils and sucking pests cause 30-45 percent yield loss. Mirid bugs and flowerbud maggots are creating outbreak situation leading upto 70 percent loss independently. Recent studies have shown about 50percent survival of pink bollworms in Bt cottons. Profenphos 50EC and DDVP application has restricted shoot weevil incidence to 5 to 12 percent. Flonicamid application avoided leafhopper and other sucking pest incidence upto 80 percent. Similarly Malathion 50EC emerged as only suiatable chemical for flowerbud maggots. Thus including the best bet technologies against new target pests IPM schedules have been developed and evaluated.  The ideal IPM module  include ; Avoiding seed dressing with neonicotinoids based on resistance, new chemistry for sucking resistance management (flonicamid, pymetrazine), high efficacy bio-molecules like and insect pathogens are essential for  effective management of leafhoppers, thrips. Monitoring of pink bollworm incdeince through phero sensors and management through mass trapping) 20 traps per hectare) or using PB ropel or SPLAT technologies is inevitable. An ETL of 5 bugs per plant and 10 percent twisting of buds has been fixed for insecticide usage against these pests. Location specific management of mites, shoot weevil is also essential. Blue or yellow colored sticky traps at the rate of 25 per hectare found to serve as monitoring tools for mirid bugs and flowerbud maggots. Biotech tools viz., RNAi and host plant resistance are tools to avoid insecticides being used against miridbugs, flowerbud maggots and mealybugs.  Parasitoids and sterile insects also have logical place in revised IPM. The ideal IPM module in HDPS has shown 2.5quintals of yield advantage over sole reliance on insecticides along with 2.6 benefit to cost ratio besides conservation of natural enemies. Concurrently, the issues of insecticide resistance in sap feeding pests particularly leaf hoppers and thrips has to address through IPM. Under climate change integers these issues have to be re-looked for a convenient and profitable alteration in IPM approaches, which could be location specific.


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Prof. Hengjia Zhang

Gansu Agricultural University, China


Research area:  Utilization and Regulation of Regional Soil and Water Resources


Title: Photosynthetic Characteristics of Intercropped Winter Wheat under Limited Supplemental Irrigation in the Semiarid Northwestern China



Abstarct: 

In semiarid environment soil water is the major constraint factor in crop production. A field experiment was conducted for intercropped winter wheat (Triticum aestivum) to evaluate the effects of limited supplemental irrigation on photosynthetic characteristics of intercropped winter wheat. An accurately controlled 35 mm of single drip irrigation was applied at a certain wheat growth period.

Grain yield, CGR, NAR, and SWP in the intercropped wheat plots were all affected by limited supplemental irrigation applied at a certain growth period. Significances occurred in grain yield between the intercropped wheat treatments and sole wheat control (CKW), and significant differences were also found in yield between the irrigated intercropped wheat plots (WC2W, WC3W, WC5W) and not irrigated (WC1W) except for WC4W plots with nearly the same yield as WC1W. In comparison with CKW, 11.8%, 18.5%, 23.6%, 11.5%, and 30.7% of yield increase in the intercropped wheat plots were obtained in WC1W, WC2W, WC3W, WC4W, and WC5W respectively. Compared to the intercropped wheat plots without irrigation, yields in WC2W, WC3W, and WC5W were improved by 5.9%, 10.5%, and 16.9%, respectively.

The dynamics of CGR and NAR in both intercropped (WC1W~WC5W) and solely cropped wheat (CKW) showed a type of “single peak” curves, with both the maximum CGR and NAR occurred during jointing to heading (14/4-6/5) of wheat. Before grain filling of wheat (30/5), CGR and NAR in all the intercropped wheat plots were higher than those in sole wheat, while during grain filling to mature the CGR and NAR were significantly lower in all the intercropped wheat plots than those in CKW. In addition, soil water potential (SWP) fluctuated as a function of the precipitation and limited supplemental irrigation.