Biological control of insect pests in NE India
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KI Singh and SM Haldhar
The economy of the North Eastern States is mainly rural and agrarian. The region offers scope for cultivation of a wide variety of agricultural crops because of its diversities in topography, altitude and climatic conditions. The major crops grown are rice, sugarcane, potato, wheat, maize, ginger, cardamom, pulses, oilseeds, tea, flowers, fruits and vegetables. There are severe pest problems on several crops grown in this region.
The North Eastern region represents an important biodiversity hotspot, one of the 25 global biodiversity hotspots currently recognized. It is important to preserve this region and help conserve the biodiversity of the region. Pesticide consumption pattern in the region indicates that Assam consumes 0.4 to 0.6 kg ha-1 and Meghalaya 0.3 to 0.4 kg ha-1. Data on the pesticide load in the environment indicate that substantial areas in Assam carry a pesticide loan of 7-10 kg sq. km-1 while in Meghalaya, Nagaland and Manipur it is 1.3 kg sq. km-1.
However, it is encouraging to observe that there has been a reduction in pesticide consumption in the last decade in most of the States. The need of the hour is to search for potential natural enemies of the major pests of the region and we can be sure the search would yield promising results. It would be a folly and also counterproductive to resort to the use of chemical pesticides to check insect pests and diseases in the crops grown in this region, as they would indiscriminately kill the natural enemies along with the pests themselves. Indigenous natural enemies could effectively reduce pest numbers and conservation biological control could form the backbone of IPM for various pests. There is a need to set up mass production units for the production of some biocontrol agents and the opportunity is there for rural youth and women to come forward and set up such units to help the farmers of the region.
Biological control in rice is an important crop occupying about 40 lakh hectares in the North Eastern States. Pesticide usage is minimal in the region on rice. Thus the natural enemy complex in the agro-ecosystems of all these States has not been adversely impacted. Conservation biological control, which is the recommended practice in rice, can easily be adopted in these States. In the case of some pests like the rice yellow stem borer and leaf folder inundation biological control may also have to be adopted. Rice insect pests have had long, close associations with their natural enemies allowing stable relationships to develop. Predator and parasitoid guilds recorded in rice ecosystems belong to ten orders and 57 families of predators and three orders comprising 40 families of parasitoids, indicating the great diversity and richness of the natural enemy community in rice. The interactions of such predators, parasitoids and insect pathogens are the cornerstone of modern integrated pest management programs in rice.
The collective importance of natural enemies to pest population regulation is clearly demonstrated by observing outbreaks of insect pests after the removal of natural enemy communities by a broad-spectrum insecticide. The rice plant can withstand and compensate for over forty percent tiller loss during the early vegetative stage without significant reduction in yield. This gives natural enemies the requisite time to colonize and build up their populations so that they are there in numbers large enough to suppress the pests when they appear.
Conservation biological control in rice is the modification of the environment or habitat in combination with judicious use of pesticides in order to conserve natural enemies and enhance biological control.
Environment management to enhance biological control has proven valuable in many settings and appears to be very important for rice insect pest management. Conservation biological control contains two elements: judicious use of insecticides and modification of the environment. Insecticides are more harmful to natural enemies than to pests.
(To be contd)
The economy of the North Eastern States is mainly rural and agrarian. The region offers scope for cultivation of a wide variety of agricultural crops because of its diversities in topography, altitude and climatic conditions. The major crops grown are rice, sugarcane, potato, wheat, maize, ginger, cardamom, pulses, oilseeds, tea, flowers, fruits and vegetables. There are severe pest problems on several crops grown in this region.
The North Eastern region represents an important biodiversity hotspot, one of the 25 global biodiversity hotspots currently recognized. It is important to preserve this region and help conserve the biodiversity of the region. Pesticide consumption pattern in the region indicates that Assam consumes 0.4 to 0.6 kg ha-1 and Meghalaya 0.3 to 0.4 kg ha-1. Data on the pesticide load in the environment indicate that substantial areas in Assam carry a pesticide loan of 7-10 kg sq. km-1 while in Meghalaya, Nagaland and Manipur it is 1.3 kg sq. km-1.
However, it is encouraging to observe that there has been a reduction in pesticide consumption in the last decade in most of the States. The need of the hour is to search for potential natural enemies of the major pests of the region and we can be sure the search would yield promising results. It would be a folly and also counterproductive to resort to the use of chemical pesticides to check insect pests and diseases in the crops grown in this region, as they would indiscriminately kill the natural enemies along with the pests themselves. Indigenous natural enemies could effectively reduce pest numbers and conservation biological control could form the backbone of IPM for various pests. There is a need to set up mass production units for the production of some biocontrol agents and the opportunity is there for rural youth and women to come forward and set up such units to help the farmers of the region.
Biological control in rice is an important crop occupying about 40 lakh hectares in the North Eastern States. Pesticide usage is minimal in the region on rice. Thus the natural enemy complex in the agro-ecosystems of all these States has not been adversely impacted. Conservation biological control, which is the recommended practice in rice, can easily be adopted in these States. In the case of some pests like the rice yellow stem borer and leaf folder inundation biological control may also have to be adopted. Rice insect pests have had long, close associations with their natural enemies allowing stable relationships to develop. Predator and parasitoid guilds recorded in rice ecosystems belong to ten orders and 57 families of predators and three orders comprising 40 families of parasitoids, indicating the great diversity and richness of the natural enemy community in rice. The interactions of such predators, parasitoids and insect pathogens are the cornerstone of modern integrated pest management programs in rice.
The collective importance of natural enemies to pest population regulation is clearly demonstrated by observing outbreaks of insect pests after the removal of natural enemy communities by a broad-spectrum insecticide. The rice plant can withstand and compensate for over forty percent tiller loss during the early vegetative stage without significant reduction in yield. This gives natural enemies the requisite time to colonize and build up their populations so that they are there in numbers large enough to suppress the pests when they appear.
Conservation biological control in rice is the modification of the environment or habitat in combination with judicious use of pesticides in order to conserve natural enemies and enhance biological control.
Environment management to enhance biological control has proven valuable in many settings and appears to be very important for rice insect pest management. Conservation biological control contains two elements: judicious use of insecticides and modification of the environment. Insecticides are more harmful to natural enemies than to pests.
(To be contd)