priciples of insecticide use in rice ipm

Insecticides in Rice IPM (DRR)
are to be cautioned regarding the possible upsurge of leaf folder following the granular application
against gall midge.
Of late, neonicotinoid insecticides like imidacloprid, thiamethoxam and clothianidin are extensively used
against BPH in endemic areas. In these conditions also there are observations of high leaf folder incidence
compared to untreated plots. Even, if a quick conclusion need not be arrived at that all neonicotinoids
cause resurgence of leaf folder, the situation demands more observations confirming the ineffectiveness
of neonicotinoids against leaf folder, on the part of the rice entomologists and caution for rice farmers.
COMBINATION PRODUCTS: THE SCOPE AND RISK
The latest groups of insecticides like neonicotinoids, diamide compounds like flubendiamide, oxadiazines
like indoxacarb and fermentation products like spinosad and relatively older molecules like synthetic
pyrethroids are effective at low dosages (10 to 100 g a.i./ha) compared to 500 g a.i./ha in case of OPs
and carbamates. But these tend to be more specific. For instance, neonicotinoids are effective against
homopterans or sucking pests while other groups are effective against lepidopterans. Therefore, by
preparing the combination products with one molecule of neonicotinoids and another molecule from
lepidopteran effective groups, it is possible to effectively check the whole pest spectrum attacking rice
crop. Accordingly, the thrust is to evaluate and select suitable combination products for each pest situation
depending on the spectrum of toxicity of these individual compounds. Thus, there is ample scope in this
direction for management of insect pests in general and rice pests in particular. Some of the latest
combination products under evaluation along with their effectiveness against different rice pests are
presented. (Table 3&4).
However, the risk involved with combination products is high toxicity to natural enemies viz., both predators
and parasitoids. At times, the combination products may be aimed at lepidopterans but they may cause
harm to predators of leaf and planthoppers. Hence, a thorough evaluation of these combination products
against the whole complex of natural enemies is essential before recommendation.
Combining insecticides with other methods
Insecticides alone are not the panacea for pest management in rice like any other agro-ecosystem.
Insecticide use should be suitably integrated with other methods like natural enemies, sex pheromones,
resistant varieties, cultural methods etc.
AWARENESS OF TOTALITY OF RICE CROP AS AN ECOSYSTEM
The awareness and the consciousness that rice crop or for that matter any other crop as an ecosystem is
and should be the prime guiding principle whenever some interference with any of the methods of pest
management including insecticide use is decided. For instance, when leaf mite and /or panicle mite are
the problems in an area, then application of acaricides like dicofol, diafenthiuron, abamectin, milbemectin
etc is very much essential. Similarly, when the diseases like sheath blight or sheath rot are prevalent
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