Abstract
Studies were conducted on resurgence of brown planthopper, Nilaparvata lugens
(Stål) and its possible management through a survey in six different regions (viz.
Tanore, Rajshahi; Niamatpur, Naogaon; Nachole, Chapai Nawabganj; Sadar,
Dinajpur; Tarash, Sirajgonj and Trishal, Mymensingh) and also conducting a
series of experiments in the net-house of BRRI, field of BAU, Mymensingh and
Tanore, Rajshahi. Farmer's perception of BPH resurgence and its management
was more or less similar in different regions with some exception. About 60%
farmers were able to identify BPH and 40% farmer could identify the pest
problem at the later stage of the infestation when burning symptom was visible
in patches. All the respondent farmers (100%) relayed on the use of insecticide
where the selection of insecticide as well as its application was not proper.
Causes of resurgence through the experiments determine in the form of
resurgence ratio showed that the insecticide acetamiprid, chlorpyrifos,
cypermethrin, deltamethrin, fenvalerate, lambda cyhalothrin, thiamethoxam,
abamectin (1%) + acetamiprid (3%), chlorpyrifos(50%)+ cypermathrin (5%),
thiamethoxam (20%) + emamectin benzoate(10%) were higher resurgence
developing chemicals as compared to imidacloprid, cartap, dinotefuran,
isoprocarb/MIPC, phenthoate, pymetrozine. Isoprocarb/MIPC a commonly
used recommended insecticide was found to have of higher resurgence ratio
when applied at sublethal dose (1.26) and also in the upper spectrum of the rice
plant (1.07). Resurgence ratio was higher with the insecticide treatment at the
egg stage (1.71) and combination of all stages (0.82). High resurgence ratio (0.60)
was evident in the field lacking of natural enemies. Insecticide application using
double nozzle sprayer showed low resurgence ratio (0.50) as compared to the
resurgence developed for single nozzle type sprayer (0.65). Integrated
application of the experimentally developed technologies using line sowing,
balance fertilizer, need based recommended insecticide with proper dose at
economic threshold level in the lower spectrum where BPH remain as crowd
reduced the resurgence ratio to a large extent (0.10). The IPM practices were
sound in respect of management of BPH resurgence successfully and
maintaining biodiversity in rice ecosystem.