Ecological Impact of Plant Density and Planting Dates on the Population of Major Pod Sucking Bugs in Relation to Damage and Yield of Improved Pigeonpea Cultivar in Owerri Rainforest Zone, Nigeria

Field experiment was carried out to access the population of three major pod sucking bugs namely
Riptortus dentipes Fab. (Hemiptera: Coreidae), Clavigralla tomentosicollis Stall (Hemiptera:
Coreidae), Anoplocnemis curvipes Fab (Hemiptera: coreidae) and their effect on damage, yield (kg
ha-1) and yield components under varying plant densities and planting dates. The experiment was
conducted at the Postgraduate Teaching and Research Farm, Department of Crop Science and
Technology, Federal University of Technology, Owerri Imo State. Experiment was laid out in a 3 x 4
factorial and treatments comprised of four plant density of 190,474 plants ha-1, 125,000 plants ha-1,
80,000 plants ha-1, 55,556 plants ha-1 and three planting dates, April (early season), July (Midseason),
and October (late season), 2009 and 2010. The results, show that there was significant
(p<0.05) population of the pod sucking bugs on pigeonpea flowers and pods at high plant density and
low on plants at low plant density. There was significant (p<0.05) population of C. tomentosicollis and
A. curvipes in October while April and July planting seasons showed absence of C. tomentosicollis
and A. curvipes The population of R. dentipes occurred throughout the season with peak population in
April which decreased as planting was delayed till October. Also plants at high density recorded high
pod and seed damage resulting in low values of seed yield (147.90 kg ha-1) in 2009, (168.80 kg ha-1)
in 2010 when compared with pigeonpea planted at low density which had low pod and seed damage
with high seed yield of 223.33 kg ha-1 in 2009, and 268.83 kg ha-1 in 2010. Also yield components like
100 pod/seed weight (g), pod/seed yield (g) per plant, number of seeds per pod were low on plants at
high density, but high on plants at low density. July planting season recorded the lowest pest loads,
pods/seed damage, with resultant high pod/seed yield and yield components compared with April and
October planting seasons. Therefore, for high seed yield with minimal damage by pod sucking bugs,
planting the early maturing pigeonpea in July at low density should be incorporated into farming
systems in this zone as integrated Pest Management alternative.