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Cooperative Extension Service |
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Agricultural
Experiment Station |
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Aquaculture
Dale Bumpers College
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Insect Management
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Adult |
Nymph
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Distribution
Common in North America east of the Rocky Mountains as far north as southern Minnesota and New York. Found in the northern Gulf Coast of Mexico and possibly in the West Indies.
Life Cycle
Adults overwinter in accumulated leaf litter, clumps of grass, or in other sheltered places. In AR emergence from overwintering sites occurs in late April and early to mid May. A series of cultivated and wild host plants are used during the season and are critical to survival and population increases. Cultivated hosts are heading wheat, oats, rye, barley early in the season and grain sorghum (milo) and rice later in the season. Grasses (weeds/wild hosts) are essential to rice stink bug survival. The list of host plants is long but includes barnyardgrass, bearded sprangletop, dallisgrass (Paspalum sp.), vasey grass (Paspalum sp.), lovegrass (Eragrostissp.), ryegrass (Loliumsp.), crabgrass (Digitariasp.), broadleaf signalgrass, Panicum spp., Johnson grass, and others. However, females do not place eggs in all cultivated and wild host plants. Longevity (life span) and fecundity (number of eggs) is influenced by the host plants of nymphs and adults. The number of generations each year is estimated to be 4.
Eggs hatch in about 4 days and the nymphs remain clustered around the egg shells. The first instar ingests only water. The 2nd through the 5th instar nymphs feed primarily on seeds. Total time spend as a nymph is between 15 and 28 days. After becoming an adult, females start depositing eggs in about 3 to 4 days. Adult longevity has been observed to average about 50 days. Adults remain active in host plants until a host becomes senescent or cool weather arrives.
Damage and Symptoms
Adults and nymphs have piercing-sucking mouthparts. Entry of the stylets (mouthparts for feeding) is facilitated by a salivary secretion which hardens on contact with air and remains attached to the rice grain. It is called a feeding sheath. The feeding sheath is the only external evidence that feeding by rice stink bugs has occurred on a grain. Rice stink bugs can successfully feed on kernels from shortly after fertilization until the kernel is in the soft dough stage. The stage of kernel development when fed upon determines the amount and type of damage. Attack during the early stages stops any further development of the kernel (a yield loss). Attack during kernel fill stages removes a portion or all of the kernel contents (also a yield loss); but pathogens are mediated (vectored) into the kernel by the rice stink bug. Infection by pathogens (bacteria or fungi) as well as enzymes produced by the rice stink bug cause discoloration of the kernel (a quality loss plus breakage loss). The rice industry and grain inspection services group all discolored kernels into a category called "pecky rice". Thus, rice stink bugs cause yield losses and quality losses.
Scouting and Treatment Thresholds
Rice fields should be scouted weekly or twice weekly beginning at 75% panicle emergence and continued for 4 weeks. Avoid scouting from mid-day through late afternoon. Useal5inchdiametersweep net to sample for rice stink bugs. At each sample site, make 1 0 consecutive 1800 sweeps to the front and sides while walking forward and swinging the net from side to side. Hold the net so that the lower half of the net is drawn through the foliage and panicles. Count the number of adults and large nymphs after each 1 0 sweep sample. Repeat samples at several random sites (6 or more). Avoid samples at field margins. Calculate the average number of rice stink bugs per 1 0 sweeps. Apply insecticide if infestation is 5 or more rice stink bugs per 10 sweeps during the first two weeks after heading; or if 1 0 or more per 1 0 sweeps is found during the third and fourth week after heading. If the number of bugs is only slightly below the threshold level or if the field is very large, increase the number of samples to improve confidence in sample estimates. Samples taken during the morning hours of 8 to 1 1 a.m. will improve estimates of rice stink bugs.
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University of Arkansas • Division of Agriculture |
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