Abstract
Time of emergence from overwintering and abundance of sorghum midge, Stenodiplosis sorghicola (Coquillett), that initiate the first spring generation dictate the seasonal abundance and subsequent severity of damage the insect causes later in the growing season to sorghum, Sorghum bicolor (L.) Moench. Prediction models of sorghum midge overwintering emergence would be more accurate if effects of moisture and information on rate of survival of overwintering sorghum midges in relation to crop residue destruction treatments were included. An average of 170 sorghum midges, equivalent to 80,408 per ha, emerged between 1 1 April and 19 June 1995 from nonsheltered, sheltered (no water), sheltered (water added) soil moisture treatments. Peak emergence occurred on 3 May. Among treatments there were no significant differences (F = 0.22, P = 0.81) in the number of sorghum midges to emerge from overwintering diapause because efforts to keep dry the soil under the sheltered treatments failed when rainfall totals > 1.27 cm. However, @9-12 d following a rainfall event of >-1.27 cm, a greater than normal amount of sorghum midges emerged, The number of sorghum midge larvae estimated to have entered diapause per square meter of soil was 1,324. There were no significant differences in numbers of sorghum midges (mean of 2.1) in the top, middle, and bottom thirds of panicies. Percent overwintering survival of sorghum midges was more than twice as high from sorghum residue shredded and disked, 0.87%, than from residue shredded, disked, and deep-plowed treatment, 0.39%. Percent survival in the shredded only treatment, 0.56%, was intermediate to the others. Percent overwintering survival was x 1 00-fold greater for sorghum midges in a greenhouse (88%) than for sorghum midges that overwintered in shredded and disked sorghum residue in a field (0.87%). Percent overwintering survival was 6% for sorghum midges to emerge from panicies placed in a field in late winter.
Mott, Dale Allen (1995). Overwintering survival and role of moisture in diapause termination and subsequent emergence of sorghum midge, (Diptera: Cecidomyiidae). Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -M68.