Parasitism of Stem Borers (Lepidoptera: Pyralidae) Associated with Corn and Sorghum in the Lower Rio Grande Valley of Texas

Use of ablated stalks to assess field rates of parasitism ofDiatraea saccharalis(Lepidoptera: Crambidae) byCotesia flavipes(Hymenoptera: Braconidae)

“…The ablated stalk technique using corn stalks is likely most appropriate for parasites utilizing the ingress-and-sting strategy, such as C. flavipes, so long as the tunnel created by the stalkborer larva remains traversable. The hypothesis that a parasite's foraging strategy will determine the utility of the ablated stalk technique for estimating parasitization is supported by the report of Youm et al (1990). They used a similar technique, placing ablated sugarcane stalks infested with D. saccharalis and Eoreuma loftini (Dyar) larvae in corn and grain sorghum fields to survey for native parasitoids and detect parasitization by exotic parasitoids that were being routinely released.…”

“…Our technique differed from that of Youm et al (1990); in that study, a sugarcane (Saccharum officinarum L.) plant stem was cut, and the cut end was inserted into a 2.5-cm diameter glass vial, containing an individual D. saccharalis larva. They did not report details of plant age, how long the larvae had tunneled into the stem, how the stalks were deployed in the field, or how dry the stalks were.…”

“…A different technique, in which ablated plant stalks are placed in the field for sampling parasites of stalkborers, was tested in the lower Rio Grande Valley (Youm et al 1990). However, the report by Youm et al (1990) did not include details necessary to allow replicating the technique in the field, and sampled for a guild of parasites that probe with long ovipositors, called a probe-and-sting parasite guild .…”

“…However, the report by Youm et al (1990) did not include details necessary to allow replicating the technique in the field, and sampled for a guild of parasites that probe with long ovipositors, called a probe-and-sting parasite guild . We evaluated this ablated-stalk technique by placing ablated sections of corn stalks infested with larvae of the sugarcane borer, Diatraea saccharalis F. (Lepidoptera: Pyralidae), in a corn field to assess parasitization by the introduced parasite, Cotesia flavipes (Hymenoptera: Braconidae).…”

Effect of Planting Date and Density on Insect Pests of Sweet Sorghum Grown for Biofuel in Southern Florida

“…Insect feeding on sweet sorghum has been documented by several workers over the last 30 years (Brewbaker 1975;Duncan & Gardner 1984;Youm et al 1990;Rebe et al 2004), but prior to the research described below begun in 2010 the most recent work in Florida had been conducted by Anderson & Cherry (1983). Following the suggestion by Cartwright (2008) that increased biofuel production may result in the need for increased pest control in such crops, we conducted field trials at 3 planting dates to identify potential arthropod pests on 18 sweet sorghum cultivars with promising yields for southern Florida.…”