Abundance of the Sugarcane Borer (Lepidoptera: Crambidae) and Foraging Ants (Hymenoptera: Formicidae) in Sugarcane Grown on Organic and Mineral Soils in Florida.

A study was conducted in Florida to determine sugarcane borer, Diatraea saccharalis (F.), injury and infestation levels in sugarcane (Saccharum spp. hybrids), D. saccharalis parasitism rates, and ant foraging activity in 32 commercial fields as affected by soil type (shallow organic vs deep organic vs mineral). In 2017 and 2018, each field was sampled four times during the summer for D. saccharalis by inspecting 100 sugarcane stalks and for foraging ants using plastic tubes baited with hot dog at 12 locations. One non-parasitized D. saccharalis larva was collected in 2017 and in 2018 out of 12,100 and 12,600 stalks sampled, respectively. Additional sampling of 50 stalks per field in October showed that 0.6% (2017) and 0.1% (2018) of the sugarcane stalks had bored internodes, and one Cotesia flavipes (Cameron) (Hymenoptera: Braconidae) cocoon mass was observed. Seven ant species foraged in sugarcane fields, including the red imported fire ant, Solenopsis invicta Buren, which was the most abundant ant. Solenopsis invicta was not affected by soil type; however, sugarcane fields on shallow organic soils might represent a more suitable environment. The third most abundant foraging ant, Nylanderia bourbonica (Forel), was more abundant in mineral soil fields than in shallow and deep organic soil fields. Results suggest that D. saccharalis population levels in Florida sugarcane are extremely low under current production conditions regardless of soil type. In addition, the observation of C. flavipes, S. invicta, and six other ant species suggest that biological control contributes to these low D. saccharalis population levels.

Relative Abundance of the Stink Bug (Hemiptera: Pentatomidae) Complex Infesting Rice in the Everglades Agricultural Area of Florida.

Florida's rice stink bug complex comprises three species; Oebalus pugnax (F.), O. insularis (Stal), and O. ypsilongriseus (DeGeer), the latter two of which are invasive and exclusive to Florida within the United States. A series of surveys were conducted in 2017 and 2018 to determine the relative abundance of the three species throughout Florida's rice growing region within the Everglades Agricultural Area, in addition to comparing their seasonality within crop and noncrop habitats. Sampling occurred in commercial rice fields and adjacent transects of graminaceous noncrop hosts using sweep nets. Oebalus pugnax (52.7%) and O. insularis (61.7%) were the most abundant species in 2017 and 2018, respectively. Both species were more prevalent in rice fields compared to transects of noncrop hosts. Oebalus ypsilongriseus remained in low abundance relative to O. pugnax and O. insularis, and did not differ in numbers collected among rice and noncrop hosts. Of the noncrop hosts in transects, Panicum dichotomiflorum (fall panicum) was the most abundant across both years. This study is the first report of Oebalus species feeding on Echinochloa crus-galli (common barnyardgrass) in Florida. This study shows that the invasive O. insularis continues to increase in abundance, and has surpassed O. pugnax in terms of regional populations. These results emphasize the need for additional studies to assess the interactions among O. insularis and other Oebalus species in addition to its feeding behavior in Florida rice.

The Sugarcane Borer (Lepidoptera: Crambidae) Infests Rice at Low Population Levels in Florida.

The sugarcane borer, Diatraea saccharalis (F.), rice stalk borer, Chilo plejadellus Zincken, and Mexican rice borer, Eoreuma loftini (Dyar), are stem borers (Lepidoptera: Crambidae) that infest rice (Oryza sativa L.) in the southern United States. A 2-yr study was conducted to determine stem borer injury, infestation, and parasitism levels in Florida. Thirty commercial rice fields were selected during the 2017 and 2018 growing seasons throughout the rice production region in southern Florida. Sampling for stem borer injury and infestations was conducted in each field between the milk and early maturation stages by observing plants at 10 locations, with three 1-m2 quadrats per location. In addition, monitoring for E. loftini adults was conducted using one pheromone trap adjacent to each field. In 2017, the number of rice tillers exhibiting stem borer injury averaged 0.024 tillers/m2 and infestation levels averaged 0.008 stem borers/m2, with only D. saccharalis being observed. In 2018, injury and infestation levels averaged 0.062 injured tillers/m2 and 0.023 D. saccharalis larvae or pupae/m2, respectively. The solitary parasitoid Alabagrus stigma Brullé (Hymenoptera: Braconidae) parasitized 33 and 40% of the collected D. saccharalis in 2017 and 2018, respectively. In addition, pheromone traps did not capture E. loftini adults. This study shows that D. saccharalis infests rice in Florida but at relatively low levels not threatening production and that rice fields are habitats for D. saccharalis parasitoids. This study also suggests that C. plejadellus and E. loftini do not occur in southern Florida.

A Relative Resistance Ratio for Evaluation of Mexican Rice Borer (Lepidoptera: Crambidae) Susceptibility Among Sugarcane Cultivars.

The Mexican rice borer, Eoreuma loftini (Dyar), is a major pest of sugarcane (hybrids of Saccharum spp.) in Louisiana and Texas. Resistance to E. loftini was evaluated in 51 commercial and experimental cultivars of sugarcane, energycane (hybrids of Saccharum spp.), and sorghum [Sorghum bicolor (L.) Moench and hybrids of Sorghum spp.] in four replicated small plot field experiments from 2009 to 2012. A relative resistance ratio was developed to compare levels of susceptibility among cultivars based on the percentage of bored internodes and survival to adulthood. This index was able to separate cultivars into five resistance categories and provides a new method for comparing levels of resistance among cultivars. E. loftini pest pressure in 2009 was among the highest recorded with injury ranging from 55 to 88% bored internodes. Commercial sugarcane cultivar HoCP 85-845 was identified as resistant in three of four experiments, whereas HoCP 04-838 was identified as susceptible in all experiments. Of the five sugarcane cultivars in commercial production in the Rio Grande Valley of Texas, only TCP 87-3388 was categorized as resistant. Of the cultivars with potential for bioenergy production, all of the energycane cultivars demonstrated higher levels of resistance than high-biomass and sweet sorghum cultivars. Continued evaluation of cultivar resistance to E. loftini is important to development of effective integrated pest management strategies for this pest.