M. O. Way

Insect pest management in rice in the United States.

Rice is grown in the United States in varied locations where local environmental conditions impact cultural practices and insect diversity and abundance. Each location harbors a unique complex of insect pests which attack rice from seeding to harvest. However, the key insect pests are the rice water weevil (Lissorhoptrus oryzophilus), distributed throughout the rice growing areas of the United States, and the rice stink bug (Oebalus pugax), found only in the southern rice producing states. Insecticides are the main tactics of control but research is underway to develop alternative methods. Economic thresholds have been developed for these and other pests but research continues to refine the damage/insect density relationships in light of new high yielding varieties, associated cultural practices, and complex government subsidy programs. Entomologists must cooperate with researchers in other disciplines to solve these complicated problems and make the most of limited research dollars.

Methyl anthranilate as a rice seed treatment to deter birds

Red-winged blackbirds (Agelaius phoeniceus) and related species cause millions of dollars of damage annually to sprouting rice in Louisiana and Texas. Seed treatments that deter birds offer an approach to managing this problem, so we evaluated a formulation (ReJeX-iT AG-36) of methyl anthranilate (MA) in aviary and field tests to assess its potential as an avian feeding deterrent for rice seed. In a feeding trial with an untreated commercial ration as the alternative food, MA suppressed (P < 0.05) rice consumption at 2.5% (g/g) but not at lower rates. With untreated rice as the alternative food, however, repellency occurred at 1.0% MA (P < 0.05). Controlled field trials showed that seed loss from plots having a 1.7% MA treatment averaged 27 and 34% compared with control plot losses of 52 and 73%. We conclude that MA has potential in the management of blackbird damage to rice, particularly if MA residues on rice seed can be prolonged

Movement of Mexican Rice Borer (Lepidoptera: Crambidae) Through the Texas Rice Belt

Abstract Pheromone-baited traps were used to monitor the movement of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), through the Texas rice belt from 2000 to 2005. Based on location of discovery in each county and year, the average rate of spread from 1980 to 2005 was 23 km/yr. From 2000 to 2005, the leading edge of the infestation has moved 16.5 km/yr toward Louisiana. The 1.8-fold increase (99% confidence interval) of the area occupied from 2000 to 2005 in the Texas rice belt indicates an expansion of the distribution of E. loftini. If movement continues to occur at similar rates, E. loftini will reach Louisiana by 2008.

Identification and Biological Role of the Endosymbionts Wolbachia in Rice Water Weevil (Coleoptera: Curculionidae)

ABSTRACT Wolbachia spp. are obligate intracellular bacteria present in reproductive tissues of many arthropod species. Wolbachia infection status and roles in host reproduction were studied in the rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera, Curculionidae), an introduced species in China. We examined Wolbachia infection status in five populations in China where it reproduces parthenogenetically, and one native population in Southeast Texas, where it reproduces bisexually. All populations were infected by Wolbachia, and all specimens in each population were infected by Wolbachia of a single strain. Phylogenetic analyses based on multilocus sequence typing system indicated that Wolbachia in non-native L. oryzophilus weevils diverges evidently from those in native weevils. After treatments with tetracycline, parthenogenetic weevils reduced the fecundity significantly and eggs were not viable. Our results suggest that Wolbachia are necessary for oocyte production in L oryzophilus.

Diel flight periodicities of some Dytiscidae (Coleoptera) associated with California rice paddies

Abstract. Diel flight periodicities of Eretes sticticus (L.), Hygrotus medialis (LeConte), Laccophilus mexicanus atristernalis Crotch, Liodessus affinis (Say) and Thermonectus basillaris (Harris) were monitored with a rotary net machine and a black light trap. All were affected to some extent by air temperature, light intensity, and wind velocity.

DEVELOPING FLEXIBLE ECONOMIC THRESHOLDS FOR PEST MANAGEMENT USING DYNAMIC PROGRAMMING

The rice stink bug is a major pest of rice in Texas, causing quality related damage. The previous threshold used for assisting in rice stink bug spray decisions lacked flexibility in economic and production decision variables and neglected the dynamics of the pest population. Using stochastic dynamic programming, flexible economic thresholds for the rice stink bug were generated. The new thresholds offer several advantages over the old, static thresholds, including increased net returns, incorporation of pest dynamics, user flexibility, ease of implementation, and a systematic process for updating.

Economic Thresholds and Injury Levels for Insect Pests of Rice

Over 90% of the world’s rice is grown in Asia where more than 100 insect species attack the crop (Norton and Way 1990). Other rice-growing areas each with a unique complex of insect pests include Latin America, Africa, Australia, Europe, and the United States. Insects are a major constraint to world rice production which must increase from current levels of 460 to 760 million tons simply to keep pace with human population growth as projected for 2020 (Woodburn 1990). On a global scale, insects decrease rice yields an estimated 26% (Cramer 1967). The economic importance of insect pests of rice is illustrated by the fact that

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

910 million was spent throughout the world on insecticides applied to rice in 1988 (Woodburn 1990).

Stink Bug Species Composition and Relative Abundance of the Redbanded Stink Bug (Hemiptera: Pentatomidae) in Soybean in the Upper Gulf Coast Texas

ABSTRACT 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.

Oviposition and larval development of a stem borer, Eoreuma loftini, on rice and non-crop grass hosts

ABSTRACT Stink bugs are the primary arthropod soybean pests in the southern United States. Historically, important stink bug species damaging soybeans in the southern United States included the southern green stink bug Nezara viridula (L.), the green stink bug Chinavia hilaris (Say), and the brown stink bug Euschistus servus (Say) (Hemiptera: Pentatomidae). The redbanded stink bug, Piezodorus guildinii (Westwood), has recently become an economic pest of soybean in the southern region of the United States, especially in Louisiana and Texas. Little is known about current stink bug species composition and relative abundance in Texan soybean agro-ecosystems. To fill this gap, commercial soybean fields in the Upper Gulf Coast of Texas were sampled weekly during the growing season using a sweep net throughout R2 (full flowering) to R7 (beginning maturity) from 2011 to 2013. Adults and nymphs (third, fourth, and fifth instars) of redbanded stink bug, southern green stink bug, green stink bug, and brown stink bug were counted per 25 sweeps. The relative abundance of redbanded stink bug was significantly higher than any other stink bug species throughout 2011–2013. Over 65% of the total population of major stink bugs collected during this period were redbanded stink bugs and ≈19% were southern green stink bugs. The highest redbanded stink bug densities and the highest ratio of redbanded stink bug nymphs to adults were recorded at R7. Results from this study show that redbanded stink bug has become the predominant stink bug species in soybean in the Upper Gulf Coast of Texas.