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Studies to evaluate granular insecticides for control of Lissorhoptrus oryzophilus Kushel were conducted at Texas A & M University Agricultural Research and Extension Center from 1965 thru 1975. Bux® (m-(l-ethylpropyl) phenyl methylcarbamate (1–4) with m-(l-methyl=butyl) phenyl methylcarbamate) and carbofuran were found to be effective in preliminary tests. Time and rates of application studies with Bux indicate maximum larval control was obtained with rates of either 0.5 or 1.0 lb AI/acre made into the flood water 1 week postflood. Simular studies with carbofuran inclicate effective control with rates of 0.5 or 1.0 lb AI/acre applied either 1 or 2 weeks postflood. Maximum yield increases were obtained when the applications of insecticides were made 1 week postflood.

The rice water weevil (Lissorhoptrus orvzophilus KUSCHEL) was first recorded in Kagoshima Prefecture in May, 1984. The weevil was noted to have established itself in early planted paddy fields covering 52 ha in Ibusuki City in the Southern part of Satuma Peninsula. Thereafter, it was also found in two neighbouring towns, but further expansion of its distribution range was not confirmed in 1985 around Ibusuki City and the surroundings. However, this species was found in 1985 to be distributed over 200.3 ha of paddy fields with early maturing rice in Oosumi Peninsula and on the Amami Islands. The pest is considered to be dispersed by wind rather than by artificial means.

Based on atrophy of ovaries and hypertrophy of fat bodies, it is concluded that the rice water weevil, Lissorhoptrus oryzophilus Kuschel, overwintered in diapause in Louisiana. Weevils collected during Oct.–May and exposed to simulated summer conditions showed differences in duration of preoviposition and oviposition periods and in fecundity. More than 50% of weevils collected on or after the 3rd wk of Feb. oviposited, whereas less than 45% collected prior to this period oviposited. It is concluded that weevils were in diapause of variable intensity. About 1/7 of the overwintering females were mated and some contained resorbed eggs.

Rice field drainage beginning 10 d after flooding followed by a soil drying of 7-13 d provided larval control of rice water weevil, Lissorhoptrus oryzophilus Kuschel, comparable with that obtained with carbofuran applied at a rate of 0.67 kg (AI)/ha approximately 10 d after flooding. Leaf-feeding scars made by adults soon after flooding were used as a basis for making control decisions. During this 3-yr study, an action threshold based upon leaf-feeding scars would have correctly predicted subsequent larval infestations above or below a previously estimated economic injury level of 10 larvae per core soil sample in 87-95% of the 30 plots evaluated. In these plots, rice yield was not reduced by larval infestations >10 larvae per soil core.

150 infants aged under 6 months and admitted to hospital with acute gastroenteritis were treated with rice water (RW), rice-based electrolyte solution (RES), and the glucose electrolyte solution (GES) recommended by the World Health Organisation. Two-thirds of the patients were moderately dehydrated and only 8% had positive stool culture. Vomiting, present in 11%, did not interfere with successful oral rehydration. Before treatment serum electrolytes and other biochemical variables were similar in the three groups. After 48 h of treatment the blood urea nitrogen and serum creatinine were lower (p less than 0.05) in the RW and RES group than in the GES group. Serum potassium was also lower in the RW than in the RES group. RW and RES were superior to GES in reducing the frequency and volume of stool output and in producing weight gain.

A total of 106 cultivars of rice, Oryza sativa (L.), introduced, selected, or developed in the United States since the 1700s were evaluated for resistance to rice water weevil, Lissorhoptrus oryzophilus Kuschel, larval infestation, and adult foliage feeding in 1979 and 1980. The Phihppine cultivars Bontoc, Finindoc, and Carangiang; Nira, a pure line selection from an unknown Philippine variety: and Dawn, a hybrid with Philippine parents, all had significantly (P 30 larvae per core) larval populations.

Overwintering rice water weevils, Lissorhoptrus oryzophilus Kuschel, were held at different temperatures with and without food to determine the response of indirect flight muscle regeneration. Flight muscle regeneration has a temperature threshold of ca. 18°C. The rate of regeneration is greater at higher temperatures and when adults feed. Emergence of adult weevils from overwintering sites was monitored with sticky traps for 4 years near Stuttgart, Ark., and for 2 years near Crowley, La. The date adults emerged in the spring is closely related to springtime temperatures.

Small plot tests were conducted during 1959 and 1960 to control the larval stage of the rice water weevil, Lissorhoptrus oryzophilus (Kuschel). Aldrin and heptachlor were equally effective either when applied as a seed treatment or when mixed with fertilizer. Four ounces of the active ingredient per acre applied with fertilizer and 4 ounces of the active ingredient per 100 pounds of seed as seed treatment gave optimum control. Yield increases were obtained from controlling the insect in four of the five tests. Yield increases were significant in three of five tests.

In studies on the control of rice field mosquitoes in Bolivar County, Mississippi, in 1952–53, observations indicated that the dieldrin treatments employed were highly effective against the larvae of rice water weevil, Lissorhoptrus orysophilus Ksl. Airplane applications of dieldrin emulsion at rates of 0.5 or 1.0 pound per acre almost completely eliminated weevil infestations in rice fields (48 to 100 acres) during the entire 9- to 10-week test period. Small plot tests with dieldrin as an emulsion, impregnated pellets, or as a seed treatment, also were highly effective.

Five common variables in rice culture were investigated for their effeet on larval control of the rice water weevil Lissorhoptrus oryzophilus Kuschel by seed treatment. Soil types, methods of seeding, and storage of treated seed for as long as 5 months did not affect control appreciably. The ratio of aquatic grasses to rice plants and, at least indirectly, the rate of seeding influenced the level of control. As the ratio of aquatic grasses to rice plants increased, the level of control fell, apparently because some larvae that become established on aquatic grasses migrate during their development to nearby rice plants. The lateral movement of larvae was demonstrated in a field and insectary study.

Laboratory studies conducted during 1965 and 1966 using the topical-application technique demonstrated resistance to aldrin in the rice water weevil, Lissorhoptrus oryzophius Kuschel, in Louisiana. High levels (100- to two-fold) of resistance were found in weevils from Alsatia, Crowley, and Ville Platte. Intermediate levels (5- to 10-fold) of resistance in weevils were shown to be widespread over the major rice-producing area of Louisiana The more susceptible weevils were found principally around the fringes of the major rice area. The aldrin-resistant rice water weevils from Alsatia and Crowley also appeared to be resistant to endrin but not to methyl parathion and Nia 10242 (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate).

The culture and environment of lactating women not only affects the nutritional status of the mother through their effects in the selection of the diet and utilization of that diet, but also the nutritional status of the infant through their effects on the mother. Culture and environment can also have a more direct effect on the nutritional status of the infant, such as feeding practices. An intensive health and nutrition study was conducted on 26 lactating women and their infants in six villages in the Kathmandu Valley of Nepal which considered how the culture and environment influenced the nutritional status of this population. A detailed socioeconomic profile, health history and dietary history were obtained from the mothers by Nepalese public health workers. Anthropometric measurements and a physical examination by the team physician were performed on both the mothers and infants. During the three day study period, a 24-hour duplicate food composite was collected and subsequently analyzed for various nutrients. Analysis of the dietary composites indicated that the mothers consumed a low fat high carbohydrate diet. These diets were also higher than American Diets in neutral detergent fiber and phytate, which may exascerbate problems with minerals consumed in low amounts such as calcium (482 mg/day) and may even compromise minerals such as iron (33 mg/day) which was consumed in large amounts. Two special foods, jwano and gundruk, consumed by Nepalese women were examined for nutrient content and found to contain significant amounts of calcium, iron and magnesium. Fifty percent of the women studied supplemented their infants with lido, a rice water paste, because they felt their milk supply was inadequate. Anthropometric measurements and physical examination of the infants indicated adequate infant growth. The mothers physical exam revealed a 100% incidence of hepatitis A, a high apparent intestinal parasitic infestation and a stunting of growth.

Ronald C. Griffin, M. Edward Rister, Michael R. Parker, and Garry N. McCauleyAbstract companies are reflected in the price producersThe economic feasibility of investing in must pay to purchase the surface watersprinkler irrigation technology for rice pro- necessary for crop production (Griffin et al.).duction is investigated using linear program- Water costs have contributed to a decliningming and capital budgeting to identify the net profit margin in recent years. The averageannual benefits and net present value, respec- total cost for rice irrigation water in Texastively. Groundwater and both fiat rate and rose from $30.00 per acre in 1977 (USDA,volumetrically priced surface water sources of 1977) to $73.58 per acre in 1982 (Griffin et al.).irrigation water are analyzed. Under typical Irrigation water was responsible for 16 to 25practices occurring in rice production opera- percent of variable costs and 11 to 17 percenttions in the Texas Rice Belt, sprinkler irriga- of total costs associated with producing a ricetion technology is not profitable at current crop in 1982 (USDA, 1982). The current poorwater costs. Producers using volumetrically profitability of rice production enhances thepriced surface water have the greatest incen- need for Texas and other southern rice pro-tive to consider sprinkler irrigation, but water ducers to be economically efficient withprices must increase by over 250 percent for respect to water as well as other productionthe investment in a sprinkler irrigation inputs.system to become attractive. Yield reductions Beyond satisfying rice water requirements,associated with sprinkle-irrigated rice are a the primary purpose of the conventionalsignificant disincentive. For equivalent flood- flooding technique is to control weed growthand sprinkle-irrigated rice yields, an increase (McCauley). Creating flooded conditions,in water prices of over 175 percent is required however, consumes much more water thanbefore the investment in a sprinkler irrigation what is required for rice plant growth. In thesystem becomes economically feasible. Texas Rice Belt, for example, surveyresponse estimates of water use on flood-Key words: rice, linear programming, capital irrigated rice range from 1.7 to 7.4 feet perbudgeting, sprinkler irrigation, acre (Griffin and Perry). These figures in-technology, flood irrigation. elude, in varying proportions, water consumed

The spectrum of illness and the immunologic response produced by cholera in volunteers were studied. The strains of Vibrio cholerae used were classical Inaba 569B and classical Ogawa 395. An oral dose of 108 organisms in buffered saline was required to induce the diarrhea of cholera. When given with live organisms, NaHCO3 lowered the infecting dose from 108 to 104 organisms. Clinical manifestations of infection varied from culturally positive formed stools to "rice water" diarrhea. Severe diarrhea did not have an explosive onset but rather progressively increased in volume during a 24-hr period. In 45% of cases the stool was positive for V. cholerae before the onset of diarrhea. Titers of vibriocidal antibody rose after diarrhea, peaked the second week after challenge, and rapidly fell during the next four weeks.

Aeromonas sobria, a member of the Aeromonas hydrophila group, recently has been recognized as a gastrointestinal pathogen in adults. There have been a few documented cases, and these have come from far eastern countries, namely India, Thailand, and Indonesia. The authors have isolated a strain of A. sobria from a 62-year-old male patient suffering from diarrheal disease. He had no history of travel outside of the United States for several decades. He presented with a severe diarrheal disease that closely mimicked cholera, producing large quantities of green "rice water" stool. He was severely dehydrated and was in electrolyte imbalance. No other enteric pathogen could be detected. The organism presumptively was identified as Vibrio cholera (81.5% probability) by the Micro Scan system, but later was identified definitively as A. sobria using the API 20E and ZYM systems. Cell-free extract of this strain contained hemolysins, proteolytic enzymes, and enterotoxin. The strain closely fits the description of Burke and associates (J Clin Microbiol 1982; 15:48-52) for their group A, type 1 (VP positive, arabinose negative, enterotoxin producer). The patient was treated with tetracycline and recovered.

Diarrheal disorders and complications related to diarrhea especially dehydration continue to be a major problem in developing countries like India. Though oral rehydration with salt, sugar and water is a well accepted mode of treatment in uncomplicated cases, still ORS packets (WHO formula) or sugar (sucrose ORS formula) are not readily available in every house or hospital rice water with salt services as an equivalent alternative substitute in the rehydration therapy with good results.

A comparative study was carried out on the in vitro production of cholera toxin by 19 Vibrio cholerae El Tor isolates from patients with cholera in South Africa, one El Tor isolate from a patient in Malawi (a country approximately 1000 km north-northeast of South Africa), 6 El Tor and 12 classical type isolates from patients in Bangladesh, and 5 culture collection classical strains. Identical phage types and indistinguishable toxigenicities among the South African and Malawi V. cholerae, representing isolations obtained over a 10-year period, indicated that essentially a single strain was involved in the cholera of these regions. Similarly, phage typing and toxin profiles indicated that the 12 classical and 6 El Tor V. cholerae cultures in Bangladesh, all isolated in November 1983, represented just two strains. As assessed by titrations in Y-1 mouse adrenal and Chinese hamster ovary cell lines, the general order of toxigenicities was Bangladesh and culture collection classical greater than Bangladesh El Tor greater than southern African El Tor. The African isolates consistently gave rise to very low titers. Their relative reluctance to produce the toxin in vitro compared with the culture collection classical strains, particularly strain 569B, was confirmed by rocket electrophoresis. In somewhat of a contrast, maximum in vivo titers in rice water stools from cholera patients in South Africa and from both classical and El Tor type cholera patients in Bangladesh were essentially equal. It is postulated that under the continuous culture conditions that occur in vivo, cholera toxin concentrations can accumulate to a maximum level, depending on the rate of purging by the diarrheal fluid rather than the toxigenicity of the infecting stain. The relevance of these findings to the relative severities of classical and El Tor types of cholera is discussed.

Vibrio alginolyticus was isolated from the “rice water” diarrheal stool of a female patient with acute entero-colitis, and from the trout roe which she ate. Subsequently, it was clearly demonstrated that, besides of Vibrio cholerae and Vibrio parahaemolyticus, Vibrio alginolyticus was also enteropathogenic for humans. Additionally, we described the difference in the colony formation on some commercial thiosulfate citrate bile salts sucrose (TCBS) agars when Vibrio alginolyticus and Vibrio cholerae were tested.

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Numerous studies have addressed effects of rising atmospheric CO2 concentration on rice biomass production and yield but effects on crop water use are less well understood. Irrigated rice evapotranspiration (ET) is composed of floodwater evaporation and canopy transpiration. Crop coefficient Kc (ET over potential ET, or ETo) is crop specific according to FAO, but may decrease as CO2 concentration rises. A sunlit growth chamber experiment was conducted in the Philippines, exposing 1.44-m2 canopies of IR72 rice to four constant CO2 levels (195, 390, 780 and 1560 ppmv). Crop geometry and management emulated field conditions. In two wet (WS) and two dry (DS) seasons, final aboveground dry weight (agdw) was measured. At 390 ppmv [CO2] (current ambient level), agdw averaged 1744 g m-2, similar to field although solar radiation was only 61% of ambient. Reduction to 195 ppmv [CO2] reduced agdw to 56±5% (SE), increase to 780 ppmv increased agdw to 128±8%, and 1560 ppmv increased agdw to 142±5%. In 2013WS, crop ET was measured by weighing the water extracted daily from the chambers by the air conditioners controlling air humidity. Chamber ETo was calculated according to FAO and empirically corrected via observed pan evaporation in chamber vs. field. For 390 ppmv [CO2], Kc was about 1 during crop establishment but increased to about 3 at flowering. 195 ppmv CO2 reduced Kc, 780 ppmv increased it, but at 1560 ppmv it declined. Whole-season crop water use was 564 mm (195 ppmv), 719 mm (390 ppmv), 928 mm (780 ppmv) and 803 mm (1560 ppmv). With increasing [CO2], crop water use efficiency (WUE) gradually increased from 1.59 g kg-1 (195 ppmv) to 2.88 g kg-1 (1560 ppmv). Transpiration efficiency (TE) measured on flag leaves responded more strongly to [CO2] than WUE. Responses of some morphological traits are also reported. In conclusion, increased CO2 promotes biomass more than water use of irrigated rice, causing increased WUE, but it does not help saving water. Comparability with field conditions is discussed. The results will be used to train crop models.

Cholera is endemic in Guinea, having suffered consecutive outbreaks from 2004 to 2008 followed by a lull until the 2012 epidemic. Here we describe the temporal-spatial and behavioural characteristics of cholera cases in Conakry during a three-year period, including the large-scale 2012 epidemic. We used the national and African Cholera Surveillance Network (Africhol) surveillance data collected from every cholera treatment centre in Conakry city from August 2011 to December 2013. The prevalence of suspect and confirmed cholera cases, the case fatality ratio (CFR), and the factors associated with suspected cholera were described according to three periods: pre-epidemic (A), epidemic 2012 (B) and post epidemic (C). Weekly attack rates and temporal-spatial clustering were calculated at municipality level for period B. Cholera was confirmed by culture at the cholera national reference laboratory. A total of 4559 suspect cases were reported: 66, 4437, and 66 suspect cases in periods A, B and C, respectively. Among the 204 suspect cases with culture results available, 6%, 60%, and 70% were confirmed in periods A, B, and C, respectively. With 0.3%, the CFR was significantly lower in period B than in periods A (7.6%) and C (7.1%). The overall attack rate was 0.28% in period B, ranging from 0.17% to 0.31% across municipalities. Concomitantly, a cluster of cases was identified in two districts in the northern part of Conakry. At 14%, rice water stools were less frequent in period A than in period B and C (78% and 84%). Dehydration (31% vs 94% and 89%) and coma (0.4% vs 3.1% and 2.9%) were lower during period B than in periods A and C. The treatment of drinking water was less frequent in period A, while there were more reports of recent travel in period C. The epidemic dynamic and the sociological description of suspect cases before, during, and after the large-scale epidemic revealed that the Vibrio cholerae was already present before the epidemic. However, it appeared that infected individuals reacted differently in terms of disease severity as well as their access to treated water and travel habits. Such an in-depth description of cholera epidemics should be systematically carried out in cholera endemic settings in order to prioritize higher risk areas, identify transmission factors, and optimize preventive interventions.

Insecticides were evaluated in five experiments at the Rice Res. and Ext. Cent, in Stuttgart, Ariz. Rice was planted in Crowley silt loam: ‘Starbonnet’ on 11 May for tests I to IV and ‘Lebonnet’ on 8 June for test V. Each test was arranged in a randomized complete block design with four (Tests I and II) or three (Tests III to V) replications. All plots were sampled for root-feeding larvae by taking five soil cores (9 cm diam x 7 cm deep) from the drill rows of each plot; they were processed by washing through a #40 US Standard soil testing sieve and floating the larvae out in brine.

Rice seed was treated with insecticides 25 May. For each treatment 2 lb of seed were combined with the insecticide in a seed treater similar to a concrete mixer. In Test I each insecticide was mixed with water in sufficient quantity to thoroughly coat the seed and 3% Methocel Gel was added to Ectiban and Demon. In Test II insecticides were mixed with water or acetone. A sticker consisting of equal volumes of water, glycerin, and 75% ethanol was added to each seed-treatment in Test II during mixing. The seed was air dried and packaged in paper bags. The 4 by 15 ft plots were planted 26 May and flooded 28 June. Furadan 3G was applied 6 Jul. All plots were sampled for root-feeding larvae 19 and 20 July by taking 5 soil cores (9 cm dia by 7 cm deep) from the drill rows of each plot. Cores were processed by washing through a #40 US Standard testing sieve and floating the larvae out in brine.

Insecticides were tested on heading rice at the Rice Res. and Ext. Cent, at Stuttgart, Arz., for control of rice stink bug and rice water weevil adults. Both insect species were exposed to insecticides by confining them together on rice panicles with organdy sleeve cages (30 cm diam. by 55 cm long). First, cages were placed over panicles, tied off at bottom, rolled down and covered with aluminum foil. Then after each insecticide was applied at 10 gal/acre with a compressed air single nozzle sprayer, foil was removed and insects put into cages within 10 minutes after application. A total of 42 insects of each species were used per treatment, i.e., seven of each species in each of two cages per plot arranged in a randomized complete block design with three replications. After 4 days, caged plants were cut and transported to the laboratory where cages were opened and the number of dead and living insects were determined.

PIP: In Singapore the World Health Organization's (WHO's) oral electrolyte solution for the treatment of infantile gastroenteritis has been used for 6 years and rice water has been used for 8 years. The rice water is the water used in preparing boiled rice or congee and is a slightly starchy solution. As the impression was that rice water was as effective as or even better than the oral electrolyte solution, a trial was conducted of the 2 solutions in babies with gastroenteritis admitted to the Department of Pediatrics of the National University of Singapore. Alternate cases were assigned consecutively to the oral electrolyte solution or to rice water. There were 63 patients on oral electrolyte and 67 on rice water. Milk was totally withdrawn for 24 hours after admission and the babies were put on 1 or the other oral solution. Intravenous 3.75% glucose and 0.23% saline was given at the same time to babies considered to be more dehydrated. On day 2, quarter strength powdered milk was given, followed by half strength on day 3, three-quarters strength on day 4, and full strength on day 5. Electrolyte and urea values were compared, both for "drip" versus "no drip" within oral treatment groups and between electrolyte solution and rice water groups (20 comparisons altogether). There were only 3 significant differences, and these might be explained by the intravenous drip and by the better water absorption from rice water than from the oral electrolyte solution. The most obvious difference in the 2 groups was in the effect on diarrhea (stools/day). Rice water cut down the number of stools more effectively than did oral electrolyte solution. No patient died, and there were no pathological sequelae in any of the 130 patients. Rice water can be tried as a more practical alternative to oral electrolyte solutions since there are problems with providing oral elecrolyte solutions to all babies with diarrhea in the developing countries and ensuring sterility.

The chromosomes of the so-called rice water weevil,Lissorhoptrus oryzophilus, Kuschel obtained from Tokoname City, Aichi Prefecture, were studied in both oogonial and oocyte-maturation divisions in squash and sectioned slides, respectively. The chromosome number was confirmed as exactly 33 in both divisions. No reduction division takes place. It is therefore concluded thatLissorhoptrus oryzophilus is a parthenogenetic triploid in Tokoname City.

Eggs of Lissorhoptrus oryzophilus Kuschel were exposed in the laboratory to constant water temperatures of 25°, 30°, 35°, and 40°C. None hatched at the high temperature. The average number of days to hatch were 9, 6, and 4 when exposed to the 3 lower constant temperatures, respectively. The response of eggs of different ages held at 25°C but exposed to 45°C for different periods of time indicated little mortality resulted from 1–3-h exposure. Mortality occurred when eggs were exposed to 45°C for 6, 9, or 15 h, but eggs midway in their development seemed more tolerant than 2–3 day old eggs or those in the last stages of development. The rate of development was slower by ca. 1 day when eggs were exposed to 45°C, regardless of the time of exposure.

Rice was planted in Cowley silt loam at the Rice Res. and Ext. Cent., Stuttgart, AR. Plots for the CN 11-3877 10G preflood test were 5 by 15 ft. All other plots were 5 ft dia cm and enclosed by aluminum flashing to prevent water movement. Each test was arranged in a randomized complete block design with three replications and flooded 16 June. All the nongranular treatments were applied with an air powered single nozzle sprayer at rate of 58 gal/acre. Those applied with oil were mixed in Agridex with 0.2% Ortho X-77. Granular insecticides were applied by hand shaker. All plots were sampled for root-feeding larvae 7 and 8 July by taking five soil cores (9 cm dia by 7 cm deep) from the drill rows of each plot; they were processed by washing through a#40 US Standard testing sieve and floating the larvae out in brine.

A test was conducted in 1959 to investigate the effects of nitrogen levels on rice water weevil, Lissorhoptrus oryzophilus (Kuschel), larval populations and the resulting yields of rice. Data recorded on the number and total length of adult feeding scars indicated no significant difference between rates of 0, 40, 80, and 120 lb. of nitrogen per acre or between untreated plots and plots treated to control rice water weevil larvae. Data on larval populations showed an increase with each increase in rate of nitrogen and differences between treated and untreated plots. The yield data showed differences among all rates of nitrogen and between treated and untreated plots. The yield increases were approximately linear with each increase in rate of nitrogen in both the treated and untreated plots.

The small size and aquatic habits of the rice water weevil, Lissorhoptrus oryzophilus Kuschel, make observation difficult and, consequently, led early observers to make partially erroneous assumptions concerning the oviposition activity of the female and the location of the 1st-stage larvae. Early investigators reported that the female rice water weevil placed the egg longitudinally in the roots of the rice plant (Tucker 1912, Webb 1914, Ingram 1927, Isley and Schwardt 1930). The eggs reportedly hatched, and the larvae fed within the roots. This observation was partially correct, and the assumption was logical as the adults actually spend considerable time crawling around the base of the plant and sometimes enter the soil by crawling down the roots. In addition, 1st-stage larvae are frequently found in the roots. However, recent studies have shown that the eggs are inserted primarily (98.5%) in the submerged leaf sheath (Grigarick and Beards 1965, Everett 1965, Everett and Trahan 1967). Newly hatched larvae reportedly feed for a time in the leaf sheath and then crawl down the plant and enter the roots (Grigarick and Beards 1965). My recent observation confirms these reports with the exception that after hatching, the larvae apparently leave the exit hole and move by gravity through the water to the soil and roots. This observation agrees with Kuschel's (1951) statement that “the larva is ectophytic and because of the absence of locomotive appendages—which the dorsal spines replace very imperfectly—as in all members of the family, it can only move very slowly and in a dense medium like the mud of ponds.” Thus, the 1st-stage larvae are outside the plant and soil for a short time, and during this period the insect is in the most vulnerable stage in its life cycle.

Characters previously described for determining the sex of rice water weevils, Lissorhoptrus oryzophilus Kuschel, are either difficult to use or unreliable. Both Newell (1913) and Tucker (1912) reported that the females were slightly larger and more distinctly marked with black than the males. The color pattern is usually obscured by scales, dirt, or algae, however, and Newell (1913) did not consider it a useful character for sex determination. W. D. Pierce was reported by Newell (1913) and Tucker (1912) as having made a study of secondary sexual characters. From this study, Pierce determined that the antennal scrobe on the beak was slightly curved in the female and straight in the male. Because of the curvature of the beak, this character is difficult to use and may result in errors of judgment. At best, it is useful for restricted numbers of weevils and then only after careful study and practice.

The median depression on the last abdominal sternite is a useful character for distinguishing, in the field, the male from the female adult of all North American Hylobius species.Everett and Newsom (1964) used a midline depression or sulcus on the abdominal sternites to separate the sexes of the rice water weevil, Lissorhoptrus oryzophilus (Kushel), and other weevils that are not closely related to species of Hylobius in North America. The male of Hylobius abietis L., a European relative, is distinguished from the female by a saucerlilte depression on the last sternite (Anonymous 1952). Millers et al. (1963) state that the first and second visible abdominal sterna of the male H. rhizophagus Millers are concave, and the fifth has a slight median depression; the female sterna are convex.

Several experimental insecticides used as seed treatments were evaluated for control of rice water weevil, Lissorhoptrus oryzophilus Kuschel, in 1963, 1964 and 1965. Fenthion, carbaryl, Nia 10242 (2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate), CL 43064 (2-(diethoxy-phosphinothioylimino)-1,3-dithiolane), Bayer 25141 ( O,O- diethy O -[ p -(methylsulfinyl) phenyl] phosphorothioate), Matacil® (4-dimethylamino- m -tolyl methycarbamate), GC 4072 (2-chloro-1-(2,4-dicholrophenyl) vinyl diethyl phosphate), and U-12927 (6-chloro-3,4-xylyl methylcarba-mate) were sufficiently effective to merit more intensive testing.

The experiment was conducted at the Texas A&M University Agricultural Research and Extension Center at Beaumont. The design was a randomized complete block with 5 treatments and 4 replications. Each plot was 6 × 13 ft and surrounded by a metal barrier to prevent contamination among plots. Plots were fertilized 22 May with urea at 110 lb nitrogen/acre. Rice was broadcast in each plot 22 May at 100 lb seed/acre. The plots were flooded 22 May and drained 24 h later. Propanil was applied at 3.0 lb (AI)/acre on 29 May and 16 Jun. On 19 Jun the permanent flood was established and maintained to maturity. Before the onset of the permanent flood and after the first irrigation on 23 May, additional irrigations were applied when the soil cracked from drying. On 9 Jul at panicle initiation, 60 lb nitrogen/acre in the form of urea was applied. Three and 9 days after the onset of the permanent flood, the Dimilin 25W treatments were applied with an atomizer supplied with COa propellant using a spray volume of 10 gal/acre. Furadan 3G was applied at 0.6 lb (AI)/acre 7 days after the onset of the permanent flood using a hand-held shaker. From 10 Jul to 20 Jul, 10 soil cores (4 inches diam × 4 inches deep) containing 1 plant/core were randomly selected and removed from each plot. Plants were washed in a 40-mesh screen bucket, and rice water weevil larvae and pupae were recovered and counted. Washed plants were measured for height, root length, and number of tillers and leaves. Plots were harvested at maturity on 25 Sep.