Weevil Mortality Research Articles

Taxus, Chemical Control of Black Vine Weevil Adults, Wooster, Oh, 1983

Abstract Efficacy of insecticides for control of black vine weevil adults was evaluated by spraying field plants.and feeding treated foliage to weevils in the laboratory. A CO2 compression sprayer operating at 40 lb/in2 with a TeeJet SS 8004 flat fan nozzle was used to spray plants to runoff on 19 Jul. under sunny skies at 26°C and an 8 to 16 kph breeze. Three plants 0.6 m tall were sprayed with each treatment. Subsequently, at 1, 3, and 7 days posttreatment, 10 to 15-cm twigs were clipped from treated plants and placed individually in 9 by 16 cm cylindrical paper cartons fitted with nylon mesh tops. Three cartons (= replicates) were used for each treatment, each with five ovipositing weevils. Weevils had been collected previously from a nursery in Lake Co. and held at 22°C at 90% RH with taxus foliage until used in this test. Weevil mortality was recorded 72 h after they were introduced to the cartons.

Taxus, Black Vine Weevil Control, Wooster, Oh, 1982

Abstract The influence of rate, formulation, and spreader-sticker on efficacy of Turcam in controlling black vine weevil adults was evaluated by spraying field plants to runoff and feeding treated foliage to weevils at specified intervals in the laboratory. Finished sprays were applied with a CO2 compression sprayer operating at 40 lb/in2 with a Tee Jet SS8004 flat fan nozzle on 16 Aug. under sunny skies at 26 to 29°C and a slight breeze. Three plants 0.6 m tall were thoroughly sprayed with each treatment. Subsequently, 10- to 15-cm twigs were clipped from each treatment plant and placed individually in 9 by 16 cm cylindrical paper cartons fitted with nylon mesh tops. Three cartons (= replicates) were used per treatment, each with five ovipositing weevils. Weevils had been collected from taxus at a nursery in Lake Co., held in a rearing room at 22°C and 90% RH, and fed fresh taxus foliate before caging with infested foliage. Weevil mortality was assessed 72 h after weevils were introduced to the cartons.

Killing power of the red imported fire ant [Hym.: Formicidae]: a key predator of the boll weevil [Col.: Curculionidae

The red imported fire ant,Solenopsis invicta Buren, was identified as a key predator of the boll weevil,Anthonomus grandis Boheman. Although key factor analysis does not guarantee that the key factor is the causative agent, the evidence of boll weevil mortality was so clear that the fire ant could be identified as causing the mortality. Ant predation on immature boll weevils during the summer of 1981 averaged 84%. When this predation was combined with other natural mortality factors, the weevil population density throughout the season never exceeded levels that required control measures.

Cotton Bud Drying: Contributions to Boll Weevil Mortality

A model of immature boll weevil, Anthonomus grandis Boheman, mortality as it relates to cotton, Gossypium hirsutum L., bud drying is presented. The model synthesizes the effects of bud size, temperature, and relative humidity on immature survival. Favorable comparisons with two experimental data sets demonstrate that the bud drying mortality model contains the essential components and mechanisms to adequately explain this major (in many regions) contributing factor to immature weevil mortality.

Fall Mortality of the Boll Weevil 1 in Fallen Cotton Squares, with Emphasis on Parasite-Induced Mortality 2

Studies were conducted in the northern Texas rolling plains from mid-September to early November 1977 to 1979 to determine the amount of fall boll weevil, Anthonomus grandis grandis Boheman, mortality occurring in cotton squares. Apparent and real mortalities were determined for the immature boll weevil stages—egg to 1st instar, 2nd to 3rd instar, pupa, and teneral adult—for each weekly field-collected cohort. Total real boll weevil mortality increased from 40 to 70% in early October to 100% by late October each year. Parasites caused a significant amount of indispensable boll weevil mortality during early October, but parasitization was not high enough throughout the fall to effectively control the boll weevil.

Rearing the Maize Weevil 1 on Maize Genotypes When Aflatoxin-Producing Aspergillus flavus and A. parasiticus Isolates Were Present 2

Maize weevils, Sitophilus zeamais Motschulsky, either untreated or exposed to spores of Asperigillus flavus (Link) or A. parasiticus Speare, were fed on several endosperm genotypes of maize, Zea mays L. The maize with high-amylose germplasm sustained significantly more weevil damage and less overall aflatoxin contamination. Exposure of weevils to an A. parasiticus isolate resulted in significantly higher weevil mortality and aflatoxin contamination than exposure to an A. flavus isolate or to no treatment. Levels of aflatoxin contamination were positively correlated with weevil mortality; however, high levels of toxin did not completely eliminate weevil infestation from the grain.

Histopathology of Midgut of Mass Reared, Irradiated Boll Weevils Contaminated with Staphylococcus aureus and Streptococcus Sp.1

Bacterial contamination and irradiation cause rapid deterioration of midgut epithelium of Anthonomus grandis grandis Boheman. Staphylococcus aureus Rosenbach and Streptococcus sp. greatly accelerate the effects of irradiation, resulting in destruction of the tissues within a few days. The bacterial damage to the midgut causes premature mortality of the boll weevils.

Reduction of Mycoflora and Control of In-Shell Weevils in Pecans Stored Under High Carbon Dioxide Atmospheres

WELLS, J. M., and J. A. PAYNE. 1980. Reduction of mycoflora and control of in-shell weevils in pecans stored under high carbon dioxide atmospheres. Plant Disease 64:997-999. High carbon dioxide (C0 2) atmospheres reduced the mycoflora and controlled in-shell weevils in pecans stored under accelerated storage conditions of 7 C and 65% relative humidity. After 5 mo in atmospheres of 21% oxygen (02) and 30% CO2, pecan weevil mortality was 100%, total mycoflora isolated from kernels was significantly reduced, and off-flavors had not yet developed in the kernels. In atmospheres of 3 and 10% CO 2 (plus 21% 02) or in 1% 02 (with or without 30% CO2), weevil mortality was less than 100%. Objectionable off-flavors developed in high CO2 atmospheres after 6 mo. Alternaria and Pestalotia spp. were the fungi most frequently isolated from pecans held in air. After 5 mo in high CO2 atmospheres, Alternaria, Penicillium, and Fusarium spp. were the most frequently isolated fungi. In the southeastern United States, pecan (Carya illinoensis (Wang.) K. Koch) nuts are harvested from October to January. Much of the crop is refrigerated and stored to supply shelling plants with pecans throughout the year (11). In good crop years, refrigerated storage is an important means of holding excess supply until market conditions become more favorable to the producer. Since a heavy crop year is inevitably followed by a light crop year because of the alternate bearing nature of the pecan tree, longterm storage of pecans is also important in stabilizing the supply. Pecans are semiperishable. Highquality pecans may be held at 0-2 C for 1 yr before detectable off-flavors or rancidity develop (12). Not all pecans are of high quality at the beginning of storage, however. Late-harvested nuts may have lost freshness of flavor and the desirable light amber kernel color. Pecans may also be infested with the pecan weevil (Curculio caryae (Horn)), which damages kernels and provides avenues of invasion for postharvest storage fungi (9). Although refrigerated storage arrests the development of storage fungi and reduces damage caused by insects, it does not significantly affect survival of these organisms (5,8). Control is important, Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply approval to the exclusion of other products that also may be suitable.

Citrus, D. Abbreviatus Control, Plymouth, Florida, 1979

Abstract Aerial applications of Orthene were made to citrus groves and to a nursery using fixed wing aircraft equipped with the following: 1) Micronair rotary atomizers - volume 5 and 8 gal/acre; 2) D 8-45 nozzles - volume 8 gal/acre. Treatments were compared to a hydraulic ground spray applied to runoff. Foliage was collected randomly from 10 trees per treated area and an untreated check area. The foliage was placed in ten 32-oz cups immediately after treatment and 10 adult weevils were added/cup. Cups were then covered with wire mesh. Weevil mortality counts were made after 1 day and 3 days. Additional foliage was collected at 3, 6, 9 days posttreatment and tested in the same way.

Compatibility of Rhinocyllus conicus1 and 2,4-D (LVA) 2 for Musk Thistle Control

Herbicidal effect on Rhinocyllus conicus Froet., a thistle head weevil, was studied by examining the mortality, emergence rates and weights of weevils developing from plants treated with 2,4-D (LVA). Infested heads, obtained by caging ovipositing R. conicus on primary heads of musk thistle ( Carduus nutans L.) (resembles C. thoermeri Weinmann), were treated with 2,4-D at 1.68 kg/ha 0–3 wk after oviposition. Mortalities of larvae developing from untreated plants and those plants sprayed 1–3 wk were significantly lower than mortality from plants sprayed within 48 h of oviposition. The latter failed to support larval development beyond the 2nd instar. Developmental times and weights of weevils that emerged from blooms sprayed at 1, 2, and 3 wk were not significantly different from controls. Plants sprayed up to 2 wk after oviposition (late-bud to early-bloom) did not produce viable seeds, but treatments at 3 wk after oviposition (full-bloom) allowed 10% germination of seeds not damaged by R. conicus in primary heads, and plants survived to produce additional heads. Treatment of musk thistles with 2,4-D at late-bud to early-bloom stage of the primary heads prevented formation of viable seeds without adversely affecting R. conicus development.

Citrus, D. Abbreviatus Control, Plymouth, Florida, 1978

Abstract Each insecticide treatment was applied to 5 citrus trees (tree height ca. 8 ft) by a hydraulic sprayer as a dilute solution sprayed to drip. Two hr after treatment, field-collected adult weavils were caged on sprayed trees, 5 weevils/cage. Weevil mortality counta were made after 1- and 3-da exposure. Additional cages were added at 3, 6, and 9 da posttreatment when an insecticide demonstrated residual activity. Tests were conducted in September-October, the period of peak weevil activity.

Groundnut oil treatment for the control of Callosobruchus maculatus (F.) during cowpea storage

Groundnut oil at 5 ml/kg completely protected cowpea seeds in storage from Callosobruchus maculatus (F (F.) for up to 180 days. The treatment had no adverse effects on cooking time or taste of the cooked beans or on germination even after 6 months storage. The oil treatment prevented emergence of progeny rather than affecting oviposition or mortality of the adult weevils. Groundnut oil entered the egg of C. maculatus through the micropyle, and in 1 to 2 day old eggs, protoplasmic movement was stopped and the protoplasm coagulated. In 3 to 5 day old eggs, where the larvae were partially or fully formed, larval death occurred within minutes of the entry of the oil.

Seasonal Incidence and Effect of a Mermithid Nematode Parasite on the Mortality and Egg Production of the Rice Water Weevil, 1Lissorhoptrus oryzophilus2

A mermithid nematode parasite was observed in rice water weevils in the Stuttgart, Ark., area 1973–1976. Intensive observations for one season indicated that the nematode caused weevil mortality and reduced weevil egg production. The nematode was found almost exclusively in female weevils. Peak abundance occurred the last of June with a small 2nd peak in early Aug.

Temperature Optima for Development of Neochetina eichhorniae and Orthogalumna terebrantis

Mottled waterhyacinth weevils, Neochetina eichhorniae Warner, and waterhyacinth mites, Orthogalumna terebrantis Wallwork, were tested for mortality, feeding, oviposition, and emergence at 4 temperature regimes, viz. 5-25@*, 10-30@*, 15-35@*, and 20-40@*C. Highest mortality for both species occurred at the 2 extreme regimes. Lowest weevil mortality, 41.2%, occurred at 15-35@*C and lowest mite mortality, ca. 6-7%, at 10-30 and 15-35@*C. Weevil oviposition and feeding were significantly (P= 500/25 females, at the 3 highest temperature regimes, and development from immatures to adults, 42.3% emergence, was significantly highest at 10-30@*C. These data correspond generally to field observations.

Citrus, D. Abbreviatus Control, Plymouth, Florida, 1976

Abstract Each insecticide treatment was applied to 5 citrus trees (tree height ca 8 ft) by a hydraulic sprayer as a dilute solution sprayed to drip. Two hours after treatment, field-collected adult weevils were caged on sprayed trees, 5 weevils/cage. Weevil mortality counts were made after 1- and 3-day exposure. Additional cages were added at 3, 6, 9, and 12 days posttreatment when an insecticide demonstrated residual activity. Tests were conducted in September-October, the period of peak weevil activity.

Detia Ex-B® for Phosphine Fumigation in Sacked Milled Rice2

A powdered formulation of aluminum phosphide (Detia Ex-B®) in paper packets that each released 11 g of phosphine gas was tested against adult confused flour beetles, Tribolium confusum Jacquelin duVal, and immature rice weevils, Sitophilus oryzae (L.), in 3 stacks of bagged milled rice covered with 6-mil polyethylene film. Complete mortality of all confused flour beetles in all stacks was observed after a 7-day exposure. Complete mortality of immature rice weevils after a similar exposure occurred in only 1 stack. Survival of the rice weevils was related to the maximum concentrations of gas produced in each stack and to the age of the weevils when fumigated. When gas concentrations in each stack were measured with Auer® indicator tubes and by a GLC method, the indicator tubes appeared to yield data as reliable as the chromatographic method. Variations introduced by sampling procedures and by handling or transporting samples to the chromatograph apparently negated the greater inherent accuracy of the GLC method.

Small-Plot Tests with Synthetic Juvenile Hormones on Alfalfa Weevil in Maryland and Pennsylvania

When synthetic juvenile hormones were field-tested in 1971 and 1972 in Maryland and Pennsylvania vs. 4th instars of Hypera postica (Gyllenhal), 1 compound significantly increased the mean weight of normal adults, and substantially increased the mortality of pupal-teneral adult weevils. A dose-mortality correlation was observed with 6,7-epoxy-3,7-dimethyl-l-(3,4-[methylenedioxy]phonoxy)-2-nonene, and repeatable biological activity was demonstrated at both locations, but the 2nd application often did not increase performance. At any given dose, fewer than 10% of the live adult weevils had morphogenic aberrations. No untimely ovipositional activity that indicated premature termination of adult diapause was observed.

Dichlorvos and Gardona as protectants for stored wheat against granary weevil infestations in laboratory studies.

Laboratory studies were conducted to determine the relative effectiveness of Gardona® (2-chloro-1-(2,4,5-trichlorophenyl) vinyl dimethyl phosphate) and dichlorvos applied separately and in combination to protect stored hard red winter wheat subjected to an infestation by Sitophilus granaries (L.) Effective control (95–100% mortality) of the adult weevils was obtained with a 20-day exposure to 8 ppm Gardona applied to the wheat or a minimum of 10-days’ exposure to 15 ppm Gardona. Dichlorvos at 2 ppm and a weevil exposure period of 5 days also provided effective control. Gardona at 15 or 20 ppm reduced weevil reproduction significantly, while dichlorvos at 4 ppm inhibited reproduction. In general, the Gardona-dichlorvos mixtures were more effective as the percent of dichlorvos was increased.

Diatomaceous earth for confused flour beetle and rice weevil control in rough, brown, and milled rice.

A diatomaceous earth produced 100% mortality in rice weevils, Sitophilus oryzae (L.), and confused flour beetles, Tribolium confusum Jacquelin duVal, exposed for 21 days in rough rice treated with dosages of 1.75 and 3.5 g/kg, respectively. Milled and brown rice required dosages of 3.5 and 5.25 g/kg, respectively, to effect 100% rice weevil mortality. More than 56 days were required to effect 100% mortality in confused flour beetles in brown rice treated with 7.0 g/kg. Lower mortalities in milled and brown rice appeared to result from saturation of the diatomaceous earth by oils from the surface of the lice kernels. In brown rice, aged treatments produced lower rice weevil mortalities than did fresh treatments, and preconditioning of the dust by exposing it to milled or brown rice rendered it less effective against confused flour beetles when it was removed after 21 days and applied to rough rice.

Effects of Temperature and Photoperiod on the Toxicity of Azinphosmethyl and Malathion to the Boll Weevil1

Toxicities of ultra-low-volume sprays of azinphosmethyl and malathion to Anthonomus grandis Boheman were evaluated under various photoperiods and temperatures. Weevils were exposed to insecticide-treated plants and held in 6 test environments: 80°F in continuous light (LL); 80°F and a photoperiod of LD 10:14 (i.e., 10 hours of light and 14 hours of dark per 24-hour cycle); 62-80°F truncated temperature change in LD 10:14; 62-80°F gradual temperature change in LD 10:14; 62°F in LL; and 62°F in LD 10:14. Toxicity produced by both insecticides showed a positive temperature coefficient as greater weevil mortalities occurred at higher temperatures than at lower. Azinphosmethyl killed greater percentages of weevils than malathion in the warmer temperature regimens of 80°F in LL, 80°F in LD 10:14, and 62-80°F truncated temperature change in LD 10:14. Malathion was more toxic to weevils than azinphosmethyl in the cooler temperature regimens of 62°F in LL, 62°F in LD 10:14, and 62 to 80°F in LD 10:14 gradual temperature change. Whereas temperature exerted an obvious influence on the toxicities of malathion and azinphosmethyl to boll weevils, no apparent effects were due to photoperiodism.