Field Rate Concentration Research Articles

Sublethal Effects of Insect Growth Regulators on Boll Weevil (Coleoptera: Curculionidae).

Immature stages of the boll weevil, Anthonomus grandis grandis Boh. (Coleoptera: Curculionidae), develop protected inside cotton fruiting structures. Therefore, the adult beetles have become the main target of insecticide applications. The use of insect growth regulators (IGRs) is recommended against immatures, even though they may also affect the survival and reproductive traits of adult insects. The present study evaluated the impact of a juvenile hormone analog (pyriproxyfen), an ecdysteroid agonist (methoxyfenozide), and a chitin biosynthesis inhibitor (lufenuron) on adult cotton boll weevils, a key cotton pest. Mated and virgin beetles were treated by feeding them contaminated squares and cotton leaf discs that were previously immersed into pyriproxyfen, methoxyfenozide, and lufenuron solutions at field-rate concentrations. After exposure, treated couples were caged onto cotton plants, and survival, fecundity, and egg viability were evaluated. The IGRs neither affected the survival nor fecundity of adult boll weevils. On the other hand, egg viability was significantly reduced by lufenuron, regardless of whether the females were treated premating or postmating or whether their pairs were either treated or untreated. However, egg viability increased as the females aged since the initial exposure date to lufenuron, indicating a potential transovarial effect of this insecticide. Our results indicate that pyriproxyfen and methoxyfenozide do not affect adult boll weevils, whereas lufenuron temporarily reduces the egg viability of this key cotton pest.

Lethal effects of λ-cyhalothrin and Emamectin benzoate in Plexippus paykulli (Araneae: Salticidae)

In the present study, effects of λ-cyhalothrin and emamectin benzoate on survival, locomotion, avoidance behaviour and growth of Plexippus paykulli Savigny Et Audouin, 1827 were studied. P. paykulli was found highly susceptible against the recommended field rate concentration of λ-cyhalothrin. The pesticide affected survival, locomotion and growth of the spiders. On the other hand, emamectin benzoate showed a negligible effect on spiders survival. However, emamectin benzoate significantly affected the locomotion and growth of P. paykulli. It is concluded that although emamectin benzoate is less toxic than λ-cyhalothrin for P. paykulli, it cannot be recommended for IPM programme.

Lethal time of insecticides on the predator mite Neoseiulus fallacis (Acari: Phytoseiidae) following topical exposure

AbstractNeoseiulus fallacis (Garman) (Acari: Phytoseiidae) is an efficient predator of the European red mite (ERM) (Panonychus ulmi (Koch); Acari: Tetranychidae) in Michigan, United States of America apple orchards and an important part of integrated pest management. Four reduced-risk insecticides (acetamiprid, spinetoram, chlorantraniliprole, and novaluron) and two conventional insecticides (esfenvalerate and carbaryl) were tested against N. fallacis for topical toxicity effects. Bioassays using a Potter spray tower were conducted to measure the topical toxicity of compounds when applied at field rate concentrations to N. fallacis. Lethal time was measured for adult N. fallacis at 4, 24, 48, 72, and 96 hours after treatment. Carbaryl and esfenvalerate showed the highest levels of toxicity to adult N. fallacis with shortest lethal time values (LT50) whereas the reduced risk insecticides novaluron, acetamiprid, spinetoram, and chlorantraniliprole were nontoxic. This study provides important information to apple growers regarding direct lethal effect of insecticides on predator mites and its implications to integrated mite management.

Susceptibility of two diamondback moth parasitoids, Diadegma insulare (Cresson) (Hymenoptera; Ichneumonidae) and Oomyzus sokolowskii (Kurdjumov) (Hymenoptera; Eulophidae), to selected commercial insecticides

In summer and fall 2004, insecticide toxicity bioassays were conducted on adults of Diadegma insulare and Oomyzus sokolowskii , two important parasitoids of diamondback moth, Plutella xylostella in the southeastern United States. The toxicity bioassay utilized a cabbage leaf dip method and serial dilution concentrations of various labeled insecticides on crucifer crops. Results showed that all insecticide treatments, including spinosad, indoxacarb, esfenvalerate, methomyl, acetamiprid, acephate, emamectin benzoate, and methoxyfenozide were toxic to the adult stage of D. insulare or O. sokolowskii or both. The broad-spectrum insecticides esfenvalerate, methomyl, and acephate as well as the more IPM-compatible insecticides, spinosad, indoxacarb, and emamectin benzoate at their field rate concentrations resulted in 100% mortality to either D. insulare or O. sokolowskii or both after 72 h of exposure. Moreover, LC 50 values for all of these insecticides were only a fraction (<2%) of the actual field rate concentration. The neonicotinoid, acetamiprid was less toxic than the other insecticides but still killed 77% of D. insulare adults and 91% of O. sokolowskii adults after 72 h of exposure. The insect growth regulator, methoxyfenozide, though considerably less toxic than the other insecticides based on LC 50 levels, still resulted in substantial (62%) mortality of O. sokolowskii adults after 72 h. Results of these studies suggest that field applications of any of the aforementioned insecticides would impact biological control of diamondback moth.

Developing an Ecotoxicological Testing Standard for Predatory Mites in Australia: Acute and Sublethal Effects of Fungicides on &lt;I&gt;Euseius victoriensis&lt;/I&gt; and &lt;I&gt;Galendromus occidentalis&lt;/I&gt; (Acarina: Phytoseiidae)

Abstract Laboratory bioassays for testing the effect of agrochemicals on Euseius victoriensis (Womersley) and Galendromus occidentalis (Nesbitt) on detached leaves of Glycine max (L.) (soybean) and Phaseolus vulgaris L. (French bean) were developed. The tests allowed standardized comparisons between mite species and leaf substrates, under “worst-case scenario” exposure, comparable with commercial pesticide application. Young juveniles, along with their initial food and the entire water supply, were sprayed to the point of runoff by using a Potter spray tower. The highest registered field rate concentration used on French bean was adjusted to deliver the same pesticide dose per higher runoff point spray volume on soybean. Cumulative mortality was assessed at 48 h, 4 d, and 7 d after spray application. Fecundity was assessed for 7 d from the onset of egg lay. Boscalid (Filan 500 WG), dithianon (Delan 700 WG), and kresoxim-methyl (Stroby 500 WG) caused no significant 7-d mortality or fecundity reduction to G...

Developing an ecotoxicological testing standard for predatory mites in Australia: acute and sublethal effects of fungicides on Euseius victoriensis and Galendromus occidentalis (Acarina: Phytoseiidae).

Laboratory bioassays for testing the effect of agrochemicals on Euseius victotiensis (Womersley) and Galendromus occidentalis (Nesbitt) on detached leaves of Glycine max (L.) (soybean) and Phaseolus vulgaris L. (French bean) were developed. The tests allowed standardized comparisons between mite species and leaf substrates, under "worst-case scenario" exposure, comparable with commercial pesticide application. Young juveniles, along with their initial food and the entire water supply, were sprayed to the point of runoff by using a Potter spray tower. The highest registered field rate concentration used on French bean was adjusted to deliver the same pesticide dose per higher runoff point spray volume on soybean. Cumulative mortality was assessed at 48 h, 4 d, and 7 d after spray application. Fecundity was assessed for 7 d from the onset of egg lay. Boscalid (Filan 500 WG), dithianon (Delan 700 WG), and kresoxim-methyl (Stroby 500 WG) caused no significant 7-d mortality or fecundity reduction to G. occidentalis or E. victoriensis compared with controls, and are classified as harmless to both species. Mancozeb (Mancozeb 750 WG) was highly toxic to both species, resulting in severe mortality and fecundity reduction and is considered incompatible with integrated pest management programs that use these species. Metiram (Polyram 700 WG) was highly toxic to E. victoriensis but only moderately toxic to G. occidentalis. Analyses of mortality proportions, including, and excluding unaccounted escapees, produced the same results. Test standardization on leaf substrates provides an alternative approach to standardization via residue on glass used by International Organisation for Biological and Integrated Control or Noxious Animals and Plants/West Palaearctic Regional Section regulatory testing in the European Union.

Sublethal effects of esfenvalerate residues on pyrethroid resistant Typhlodromus pyri (Acari: Phytoseiidae) and its prey Panonychus ulmi and Tetranychus urticae (Acari: Tetranychidae).

The effect of residues of esfenvalerate on oviposition of the resistant strain of the predatory mite Typhlodromus pyri and its main prey, European red mite Panonychus ulmi and two-spotted spider mite Tetranychus urticae, were investigated. T. pyri showed a significant linear reduction in oviposition after 24 h in the presence of increasing levels of esfenvalerate residue applied at the field rate. Furthermore, when given a choice, T. pyri preferred to lay eggs on residue-free surfaces. Of the two prey species, only P. ulmi showed significant avoidance of increasing levels of residues of the field rate concentration of esfenvalerate, as measured by runoff mortality, however both P. ulmi and T urticae, when given a choice, showed a preference for esfenvalerate-free surfaces. As with the predatory mite T. pyri, both prey species showed a significant linear reduction of oviposition with increasing esfenvalerate residues and a preference to lay eggs on esfenvalerate-free surfaces. Esfenvalerate residues as high as 15X field rate were not repellent to pyrethroid-resistant T. pyri. The possible effects of these sublethal effects on predator-prey dynamics and implications for integrated mite control programmes in apple orchards are discussed.

Laboratory Evaluations of Insecticides Against Crb Adults, 1996

Abstract Field collected adults of CRB were held in a ventilated cage with an adequate food supply for two days prior to beginning the bioassay. Water based mixtures of each treatment were prepared in glass beakers based on field-rate concentrations at 100 gpa. Silwett L-77 at 8.0 oz./lOO gal solution was added to each solution to facilitate wetting and each mixture was mixed thoroughly. Treatments were evaluated using the leaf dip method. Taro (Colocasia esculenta) leaves were field collected and held in the refrigerator until they were ready to use. Three leaves were completely immersed in each of the spray mixtures and allowed to air dry. The treated leaves were cut into 5 cm2 pieces and placed into ventilated plastic petri dishes. Five adult CRB were introduced into the dish. Each treatment was replicated 10 times. Mortality was assessed at 24-hour intervals. At each assessment, leaf pieces were changed with a fresh leaf piece cut from the remaining treated leaves to assure a fresh food supply.

Laboratory Evaluation of a Neem Product Against DBM Larvae, 1995

Abstract Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot containing approximately 10 cabbage plants in the 5 true leaf seedling stage was inverted and dipped in a test insecticide mix for about 30 sees for complete coverage. The dipped plants were allowed to air dry. For each dip, 1 liter insecticide mix was prepared based on field rate concentrations of 100 gal/acre. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii and Kamuela, Hawaii were used. Ten late 2nd instars were placed on each leaf. Fresh leaves from the original treated plant were added every two days. The number of dead larvae was counted at 24-hour intervals. Larvae were recorded as dead when there was no movement when probed.

Laboratory Evaluation of Two IGR Insecticides Against DBM Larvae, 1995

Abstract Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot containing approximately 10 cabbage plants in the 5-7 true leaf seedling stage was inverted and dipped in a solution of the test materials for about 30 sees for complete coverage. The dipped plants were allowed to air dry. For each dip, 1 liter solution of the test material was prepared based on field rate concentrations of 100 gal/acre. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii and Kamuela, Hawaii were used. Ten 2nd instars were placed on each leaf. Each treatment was replicated 10 times. Xentari was used as the treated check. The number of dead larvae was counted at 24-hour intervals. Larvae were recorded as dead when there was no movement when probed. Leaves were changed every other day with fresh leaves from the previously treated pots.

Laboratory Evaluation of Fipronil Against DBM Larvae, 1995

Abstract Treatments were evaluated using the leaf dip method. Head cabbage was seeded in community pots. Each pot containing approximately 10 cabbage plants in the 5-7 true leaf seedling stage was inverted and dipped in a test insecticide mix for about 30 sees for complete coverage. The dipped plants were allowed to air dry. For each dip, 1 liter insecticide mix was prepared based on field rate concentrations of 100 gal/acre. Leaves from treated plants were detached and placed in a ventilated plastic petri dish. DBM larvae from a laboratory colony that originated from individuals collected from a cabbage field at Kula, Hawaii and Kamuela, Hawaii were used. Ten 3rd instars were placed on each leaf. Each treatment was replicated 10 times. The number of dead larvae was counted at 24-hour intervals. Larvae were recorded as dead when there was no movement when probed.

Toxicity and repellency of some biorational insecticides to Bemisia argentifolii on tomato plants

AbstractA mineral oil, an insecticidal soap, and a plant‐derived surfactant were compared with a broad‐spectrum pyrethroid for residual toxicity and repellency to silverleaf whitefly, Bemisia argentifolii Bellows &amp; Perring (Homoptera: Aleyrodidae) on tomatoes (Lycopersicum esculentum Miller, cv. Lanai) under greenhouse and laboratory conditions. The materials tested were: Sunspray oil (a mineral oil), M‐Pede (an insecticidal soap), Nicotiana gossei extract (a sucrose ester surfactant), Garlic Barrier (repellency only), and the pyrethroid bifenthrin (Brigade 10WP), with water as a control. For toxicity studies, whiteflies were confined on leaves which had been dipped in solutions of 0.5 ×, 1 × and 2 × field rate concentrations. Insecticide residues were compared when the leaves were wet and dry. Adult mortalities were greatest with bifenthrin and Sunspray oil, followed by M‐Pede, N. gossei extract and water. Mortality from dry residue of lower rates of bifenthrin and Sunspray oil was greater than mortality from wet residues, whereas M‐Pede lost all activity upon drying. Dual and multiple choice tests for repellency were carried out in the greenhouse or laboratory by spraying plants or individual leaves to runoff with 1 × field concentrations. Bifenthrin and Sunspray oil repelled B. argentifolii adults for up to 7 and 5 days, respectively, followed by M‐Pede and extract of N. gossei, whereas Garlic Barrier was not significantly different from the water control in all tests. Numbers of whitefly eggs were significantly reduced on bifenthrin and Sunspray oil‐treated leaves, whereas egg numbers in other treatments were not different from water. Sunspray oil as a dip proved to be at least as effective as the synthetic pyrethroid for whitefly control. A multiple‐choice leaf‐wheel proved to be a useful device to quickly evaluate repellent effects of several different insecticides to whitefly.

Mineralization of 14C-labelled rice straw in aerobic and anaerobic clay soils as influenced by insecticide treatments

The mineralization of 14C-labelled rice straw in a clay soil under aerobic and anaerobic conditions as influenced by hexachlorocyclohexane, carbaryl and carbofuran was studied for 40 days. More mineralization of 14C-labelled rice straw was observed in aerobic than in anaerobic soil. HCH at 10-times field rate concentration only inhibited 14CO 2 evolution in aerobic soil after 3-days incubation. In general, insecticides applied to soil at normal field rates and 10-times field rates had no effect on either the amount of 14CO 2 evolved or 14C-residues remaining in the soil.