The parameters of comparative evaluation of insecticidal activity of preparations in aerosol containers

On the basis of experimental data, the authors present a group of parameters for the purpose of unification of comparative evaluation of the insecticidal effect of preparations in aerosol containers designed for combatting flying and non-flying domestic insects. The advisability of evaluation of the effect of the preparations for combatting flying insects according to the concentration of insecticides ensuring death of flies in the course of 15 min and the corresponding expenditure of the mixture has been substantiated. Preparations designed for combatting non-flying insects should be evaluated according to the coefficients of acute action, ovicidal and residual effects. To facilitate analysis and evaluation of the preparations in aerosol containers, the authors propose their classification according to the parameters of the insecticidal effect. Classification of the preparations under study according to their parameters is presented. It has been demonstrated that compositions containing pyrethroids and their mixtures with DDVP--Neofos, Neofos-2 and Pif-Paf are the most efficient.     

Contamination affects the performance of insecticidal baits against German cockroaches (Dictyoptera: Blattellidae)

The effects of contamination of insecticidal bait formulations, by using mint oil and silica aerogel, were evaluated in a series of laboratory experiments against the German cockroach, Blattella germanica (L.). Bait consumption at 3 d for uncontaminated baits ranged from 0.01 g for Avert dust to 0.399 g for Combat dry bait with hydramethylnon presented in a station. LT50 values for uncontaminated gel bait deposits ranged from 0.4 d for PreEmpt containing imidacloprid to 4.1 d for Maxforce containing hydramethylnon. As a group, significantly more gel bait was consumed than solid formulations even when both formulations had similar concentrations of the same active ingredient. As a result, gel baits were significantly more toxic than solid formulations. Application of mint oil directly to bait deposits significantly decreased bait consumption and increased overall LT50 values. When bait formulation types were examined individually, there was no difference in consumption or toxicity between contaminated and uncontaminated gel formulations. Contaminated solid baits, however, had significantly greater LT50 values and less consumption than uncontaminated solid baits. Gel formulations probably absorbed the contaminants and removed them from the surface of the bait deposits resulting in normal bait consumption and toxicity. Gel and solid bait deposits, inside plastic exposure stations or alone with no station and placed onto mint oil-contaminated substrates, had significantly lower bait consumption and greater LT50 values than baits placed on uncontaminated substrates. Contamination of a baited area is more likely than contamination of just the bait deposit and therefore a more realistic test of the effects of contamination on bait performance. The importance of contamination to the performance of cockroach baits is discussed.     

Cultural and insecticidal control of Thrips tabaci on onions in the Sudan

Onion thrips (Thrips tabaci) is the major pest of onions in the Sudan. In the Gezira Scheme onions are normally transplanted between October and January when the thrips population is very low. Later, thrips commence to breed. Early transplanted onions were well established before infestations became severe and, without the need for insecticidal control, produced significantly higher yields. Onions transplanted later, when thrips began to multiply, produced lower yields. Depending on the duration and intensity of infestation three to five sprays applied at fortnightly intervals were required to control thrips on the late transplanted crop. The effect of spray frequency on the development and yield of onions was investigated and the response found to be solely due to the extent of thrips control achieved. The toxicant itself had no effect on growth. Although the leaves were unaffected by the various treatments, spraying when most thrips were present increased fresh and dry leaf weights, bulb weight and, in the Hudeiba cultivar, the proportion of flowering plants. With the late-transplanted crop, light infestations led to yield losses of at least 39% whilst severe thrips attacks reduced the crop by 57%.     

Effectiveness of education for control of house dust mites and cockroaches in Seoul, Korea

We evaluated the efficacy of health education in reducing indoor arthropod allergens in Seoul. The mite control measures comprised the use of mite-proof mattress and pillow coverings, regular washing of potentially infested materials, maintenance of a low humidity, removal of carpets, and frequent vacuum cleaning. Cockroach control measures included trapping, application of insecticides, and protecting food. Of 201 homes enrolled in October 1999, 63 volunteers were included in a 2-year follow-up survey between April 2000 and January 2002. Before intervention, the density of mites/g of dust varied greatly; 27.1/g in childrenos bedding, 20/g in adult bedding, 7.2/g on the floors of childrenos bedrooms, 6.8/g in sofas, 5.9/g on the floors of adultos bedrooms, 3.9/g on living room floors, 3.7/g in carpets, and 1.9 mites/g on kitchen floors. The predominant mite species and house percentages infested were; Dermatophagoides farinae 93%, D. pteronyssinus 9%, and Tyrophagus putrescentiae 8%. Comparing 1999 and 2001 infestations, before and after 25 mo of education, mite abundance was reduced by 98%, from 23.7 to 0.57 mites/g of dust. In 1999, cockroaches were detected in 62% homes: 36% Blattella germanica and 35% Periplaneta spp., including 9% double infestations of B. germanica and P. americana. Following intervention, cockroach infestation rates decreased to 22% of houses in 2000 and 23% in 2001. We conclude that continuous and repetitive health education resulted in the effective control of domestic arthropods.     

Effects of moisture on the toxicity of inorganic and organic insecticidal dust formulations to German cockroaches (Blattodea: Blattellidae)

Toxicity of boric acid (40-99% [AI]), silica gel, eugenol, and deltamethrin dust formulations to adult male German cockroaches, Blattella germanica (L.), was evaluated at five different relative humidities ranging from 0 to 100% and in the presence of 0 to 1 ml of water. Victor boric acid dust was generally the most toxic boric acid formulation at all relative humidities, despite having the lowest percentage (40%) of boric acid; however, this was the only formulation to have sucrose and other edible ingredients. There was no consistent effect of relative humidity on dust toxicity; LT50 values of Roach Prufe (98% boric acid), Victor, and Drione (silica gel and synergized pyrethrins) increased significantly linearly with relative humidity, whereas other formulations were unaffected. The LT50 values of all boric acid-based dust formulations declined exponentially when wetted with increasing volumes of water. Water did not affect the toxicity of deltamethrin and eugenol dusts, but it caused a linear decline in toxicity of silica gel (Dri-Die). The toxicity of a formulation containing silica gel and synergized pyrethrins (Drione) increased exponentially with increasing amounts of water. Moisture in the form of relative humidity does not strongly affect the toxicity of most insecticidal dust formulations. Presence of water, however, increases the toxicity of boric acid dusts and Drione. Toxicity of the hydrophobic deltamethrin (DeltaDust) and eugenol (EcoPCO D) dusts were unaffected by water.     

Comparison of effects of octopamine and insecticidal essential oils on activity in the nerve cord, foregut, and dorsal unpaired median neurons of cockroaches

Essential oil constituents were tested for their neurophysiological effects in Periplaneta americana and Blaberus discoidalis. Eugenol depressed spontaneous and stimulus-evoked impulses recorded extracellularly in the abdominal nerve cord, with an almost complete block of spikes at 2 x 10(-3) M. Geraniol and citral had similar depressive effects but increased spontaneous firing at lower doses (threshold 2.5 x 10(-4) M). Similar effects occurred in dorsal unpaired median (DUM) neurons, recorded intracellularly in the isolated terminal abdominal ganglion of P. americana. Spontaneous firing was progressively reduced by increasing concentrations of eugenol, whereas geraniol and citral produced biphasic effects (excitation at 10(-4) M, depression at 2 x 10(-3) M). All three oils decreased excitability of silent DUM neurons that were depolarised by applied current, but eugenol (at 10(-3) M) also changed the firing pattern from single spikes to bursts driven by plateau potentials. All oils reduced spike undershoot. Low doses of citral and geraniol (threshold ca. 10(-4) M) reversibly increased the frequency of spontaneous foregut contractions and abolished them at 2 x 10(-3) M (together with response to electrical stimulation). Eugenol reversibly reduced spontaneous activity at 10(-4) M and above. Eugenol has been reported to exert its insecticidal properties via a low-dose activation of octopamine receptors. In our studies, however, octopamine was found to have opposing effects to eugenol on DUM neurons and foregut activity (excitatory in both). Furthermore, eugenol did not affect the response to octopamine in DUM neurons. These results suggest that reported effects of eugenol were on a different sub-type of octopamine receptor.     

Elaboration of a semiautomated enzymatic analyzer of glucose for the control of biosynthesis of antibiotics

The results of developing a semiautomatic apparatus with oxygen detection for enzymatic control of glucose concentration are presented. The design of a glucose sensitive electrode is based on an oxygen probe and a membrane with immobilized glucose oxidase. Materials for the probe were chosen and the operating conditions for measuring temperature, pH, linear agitation velocity and other parameters were optimized. The semiautomatic analyzer was constructed and its main characteristics were studied. The results of the apparatus testing during biosynthesis of various antibiotics are presented. It was shown that the required glucose concentration in the cultivation medium was provided for any specific circumstances in relation to the carbohydrate source.     

Persistence and distribution of insecticidal seed-dressings for control of the wheat bulb fly, Leptohylemyia coarctata

Samples of plants and soil from two experimental sites, one clay loam and one peaty loam, were analysed chemically to try to explain differing results with γ-BHC and dieldrin seed-dressings applied to control wheat bulb fly on different soil types, and to suggest reasons for patchy plant stands and occasional failure to control the pest. Seed dressed with dieldrin yielded more than untreated seed on both sites, whereas seed treated with γ-BHC yielded as much as seed treated with dieldrin on the clay site, but it yielded less than untreated seed on peat. The chemical analyses showed that the poor performance of γ-BHC on the peat site could not be explained by its failure to persist, because the soil still contained considerable quantities of γ-BHC at the time of insect attack. Possible reasons may be sorption of the poison by organic matter making it less available, and deeper sowing, permitting larvae to reach the plants without prolonged contact with the insecticide. Bayer 38156 (O-ethyl S-p-tolyl ethyl phosphonodithioate) and trichloro-nate (O-ethyl O-2,4,5-trichlorophenyl ethyl phosphonothionate) persisted in soil long enough and were sufficiently toxic to wheat bulb fly to suggest that organophosphorus compounds might provide alternatives to chlorinated hydrocarbon insecticides for control of the fly. Analyses made on seeds dressed at the laboratory for the experiment showed that the amounts of insecticide on seeds were smaller than expected and that the amounts on individual seeds differed greatly. Of ten samples of seeds dressed commercially with y-BHC, three carried very little insecticide, and the variations in the other seven samples were greater than with experimentally applied dressings.     

Field trial on the control effect of fipronil bait against German cockroaches

A field trial on the control effect of fipronil poison bait against German cockroaches (Blatella germanica) was carried out at different restaurant types in Sinchon, Seoul, Republic of Korea. Monitoring was performed applying food baited traps for 2 days per week. Reduction rates of German cockroaches by applying fipronil baits were 90.9% at Korean restaurants, 96.4% at Chinese restaurants, and 89.4% in beer hall kitchens after 4 weeks of the treatment. Overall average of the reduction rate was 93.9%. As the natural reduction rate at untreated restaurants was 11.5% after 4 weeks, a correction of the average reduction rate by applying the Abbot formula was 93.1%.     

Effectiveness of supervised control practices in lowering population densities of synanthropic flies on poultry ranches

Significant reductions of the average densities of 7 Diptera:Musca domestica L.,Muscina stabulans (Fallen),Fannia canicularis (L.),F. femoralis (Stein),Ophyra leucostoma (Wiedemann),Stomoxys calcitrans (L.), andPhaenicia spp. were attained over a 20-month period on poultry ranches that were under supervision in southern California by favoring the natural increase of predatory and scavenger arthropods and by periodic inoculative releases of 4 parasitic Hymenoptera. The importance of a long range management plan is emphasized. Releases of parasitic Hymenoptera during spring months had an apparent greater direct effect on fly population reduction than did similar releases in the summer. Autumn releases were not evaluated through a temporary ban on sampling breeding habitats in the wake of a Newcastle Disease outbreak. The importance of habitat stability and exotic importations of beneficial species are discussed.     

Residual effectiveness of insecticides for control of German cockroaches (Dictyoptera: Blattellidae) in food-handling establishments

Residual effectiveness of insecticides was compared for two treatment methods at various sites within two commercial kitchens. For all sites and insecticides, German cockroach, Blattella germanica (L.), mortality was greatest for treatments of cracks and crevices than for treatments of exposed surfaces. Mortality at the dishwashing site was lower than at all other sites. We attributed reduced mortality at the dishwashing site to a higher vapor pressure deficit. Mortality and the amount of insecticide residue recovered from treated surfaces were closely correlated. These data demonstrate that careful placement of residual insecticide treatments will influence their effective longevity.     

A review of the hymenopterous natural enemies of cockroaches with emphasis on biological control

The biology and control potential of hymenopterous natural enemies of cockroaches in the familiesAmpulicidae, Evaniidae, Pteromalidae, Eulophidae, Eupelmidae, andEncyrtidae were reviewed. Emphasis was placed on parasitoids of major domiciliary cockroach species, especially those that have had experimental usage in integrated pest management programs. The most promising parasitoids wereAprostocetus hagenowii (Ratzeburg) againstPeriplaneta species, andComperia merceti (Compere) againstSupella longipalpa (F.). Future research should focus on practical augmentation techniques that will be compatible with other control methodologies in the urban environment.      

Geographic variation in color of the synanthropic Blue rock pigeon

Variation in plumage color was studied in 211 populations of the blue rock pigeon (Columbia livia) from various geographic zones. The frequency distribution of three common and three rare phenotypes and an interspecific hybridization zone of C. livia and C. rupestris were described. Different conditions of the origin of the urban populations of blue rock pigeon and consequent high genetic heterogeneity of this species were revealed. The key aspect of color polymorphism in blue rock pigeon is synanthropization, i.e., anthropogenic evolution.