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PubMed1999

Cytochrome P450 MA expression in insecticide-resistant German cockroaches (Dictyoptera: Blattellidae).

Cytochrome P450 monooxygenases are detoxification enzymes commonly involved in insecticide resistance by insects. Recently, an overexpressed form of this enzyme, P450 MA, was purified from an insecticide-resistant strain of German cockroach, Blattella germanica (L.), and polyclonal antisera (anti-P450 MA) was produced. To test hypotheses that the overexpressed condition of P450 MA has evolved in > 1 geographic location and that P450 MA might be involved in insecticide resistance to specific insecticides, investigations were conducted using 4 insecticide-resistant and 1 susceptible German cockroach strains. In western blots that used anti-P450 MA antiserum as a probe, substantial differences in expression of P450 MA were observed. Strains showing the highest P450 MA expression had both the highest tolerance to the organophosphate insecticide chlorpyrifos and cytochrome P450-mediated demethylation activity. Results support the hypothesis that cytochrome P450 MA is potentially overexpressed in insecticide-resistant populations on a global scale.

Animals↗
PubMed1963

RUMEN BACTERIAL AND PROTOZOAL RESPONSES TO INSECTICIDE SUBSTRATES.

Insecticides containing organophosphate, chlorinated hydrocarbon, and carbamate were tested with bovine ruminal ingesta fractions. Rumen bacteria exposed to insecticide levels of 0 to 500 ppm in rumen fluid for 4 hr were inoculated into rumen fluid-starch feed extract medium. No apparent significant bacterial count inhibitions were noted. Also, when insecticides were used as carbon sources at concentrations of 500 ppm in carbohydrate-limited media, no increases in bacterial counts were indicated. Warburg manometric data showed that paraffin oil-Triton X-155 preparations of dimethoate, Diazinon, lindane, Thiodan and Sevin stimulated gas production in holotrich protozoa. Entodinium simplex, an oligotrich, produced less gas with insecticide substrates per unit of dry weight than did an Isotricha sp. Rumen bacteria and plant debris fractions from ruminal ingesta provided with insecticides did not give increased manometric responses over the endogenous control vessels. Washed suspensions of I. intestinalis produced volatile fatty acids in excess of the endogenous suspensions when provided insecticide substrates. Thiodan dissimilation by I. intestinalis was followed colorimetrically with 15% loss in substrate in 1 hr of incubation at 39 C. Diazinon-C(14) substrate uptake was demonstrated with suspensions of E. simplex and I. intestinalis. Rumen ciliates are suggested as a possible means for screening out useful insecticides susceptible to microbial dissimilation for use on forage and other cattle-feed crops.

Animals↗
PubMed2002

Impact of an insecticide resistance strategy for house fly (Diptera: Muscidae) control in intensive animal units in the United Kingdom.

A strategy for house fly (Musca domestica L.) control in intensive animal units in the United Kingdom was proposed by the Pesticide Safety Directorate (PSD) of the Ministry of Agriculture, Fisheries and Food in 1993. An advice leaflet was circulated to farmers, and label recommendations for insecticides used to control house flies were altered to prevent their long-term and frequent use. A study was carried out between 1996 and 1998 to gather data on insecticide use and resistance in house fly populations and compared with results from a study carried out in 1990-1992 to assess the impact of the 1993 label recommendations. As in the 1990-1992 study, resistance to methomyl, azamethiphos and pyrethrins + piperonyl butoxide was assessed. Larvicide tests with cyromazine, which had recently been released in the United Kingdom, were also included in this study. Most of the farmers claimed to have received and read the PSD insecticide advice leaflet, and half claimed to have altered insecticide treatments as a result. Comparing results for insecticides used before and after 1993, the proportion of farmers claiming to have used each of the insecticides had decreased. However, there had been no amelioration in resistance to synergised pyrethrins, and the number of house fly populations with reduced response to the insecticide baits had increased between 1990-1992 and 1996-1998. All the house fly populations tested were fully susceptible to cyromazine. There is an urgent need, therefore, to devise new strategies and particularly to minimize the risk of selecting for resistance to cyromazine.

Animals↗
PubMed2005

Distributing insecticide-treated bednets during measles vaccination: a low-cost means of achieving high and equitable coverage.

OBJECTIVE: To achieve high and equitable coverage of insecticide-treated bednets by integrating their distribution into a measles vaccination campaign. METHODS: In December 2002 in the Lawra district in Ghana, a measles vaccination campaign lasting 1 week targeted all children aged 9 months-15 years. Families with one or more children less than five years old were targeted to receive a free insecticide-treated bednet. The Ghana Health Service, with support from the Ghana Red Cross and UNICEF, provided logistical support, volunteer workers and social mobilization during the campaign. Volunteers visited homes to inform caregivers about the campaign and encourage them to participate. We assessed pre-campaign coverage of bednets by interviewing caregivers leaving vaccination and distribution sites. Five months after distribution, a two-stage cluster survey using population-proportional sampling assessed bednet coverage, retention and use. Both the pre-campaign and post-campaign survey assessed household wealth using an asset inventory. FINDINGS: At the campaign exit interview 636/776 (82.0%) caregivers reported that they had received a home visit by a Red Cross volunteer before the campaign and that 32/776 (4.1%) of the youngest children in each household who were less than 5 years of age slept under an insecticide-treated bednet. Five months after distribution caregivers reported that 204/219 (93.2%) of children aged 9 months to 5 years had been vaccinated during the campaign; 234/248 (94.4%) of households were observed to have an insecticide-treated bednet; and 170/249 (68.3%) were observed to have a net hung over a bed. Altogether 222/248 (89.5%) caregivers reported receiving at least one insecticide-treated bednet during the campaign, and 153/254 (60.2%) said that on the previous night their youngest child had slept under a bednet received during the campaign. For households in the poorest quintile, post-campaign coverage of insecticide-treated bednets was 10 times higher than pre-campaign coverage of households in the wealthiest quintile (46/51 (90.2%) versus 14/156 (9.0%)). The marginal operational cost was 0.32 US dollars per insecticide-treated bednet delivered. CONCLUSION: These findings suggest that linking bednet distribution to measles vaccination campaigns may provide an important opportunity for achieving high and equitable coverage of bednets.

Adolescent↗
PubMed2002

Toxicity of biorational insecticides: activity against the green peach aphid, Myzus persicae (Sulzer).

The relationship between dose for each of four biorational insecticides (pyrethrins, neem extract, capsiacin extract, insecticidal soap) and mortality of the green peach aphid (Myzus persicae) was determined using a laboratory bioassay. These insecticides were toxic to aphids and paired mixtures of the insecticides provided synergistic activity as measured by aphid mortality under the laboratory bioassay conditions. Capsiacin extracts were found to provide low levels of mortality alone but acted synergistically in mixtures with the other insecticides and provided higher than expected levels of mortality. Activity as determined in the laboratory for each insecticide was not evident under field-use conditions in five separate experiments. Under field conditions and using common application methods, these insecticides did not provide significant levels of control of aphids.

Agriculture↗
PubMed2004

The discovery of pyridalyl: a novel insecticidal agent for controlling lepidopterous pests.

Synthesis of analogues of two compounds with known insecticidal activity, both of which contain a 3,3-dichloro-2-propenyloxy group, produced 2-(trifluoromethyl)-4-phenoxyphenyl 3,3-dichloro-2-propenyl ether, which had weak activity against lepidopterous larvae. Structural modifications around this lead compound led to the development of pyridalyl [Pleo, S-1812; 2,6-dichloro-4-(3,3-dichloroallyloxy)phenyl 3-[5-(trifluoromethyl)-2-pyridyloxy]propyl ether], which belongs to a new class of insecticides. Pyridalyl gives very good control of various lepidopterous and thysanopterous pests on cotton and vegetables, without phytotoxicity. It controls populations of Heliothis virescens F and Plutella xylostella (L) which are resistant to various currently used insecticides. It also produces unique insecticidal symptoms, so it may have a different mode of action from other existing insecticides. Pyridalyl is also less harmful than existing insecticides to various beneficial arthropods, so it should provide an important tool in IPM and insecticidal management programmes for the control of lepidopterous and thysanopterous pests. The first market introduction is expected in Japan and some Asian countries in the years between 2004 and 2005.

Animals↗
PubMed2004

Insecticidal activity of deoxypodophyllotoxin, isolated from Juniperus sabina L, and related lignans against larvae of Pieris rapae L.

In the course of screening for naturally occurring insecticides from plants from the northwestern part of China, a petroleum ether extract of Juniperus sabina L was found to show insecticidal activity against fifth-instar larvae of Pieris rapae L. From the extract, an insecticidal compound was isolated by bioassay-guided fractionation. The compound was identified as deoxypodophyllotoxin (1) by comparison of its spectroscopic characteristics with literature data. In bioassays, 1 showed antifeedant activity against fifth-instar larvae of P rapae at 0.05-1.00 g litre(-1) and its AFC50 (concentration for 50% antifeedant activity) values at 12 and 48h were 0.170 and 0.060 g litre(-1), respectively. In that concentration range, all treated insects died within 48 h after treatment and compound 1 showed delayed insecticidal activity. At 0.015-0.100 g litre(-1), 1 showed insecticidal activity, with an LC50 of 0.020 g litre(-1). The related compound deoxypicropodophyllotoxin (2), however, showed lower antifeedant and insecticidal activities than 1 in bioassay. This indicated that the trans-lactone ring is an important moiety for enhancing activity in these compounds. Comparison of the insecticidal activities of 1 and another related compound, podophyllotoxin (3), suggested that varying the substituent at C-4 is an exciting possibility for synthesizing more potent analogues.

Animals↗
PubMed1976

Insecticide movement following application to crevices in rooms.

The movement of chlorpyrifos and diazinon from cracks and crevices in empty dormitory rooms with and without forced air movement to houseflies and plates in non-target areas was studied. Aluminum pie plates in rooms with the high concentrations of an insecticide, no forced air movement, and at the earlier sampling interals contained more insecticide. Insecticides were not detectable at 48 hr. Increased housefly movement occurred simultaneously with the initiation of insecticide application in rooms with forced air and 1 min later in rooms with no forced air. Mortality of houseflies exposed during and at 5 hr after insecticide application was greater for males than females in all tests except one; at the high insecticide concentrations; and at successive time intervals through the 24-hr interval after their transfer from the treated rooms to holding rooms. Houseflies in cages near the ceiling, exposed to an insecticide, and forced air movement, exhibited greater mortality than those in cages on the floor, while the reverse was true for houseflies in rooms with no forced air movement.

Air Movements↗
PubMed2003

Reduction in the sex ratio of the progeny of a parasitoid wasp (Trichogramma brassicae) surviving the insecticide chlorpyrifos.

Due to the wide use of insecticides and their contribution to environmental pollution, the determination of their sublethal effects on the reproduction of parasitoids regulating pest populations is a necessity. In this work, sublethal effects of a lethal dose 20% of chlorpyrifos on the reproduction and the sex ratio of Trichogramma brassicae were assessed. The organophosphorus insecticide chlorpyrifos is one of the most used insecticides for agricultural and domestic purposes in a worldwide market. A decrease in the number of parasitized hosts was observed for females surviving the insecticide. Furthermore, while untreated females presented a very biased sex ratio in favor of daughters, the offspring of treated females surviving the insecticide presented an almost balanced sex ratio due to a decrease in the number of daughters. This decrease in sex ratio was interpreted to be resulting from a decrease in fertilized eggs due to the perturbation of nerve transmissions induced by the insecticide. These results highlight the need for considering not only the direct mortality induced by insecticides but also sublethal effects liable to modify important fitness traits involved in the dynamic of beneficial insect populations.

Animals↗
PubMed2000

Response of bronchiolar Clara cells induced by a domestic insecticide. Analysis of CC10 kDa protein content.

Clara cells are the most reactive to xenobiotics among the mammalian respiratory tract cells. In this report, the response of Clara cells to acute or repetitive exposure to a commercial insecticide was studied, correlating the changes in the cell ultrastructure with the intracellular content of CC10 kDa protein as quantified by immunocytochemical morphometry. After a single exposure to insecticide, Clara cells reveal great expansion of their volume which is accompanied by a remarkable proliferation of smooth endoplasmic reticulum, swelling of the mitochondria, and changes in the nucleus. Morphometric analysis of CC10 bronchiolar content showed significant increases in both the number of Clara cells and the immunostained areas in individual cells. By western blot, CC10 immunoreactive bands strongly increased in lungs after insecticide treatment, but they were only slightly higher than the control when the vehicle of the insecticide was tested. By repetitive exposure to the insecticide, the rat bronchiolar epithelium undergoes extensive alterations, particularly on Clara cells, the number of which is considerably reduced. The remaining Clara cells shrink in size and the typical dome-like cytoplasm is lost. Secretory granule release is no longer seen and the changes of their shape and secretory content reflect a marked degradation and condensation process. Repetitive exposures to the insecticide produced a severe blockage of the proteinopoietic activity, particularly on the synthesis of CC10. Results reported here reveal that the acute inhalation of a commercial insecticide produces hypertrophy of Clara cells, a significant augmentation of CC10 synthesis, and probably differentiation de novo of Clara cells, and morphological changes compatible with a detoxification process. By contrast, exposure for 5 days provoked a general inhibitory effect on Clara cell activity with the loss of cell capability to synthesize and secrete CC10 kDa protein.

Animals↗
PubMed1983

Teratogenic effects of cholinergic insecticides in chick embryos--IV. The role of tryptophan in protecting against limb deformities.

The mechanism by which organophosphate (OP) insecticides cause micromelia in embryonic chick limbs was examined using a tissue culture approach. Limb bud cells in micromass culture were assayed for their proliferative and chondrogenic activities, [3H]thymidine and 35SO4 = incorporation, respectively, into the trichloroacetic acid-insoluble constituents of the cell masses and/or the accumulation of 35S-labeled soluble macromolecular products in the culture medium. There was no obvious correlation between either the teratogenicity or toxicity of the insecticide in ovo and the inhibition of proliferation and chondrogenesis in vitro. In addition, nicotinamide, which prevents insecticide-induced micromelia in ovo, did not improve the proliferative and chondrogenic performance of insecticide-treated cells in culture. On the other hand, 2-pyridinealdoxime methochloride, which offers little or no protection against micromelia in ovo, did protect both the proliferative and chondrogenic activities of the limb bud cells in micromass culture. These observations suggest that the actions of the insecticides on the cells in culture are not the same as those that produce micromelia in ovo. L-Tryptophan antagonized OP insecticide-induced micromelia in the embryo. In micromass culture, a much greater concentration of tryptophan was needed to support the chondrogenic than the proliferative activities of the limb bud cells. Moreover, a greater concentration of tryptophan was needed to support the chondrogenic activities of the leg bud than the wing bud cells. These in vitro responses of the limb bud cells to tryptophan deprivation are analogous to the in ovo response of the limbs to the teratogenic OP insecticides. A possible explanation of the roles of tryptophan and nicotinamide in preventing the limb deformities is offered.

Animals↗
PubMed1995

Molecular biology of insecticide resistance.

The widespread use of insecticides has amounted to a large scale 'experiment' in natural selection of insects by chemicals of toxicological importance to humans. Specific examples in which the molecular basis of insecticide resistance has been studied in detail are presented here. The biochemical/physiological mechanisms of resistance can be categorized as target site insensitivity, increased metabolic detoxification and sequestration or lowered availability of the toxicant. These are achieved at the molecular level by: point mutations in the ion channel portion of a GABA receptor subunit (cyclodiene insecticides); point mutations in the vicinity of the acetylcholinesterase (AChE) active site (organophosphorus and carbamate insecticide resistance); amplification of esterase genes (organophosphorus and carbamate insecticides); mutations linked genetically to a sodium channel gene (DDT and pyrethroid insecticides); and yet uncharacterized mutations leading to the up-regulation of detoxification enzymes, such as cytochrome P450 and glutathione S-transferases (many classes of insecticides). In several cases, the selection of a precisely homologous mutation has been observed in different insect species.

Animals↗
PubMed1986

Management of acute childhood poisonings caused by selected insecticides and herbicides.

Most childhood exposures to insecticides and herbicides do not result in poisonings. Decontamination and observation are usually adequate treatments. The most frequent exposures involve carbamate and organophosphate insecticides. These compounds inhibit acetylcholinesterase, resulting in cholinergic signs that are reversible with atropine administration. Recent reports from poison control centers indicate that organophosphates have been associated with most of the serious childhood poisonings. Pralidoxime, a cholinesterase reactivator, must be administered along with atropine to patients with serious organophosphate poisoning, to reverse nicotinic receptor effects--in particular, respiratory paralysis. Although carbamates and organophosphates may cause clinically indistinguishable physical signs, pralidoxime therapy may be contraindicated for carbamate intoxications. In the event of a serious poisoning caused by a combination of organophosphate and carbamate insecticides, or by an unknown cholinergic agent, pralidoxime should not be withheld. Many organochlorine insecticides are restricted or are no longer available in the United States. CNS excitation and seizures, manifestations of organochlorine intoxication, can occur following ingestion or inappropriate application of the 1 per cent topical formulation of lindane used to treat scabies and lice. Treatment of such intoxication consists of decontamination measures and anticonvulsant administration. Pyrethrins are generally nontoxic in doses commonly ingested. Individuals with an allergic history may be at greatest risk for the most common adverse effects, contact dermatitis and hypersensitivity reactions. Of all insecticides or herbicides, paraquat is the most toxic. Any exposure to paraquat must be evaluated, even if several days have passed since the herbicide was ingested. Signs of pulmonary status deterioration usually portend a grave prognosis in paraquat poisoning. Despite in vitro toxicity similar to paraquat, diquat does not cause lung effects in human poisonings, and reported deaths have been from other causes. Poisoned patients who receive appropriate and timely treatment are virtually assured of complete recovery from most insecticide and herbicide poisonings. Deaths and long-term sequelae most often result from respiratory complications, which may occur as complications of the intoxication or from other constituents in the insecticide or herbicide formulation. Good supportive care with meticulous attention to, and anticipation of, respiratory complications is absolutely essential to prevent long-term sequelae or death from hypoxia.(ABSTRACT TRUNCATED AT 400 WORDS)

Absorption↗
PubMed2003

Insecticide-treated cattle against tsetse (Diptera: Glossinidae): what governs success?

The distributions of insecticide-treated cattle from sites in Tanzania and Zimbabwe were assessed from interviews with livestock owners, analysis of secondary livestock data and mapping technologies. The time-course of tsetse control operations at these sites were then simulated using a mathematical model that assumed diffusive movement and logistic growth in fly populations. A simulation of a tsetse control operation in Mudzi district, north-east Zimbabwe, was in accord with observations that the use of insecticide-treated cattle was unable to prevent substantial re-invasion of tsetse from Mozambique, consequent on the patchy distribution of cattle. The simulation was also consistent with the observed efficacy of a 10-km wide barrier of insecticide-treated targets deployed evenly at 4 km/(-2). Simulation of a control operation on Mkwaja Ranch in Tanzania was in accord with the observation that the use of insecticide-treated cattle reduced the tsetse population on the ranch by c. 90%. Insecticide-treated cattle were used to better effect in the Kagera Region of Tanzania. Simulation of this operation predicts that the deployment of 35,000 treated cattle in the area would result in > 99% control of the tsetse population, consistent with the observed decline, by 1-2 orders of magnitude, in cases of trypanosomiasis in the region. The greater success of the Kagera operation was due to the size and shape of the treated area and, particularly, to the restriction of re-invasion to 20% of the perimeter, compared with > 80% on Mkwaja. Simulation was used to assess how tsetse control could have been improved at Mkwaja. The results suggest that splitting herds into smaller, more numerous, units could have achieved some improvement but, in general, the disease problem would not have been solved by the use of insecticide-treated cattle alone. Only by deploying odour-baited targets in ungrazed areas, or in a 1-3-km barrier around the ranch, could substantially better control (99-99.9%) have been achieved. Sensitivity analyses of the Mkwaja simulation showed that the general conclusions were robust to assumptions regarding cattle distribution and the rates of fly movement and growth. Properly managed and appropriately applied insecticide-treated baits are powerful weapons for tsetse control but should not be used without regard to potential levels of re-invasion, consequent largely on considerations of the size and shape of the treatment area and the density and distribution of the baits.

Animals↗
PubMed2001

Insecticide residues in cotton crop soil.

Dimethoate, monocrotophos, triazophos, deltamethrin, cypermethrin and endosulfan were applied to a cotton crop soil located at Nurpur village, Punjab, India. The insecticides were applied sequentially at recommended dosages in cotton fields by foliar application in 1995, 1996 and 1998. Soil samples were collected from the cotton crop farms and extracted with acetone. The extracted material was analysed by a gas liquid chromatograph (GLC) equipped with an 63Ni electron-capture detector (ECD-63Ni). Recovery data was obtained by fortifying soil with insecticide. The average recoveries from the fortified soil samples were 76-92% for organophosphorous compounds and 90-98% for synthetic pyrethroids and organochlorines. The results showed that the insecticide residues under study were present in the range of 1.16 to 41.97 ng g(-1) d.wt.soil. The pattern of dissipation of the insecticides used was similar for the duration of the crop. Half lives of the insecticides ranged from 7 to 22 days. Except endosulfan none of the other insecticides used were leached below 15 cm. Endosulfan was found to be rapidly degraded in the soil and formed a sulfate metabolite. Persistence and dissipation pattern in soils with history of exposure to the insecticide compared to non-history soils were similar.

Chromatography, Gas↗
PubMed1992

Susceptibility of house flies (Diptera: Muscidae) and five pupal parasitoids (Hymenoptera: Pteromalidae) to abamectin and seven commercial insecticides.

Assays of five commercial insecticides applied as residual sprays at label rates to plywood indicated the most toxic insecticide overall for pteromalid parasitoids of house flies, Musca domestica L., was Atroban (permethrin), followed by Ciodrin (crotoxyphos), Rabon (tetrachlorvinphos), Ectrin (fenvalerate), and Cygon (dimethoate). Insecticide-susceptible house flies were susceptible to all five insecticides (mortality, 62-100%). Flies that were recently colonized from populations on dairy farms in New York were susceptible only to Rabon. Urolepis rufipes (Ashmead) was the most susceptible parasitoid species overall to these insecticides, followed by Muscidifurax raptor Girault & Sanders, Nasonia vitripennis Walker, Pachycrepoideus vindemmiae (Rondani), and Spalangia cameroni Perkins. Compared with susceptible flies, newly colonized flies showed moderate resistance to avermectin B1a (abamectin). Abamectin was more toxic to all of the parasitoids except N. vitripennis and S. cameroni than to newly colonized house flies when exposed for 90 min to plywood boards treated with 0.001-0.1% abamectin. Space sprays with Vapona (dichlorvos) killed all of the parasitoids and susceptible flies and 64% of the newly colonized flies when insects were placed directly in the path of the spray; mortality was substantially lower among flies and parasitoids protected under 5 cm of wheat straw. Space sprays with Pyrenone (pyrethrins) killed greater than 86% of all insects exposed to the spray path except for the newly colonized flies (1% mortality); mortality of insects protected under straw was low (less than 12%) except for S. cameroni (76%). Because responses of the five parasitoids to the different insecticides varied considerably, general conclusions about parasitoid susceptibility to active ingredients, insecticide class, or method of application were not possible.

Animals↗
PubMed1997

Susceptibility of stable flies (Diptera:Muscidae) from southeastern Nebraska beef cattle feedlots to selected insecticides and comparison of 3 bioassay techniques.

Insecticide susceptibility of field populations of stable flies, Stomoxys calcitrans (L.), was assayed using 3 exposure techniques: treated filter papers, treated glass petri dishes, and topical applications. Both topical applications and residual exposure to treated glass surfaces were suitable for testing susceptibility of stable flies to permethrin, stirofos, or methoxychlor. Residues on filter papers yielded inconsistent results with stirofos and methoxychlor. Significant concentration-mortality regression lines were generated with permethrin residues on filter papers, but approximately 1,000 times more insecticide was required to produce a toxic response when compared with permethrin residues on glass. Because of higher variability in response and the greater amount of insecticide required, residues on filter papers do not appear appropriate to test insecticide susceptibility in stable flies. Paired comparisons of field (F) and susceptible (S) stable flies resulted in field to susceptible ratios significantly > 1.0 only when the flies were treated topically, which suggests that topical application is more sensitive than residues on glass for the insecticides tested. Topical treatment with permethrin resulted in one FS(LD90) of 1.8-fold. Topical treatment with methoxychlor resulted in one FS(LD90) of 3.4-fold. However, the magnitude of these ratios is not larger than the significant differences observed within the susceptible laboratory colony from one generation to another. Intense exposure to insecticides is not known to have occurred in these field populations, indicating that the observed differences are the result of natural variation among stable fly populations and unrelated to prior selection with insecticides.

Animals↗
PubMed2003

Conserving vedalia beetle, Rodolia cardinalis (Mulsant) (Coleoptera: Coccinellidae), in citrus: a continuing challenge as new insecticides gain registration.

The effects of insecticides used for California citrus pest management were evaluated using larval and adult stages of vedalia beetle, Rodolia cardinalis (Mulsant). This predatory beetle is essential for control of cottony cushion scale Icerya purchasi (Williston) (Homoptera: Margarodidae) in San Joaquin Valley citrus. When adult beetles were exposed to treated citrus leaves, adult survival was significantly reduced by the foliar neonicotinoid imidacloprid and the pyrethroid cyfluthrin. Progeny production was significantly reduced by imidacloprid, cyfluthrin, fenpropathrin, and buprofezin. Buprofezin, pyriproxifen, and foliar imidacloprid also significantly reduced successful development of larvae into the adult stage. When vedalia stages were fed insecticide-treated cottony cushion scale reared on Pittosporum tobira (Thunb.) Ait, toxic effects were more severe than contact toxicity alone. Adult beetle survival was most profoundly reduced by the pyrethroids and to a lesser extent the foliar neonicotinoids acetamiprid and imidacloprid. Progeny production and larval development to adulthood were reduced by all insecticides but were most severely affected by pyriproxifen and the pyrethroids. Systemically applied neonicotinoids were toxic to vedalia larvae feeding on cottony cushion scale that had ingested these insecticides. These data demonstrate that IGRs, neonicotinoid insecticides, and pyrethroid insecticides have a significant, negative impact on vedalia beetles. Depending on the rate of insecticide used, the number and timing of applications, and the level of coverage of the tree, disruption of vedalia can be minimized. However, the situation is made difficult when pests such as citrus thrips Scirtothrips citri (Moulton) (Thysanoptera: Thripidae), forktailed bush katydid Scuddaria furcata Brunner von Wattenwyl (Orthoptera: Tettigoiniidae), or glassy-winged sharpshooter Homalodisca coagulata Say (Homoptera: Cicadellidae) require these pesticide treatments during periods of vedalia beetle activity.

Animals↗