Oviposition of resistant and susceptible strains of Drosophila melanogaster in the presence of deltamethrin

Oviposition of three strains of Drosophila melanogaster in the presence of deltamethrin was observed. These strains had different levels of physiological susceptibility to deltamethrin. Two-choice tests were conducted with couples of flies in petri-dish arenas containing two oviposition dishes. On the first day of the experiment, females were given a choice between a treated oviposition dish and an untreated control dish. On the second day of the experiment, two control oviposition dishes were given to females. Although individual females showed a tendency to aggregate their eggs in one of the dishes, control experiments demonstrated an overall equal distribution of eggs between the dishes. When one of the two oviposition dishes in the arena was treated with deltamethrin, the percentage of females ovipositing and the mean number of eggs laid by females were reduced, compared with control arenas. Females avoided the treated oviposition dish and laid significantly more eggs on the control dish. Furthermore, when the deltamethrin concentration was increased on the first day, female flies postponed their oviposition and laid significantly more eggs on the second day. The resistant strain, SR, demonstrated the same capacity to select the untreated site for oviposition as the susceptible strain, but it showed a smaller oviposition reduction and egg retention. The relationship between physiological and behavioural susceptibility to deltamethrin is discussed.     

Development and laboratory evaluation of chemically‐based baited ovitrap for the monitoring of Aedes aegypti

Aedes (Stegomyia) aegypti is considered to be the most important dengue vector worldwide. Studies were conducted to design and evaluate a chemically‐based baited ovitrap for monitoring Ae. aegypti under laboratory conditions. Several known chemical attractants and three types of ovitraps (ovitraps A, B, and C) were evaluated throughout the oviposition bioassays. Oviposition responses of gravid female Ae. aegypti were evaluated to n‐heneicosane, 3‐methylindole (skatole), 4‐methylphenol (p‐cresol), and phenol. Female Ae. aegypti were attracted to all the evaluated compounds. Among them, n‐heneicosane at a concentration of 10 ppm (mg/l), skatole from 50 to 1000 ppm, p‐cresol at 100 ppm, and phenol at 50 ppm showed a significant positive oviposition response. A blend of the four chemical attractants increased the oviposition response; 67% of the eggs were deposited in the treatment compared to the control. Female Ae. aegypti were signi?cantly more attracted to ovitrap A loaded with the four‐component synthetic blend compared to the standard ovitrap in the oviposition bioassays. The compound used in ovitrap A retained its attractant property for up to three days. The chemically‐based baited ovitrap may be considered as an option to be integrated during the monitoring of dengue virus vectors in México.     

Laboratory tests of the effects of p-cresol and 4-methylcyclohexanol on oviposition by three species of Toxorhynchites mosquitoes

Laboratory experiments tested the effects of p-cresol or 4-methylcyclohexanol at concentrations of 1, 10 and 50 ppm, on oviposition by the mosquitoes Toxorhynchites brevipalpis Theobald, Tx. amboinensis (Doleschall) and Tx. splendens (Wiedemann). A 5 + 5 ppm mixture of the two chemicals was also tested. All three species laid significantly more eggs in cups containing p-cresol, whereas only Tx. brevipalpis and Tx. amboinensis responded similarly to 4-methylcycohexonol and to the mixture of both chemicals. Tx. brevipalpis was, to a relatively limited degree, the most responsive of the three species. Ancillary experiments indicated that the chemicals were acting as attractants, causing more females to fly to treated cups. No stimulant effects were detected either in terms of the proportion of females that initiated oviposition flight (after flying to the cups) or in terms of the number of looping flights executed prior to ejection of an egg.     

The efficacy of four avermectins on the synanthropic mite Lepidoglyphus destructor under laboratory conditions

The effect of four avermectins on the population growth of pest mite Lepidoglyphus destructor was tested in laboratory experiments. The avermectins (abamectin, doramectin, emamectin-benzoate and ivermectin) of analytical purity were incorporated into an experimental diet at the same molar concentrations, ranging from 0.16 to 8 nmol/3 g of diet. Using an initial population of 50 mites, the population growth was recorded after 21 days at 85 % relative humidity and 25 °C; 12 repeats were performed per avermectin concentration and control. The diets containing the avermectins successfully suppressed the population growth of L. destructor. The EC(50) recalculated to ng of substance per g of diet showed different suppressive effects of the avermectins: doramectin (181 ng/g diet), abamectin (299 ng/g diet), emamectin-benzoate (812 ng/g diet) and ivermectin (992 ng/g diet). Of the tested avermectins, abamectin is registered for the control of phytophagous mites and ivermectin against parasitic mites, i.e., Psoroptes ovis. Although emamectin-benzoate and ivermectin were less effective on L. destructor, all of the tested avermectins are highly suitable compounds for the control of synanthropic mites.     

Lethal and sublethal effects of two new insecticides spirotetramat and flupyradifurone in comparison to conventional insecticide deltamethrin on Trichogramma evanescens (Hymenoptera: Trichogrammatidae)

The effects of three insecticides including deltamethrin, spirotetramat and flupyradifurone on pre-imaginal stages of Trichogramma evanescens Westwood (Hymenoptera: Trichogrammatidae) were investigated using dipping method. The mean emergence rate of T. evanescens when exposed to the recommended field concentrations of deltamethrin, spirotetramat and flupyradifurone were 62.8, 84 and 86.1%, respectively while 94.3% of the wasps emerged in the control group. According to the concentration–response experiments, the LC₅₀ values of deltamethrin, spirotetramat and flupyradifurone were 262.9, 274.8 and 334.8 ppm, respectively. The results indicated that lethal (LC₅₀) and sublethal (LC₃₀) concentrations of three tested insecticides significantly reduced the fecundity and longevity of T. evanescens. However, LC₃₀ of spirotetramat and flupyradifurone didn’t influence the oviposition duration of the wasps when compared with the control group. The gross reproductive rate (GRR), intrinsic rates of increases (r), net reproductive rate (R₀), and finite rate of increase (λ) were significantly lower in all the treated wasps in comparison with control. However, the mean generation time (T) was not affected by the sublethal concentrations of tested insecticides. According to our findings, all insecticidal treatments have adverse effects on the population of T. evanescens, notwithstanding sublethal concentration of flupyradifurone followed by spirotetramat were more compatible with adults T. evanescens in comparison with deltamethrin. However, further studies under the field conditions are required to confirm the results.     

Evaluation of the Activity of the Essential Oil from an Ornamental Flower against Aedes aegypti: Electrophysiology,Molecular Dynamics and Behavioral Assays

Dengue fever has spread worldwide and affects millions of people every year in tropical and subtropical regions of Africa, Asia, Europe and America. Since there is no effective vaccine against the dengue virus, prevention of disease transmission depends entirely on regulating the vector (Aedes aegypti) or interrupting human-vector contact. The aim of this study was to assess the oviposition deterrent activity of essential oils of three cultivars of torch ginger (Etlingera elatior, Zingiberaceae) against the dengue mosquito. Analysis of the oils by gas chromatography (GC)—mass spectrometry revealed the presence of 43 constituents, of which α-pinene, dodecanal and n-dodecanol were the major components in all cultivars. Solutions containing 100 ppm of the oils exhibited oviposition deterrent activities against gravid Ae. aegypti females. GC analysis with electroantennographic detection indicated that the oil constituents n-decanol, 2-undecanone, undecanal, dodecanal, trans-caryophyllene, (E)-β-farnesene, α-humulene, n-dodecanol, isodaucene and dodecanoic acid were able to trigger antennal depolarization in Ae. aegypti females. Bioassays confirmed that solutions containing 50 ppm of n-dodecanol or dodecanal exhibited oviposition deterrent activities, while a solution containing the alcohol and aldehyde in admixture at concentrations representative of the oil presented an activity similar to that of the 100 ppm oil solution. Docking and molecular dynamics simulations verified that the interaction energies of the long-chain oil components and Ae. aegypti odorant binding protein 1 were quite favorable, indicating that the protein is a possible oviposition deterrent receptor in the antenna of Ae. aegypti.     

Comparative evaluation of spinosad and phloxine B as toxicants in protein baits for suppression of three fruit fly (Diptera: Tephritidae) species

Spinosad and phloxine B are two more environmentally friendly alternative toxicants to malathion for use in bait sprays for tephritid fruit fly suppression or eradication programs. Laboratory tests were conducted to assess the relative toxicity of these two toxicants for melon fly, Bactrocera cucurbitae Coquillett; oriental fruit fly, Bactrocera dorsalis Hendel; and Mediterranean fruit fly, Ceratitis capitata (Wiedemann) females. Field tests also were conducted with all three species to compare these toxicants outdoors under higher light and temperature conditions. In laboratory tests, spinosad was effective at much lower concentrations with LC50 values at 5 h of 9.16, 9.03, and 4.30 compared with 250.0, 562.1, and 658.9 for phloxine B (27, 62, and 153 times higher) for these three species, respectively. At 16 ppm spinosad, LT50 values were lower for all three species (significantly lower for C. capitata and B. dorsalis) than 630 ppm phloxine B LT50 values. At 6.3 ppm spinosad, the LT50 value for C. capitata (3.94) was still significantly less than the 630 ppm phloxine B LT50 value (6.33). For all species, the 100 ppm spinosad concentrations gave LT50 values of < 2 h. In comparison among species, C. capitata was significantly more sensitive to spinosad than were B. cucurbitae or B. dorsalis, whereas B. cucurbitae was significantly more sensitive to phloxine B than were C. capitata or B. dorsalis. LC50 values were reduced for both toxicants in outdoor tests, with greater reductions for phloxine B than for spinosad for B. dorsalis and B. cucurbitae. Fly behavior, though, is likely to keep flies from being exposed to maximum possible outdoor light intensities. Comparable levels of population suppression for any of the three species tested here will require a much higher concentration of phloxine B than spinosad in the bait.     

Odor learning byLeptopilina boulardi,a specialist parasitoid (Hymenoptera: Eucoilidae)

We studied odor learning in Leptopilina boulardi,a specialist larval parasitoid of Drosophila melanogaster.The behavioral responses of differently experienced females to an artificial odor (Must de Cartier, Paris) were analyzed using a fourarmed airflow olfactometer. The responses of females with an oviposition experience in the presence of the perfume were compared with those of four control groups. As controls we used naive females, females with an oviposition experience in the absence of odor, females which had been previously exposed to perfume but without an oviposition experience, and females with an oviposition experience which also had been exposed to perfume but not at the same time. The results demonstrate that a specialist such as L. boulardican learn very well to respond to an artificial odor by associating this odor with a reward, i.e., an oviposition. The four control groups responded more or less in a similar way.     

Pyrethroid susceptibility and behavioral avoidance in Anopheles epiroticus,a malaria vector in Thailand

The physiological susceptibility to insecticides and the behavioral responses of four wild‐caught populations of female Anopheles epiroticus to synthetic pyrethroids (deltamethrin, permethrin, and alpha‐cypermethrin) were assessed. Test populations were collected from different localities along the eastern coast, Trat (TR), Songkhla (SK), and Surat Thani (ST) and one population from the western coast, Phang Nga (PN). Results showed that all four populations of An. epiroticus were susceptible to all three synthetic pyrethroids tested. Behavioral responses to test compounds were characterized for all four populations using an excito‐repellency test system. TR displayed the strongest contact excitation (‘irritancy’) escape response (76.8% exposed to deltamethrin, 74.1% permethrin, and 78.4% alpha‐cypermethrin), followed by the PN population (24.4% deltamethrin, 35% permethrin, and 34.4% for alpha‐cypermethrin) by rapidly escaping test chambers after direct contact with surfaces treated with each active ingredient compared with match‐paired untreated controls. Moderate non‐contact repellency responses to all three compounds were observed in the TR population but were comparatively weaker than paired contact tests. Few mosquitoes from the SK and ST populations escaped from test chambers, regardless of insecticide tested or type of trial. We conclude that contact excitation was a major behavioral response in two populations of An. epiroticus, whereas two other populations showed virtually no escape response following exposure to the three pyrethroids. The explanation for these large unexpected differences in avoidance responses between pyrethroid‐susceptible populations of the same species is unclear and warrants further investigation.     

Biological and chemical assays of pyrethroids in cattle dung

Bioassays were developed in Zimbabwe to measure pyrethroid in cattle dung. These and chemical assays then estimated concentrations in dung from treated oxen and elucidated risks to dung fauna. Laboratory bioassays with adult beetles (Histeridae and Scarabaeinae, including Copris, Digitonthophagus, Onitis and Sisyphus spp.) and muscoid larvae (Musca lusoria Wiedemann) indicated that the LC50 of pyrethroids, as ppm in the wet weight, averaged 0.04 for deltamethrin pour-on, 0.25 for deltamethrin dip, 0.22 for alphacypermthrin pour-on, 0.10 for cyfluthrin pour-on, 0.23 for cypermethrin dip and 0.63 for flumethrin dip. Field bioassays involved artificial dung pats of 800 g, deployed in woodland and inspected after 24 h to record insects dead and alive. Beetles were most abundant in the wet season. Muscoid larvae were less seasonal. The LC50 of insecticides in the field confirmed laboratory indications. Adult Diptera (muscoids and Sgifidae) were not repelled or killed until the deltamethrin concentration reached 10 ppm. Pat dispersal by dung fauna and termites (Microtermes spp.) was halved by deltamethrin at 0.1-1 ppm. Scavenging of dead beetles by ants was greatest with small beetles (< 15 mm long) uncontaminated with insecticide. Dips and pour-ons of deltamethrin on cattle gave residues of about 0.01-0.1 ppm in dung produced in the fortnight after application. About 1.6% of the deltamethrin applied was transferred to dung. Deltamethrin and alphacypermethrin in dung showed no detectable degradation in 64 days. Contamination levels threaten populations of slow-breeding beetles.     

Estimating carrying capacity in a newly colonized sand fly Lutzomyia serrana (Diptera: Psychodidae)

The phlebotomine sand fly Lutzomyia serrana (Damasceno & Arouck) was mass-reared tinder conditions of varying densities in an effort to improve colony production efficiency. To do this, the experimental carrying capacity of a standard rearing chamber was determined, i.e., the optimum population size in relation to density (individuals per unit of space). Rearing chambers of 100 cm3 were populated with 1-50 L. serrana engorged females and an equal number of males. Laboratory conditions were maintained at 23-26 degrees C and 85-95% RH. The following parameters were recorded for each experimental chamber (three replicates): (1) female mortality without oviposition, (2) number of eggs oviposited and (3) number of adults emerging from the egg cohort. Female mortality began to increase substantially in the 26-female chamber, from 5.7% to 15% and finally reaching 60.2% in the 46-50 female chambers. In the chambers containing 1-20 females, egg number and realized adult progeny increased linearly to reach an asymptote. In the 20-50 female chambers, the number of eggs ranged from 420 to 699, and adult production from 306 to 432. The optimum carrying capacity for the 100-cm3 chambers was 22 +/- 2 females. Beyond this number, auto-regulation was initiated, i.e., female mortality without oviposition increased as the number of females per chamber increased. Total number of eggs and adult production was similar in all chambers containing 20-50 females. In conclusion, for optimizing production of mass reared sand flies, determination of the carrying capacity is essential to optimize use of insectary resources, to avoid loss of valuable potentially ovipositing females, and to increase overall production efficiency.     

Host feeding responses of Aedes aegypti (L.) exposed to deltamethrin

Escape responses of mated and unmated nulliparous Aedes aegypti mosquitoes were compared using three different concentrations of deltamethrin in the presence or absence of a live animal host using an excito-repellency (ER) test system. Both insecticide contact (excitation) and non-contact (repellency) test configurations were compared. For contact trials, mated mosquitoes showed similar escape movements among the three concentrations when host stimuli were absent. Significant differences in responses were seen between the lower concentrations of (LC(50) and LC(75) ) deltamethrin with and without hosts present (P<0.05). Presence or absence of host stimuli produced no significant differences in escape response for unmated females when exposed to the highest concentration (LC(90) ) of deltamethrin. Our findings indicate that as deltamethrin concentrations decrease to sublethal levels, mating status and host cues play a more significant role in escape behavior. Therefore, insemination can influence the outcome of feeding success and flight movement of nulliparous female Ae. aegypti in contact with deltamethrin and in the presence of live host stimuli. The ER assay system serves as a useful tool for observing excitation and repellency responses of Ae. aegypti to insecticides in the presence or absence of other environmental and biological cues that can affect mosquito behavior.     

Spraying pyrethroid and neonicotinoid insecticides can induce outbreaks of <Emphasis Type="Italic">Panonychus citri</Emphasis> (Trombidiformes: Tetranychidae) in citrus groves

Panonychus citri (McGregor) (Trombidiformes: Tetranychidae) is one of the main defoliator mites in citrus groves. In Brazil, P. citri was formerly considered a secondary pest, but in recent years, the population levels of this mite have increased in many groves, requiring additional acaricide applications for its control. The population growth of P. citri is associated with the increase in the number of applications of pyrethroid and neonicotinoid insecticides to control insect citrus pests. This study assessed the effects of pyrethroid (deltamethrin, esfenvalerate, λ-cyhalothrin) and neonicotinoid (imidacloprid and thiamethoxam) insecticides on biological, behavioral and demographic parameters of P. citri. None of the insecticides tested affected larval hatching, but deltamethrin, esfenvalerate, and λ-cyhalothrin reduced the survival of larvae and protonymphs. Deltamethrin, esfenvalerate, and λ-cyhalothrin induced a significant increase in the fecundity of surviving females. Pyrethroids also caused repellency and changed feeding and oviposition preferences. In contrast, imidacloprid and thiamethoxam did not affect the survival of immature stages, but imidacloprid significantly increased fecundity. Imidacloprid and thiamethoxam did not cause any repellent effect or changes in the feeding and oviposition preferences. Based on the demographic parameters, deltamethrin, λ-cyhalothrin, and imidacloprid increased R_o, r, and λ, whereas esfenvalerate and thiamethoxam were similar to the control. Therefore, the use of these insecticides (especially deltamethrin, λ-cyhalothrin, and imidacloprid) requires caution, such as avoiding repeated use of these compounds during the periods of P. citri incidence in citrus groves.     

Laboratory Evaluation of a Laboratory-selected Organophosphate-resistant Strain of Amblyseius finlandicus (Acari: Phytoseiidae) for Possible Use in Finnish Apple Orchards

The survival of adults and immatures, and reproduction at rates of 150, 300 and 900 ppm a.i. of azinphosmethyl were compared among four types of Amblyseius finlandicus females and their offspring; a laboratory-selected colony (SEL16) resistant to azinphosmethyl, an unselected base colony (Tuorla), reciprocal F1 females from crosses between SEL16 and a very susceptible colony (Hiekkaharju). The SEL16 and reciprocal F1 females had a higher survivorship than the unselected Tuorla base colony after 2 and 4 days on leaves treated with the three concentrations of insecticide. Azinphosmethyl decreased oviposition by the surviving females of all types, but the decrease was smaller in the SEL16 strain than in the base colony. The survivorship of immatures of SEL16 on fresh azinphosmethyl residues after 6 days was low at all three concentrations, but no survivors were found in the base colony at any of the concentrations. Females deposited significantly more eggs on the untreated areas of the leaves. The importance of this behavior for biological control is discussed. There were no significant differences in developmental rate, ovipositional rate, sex ratio and ovipositional period between the SEL16 and unselected base colony on untreated leaf substrates, suggesting that resistance was not associated with decreased fitness. A mode of inheritance study indicated that azinphosmethyl resistance was incompletely dominant. This was also suggested by the results of bioassays, where the reciprocal F1 females performed nearly as well as the SEL16 strain on leaves treated with field rates of azinphosmethyl.     

Orchard selection for resistance to a synthetic pyrethroid in organophosphate—resistant Typhlodromus pyri in the UK

Organophosphate resistant Typhlodromus pyri were exposed to deltamethrin in replicated orchard plots from 1986–90. Treatments of 6.3, 3.1, 1.7 and 0.8 g active ingredient (ai) ha^?1 deltamethrin were applied 14 times over the 5‐year period; a 12.5 g ai ha^?1 treatment was discontinued in 1989 after eight applications. Few phytoseiids were found in the plots receiving the two highest rates of deltamethrin. Bioassays at the end of the five‐year period showed a progressive increase in LC₅₀ from the untreated strain (0.40 ppm ai) to the strain that had been exposed to 3.1 g ai ha^{‐1 1} (1.50 ppm ai) indicating a four‐fold increase in resistance in these selected mites.     

用溴氰菊酯选育抗敌百虫淡色库蚊的研究

将室内选育成功的抗敌百虫淡色库蚊Culex pipiens pallens Coq.品系(RD)分为二个分系,一个不再用敌百虫处理,称之为RD衰退品系(RD_139-x),34代后对敌百虫的敏感度增加了10倍,对溴氰菊酯的敏感度无显著变化.另一分系改用溴氰菊酯选育,命名为Rde品系,53代后对溴氰菊酯抗性达200倍左右,对敌百虫敏感度上升约10倍,对DDT的交互抗性高达118倍,对马拉硫磷、杀螟硫磷的敏感度与敏感品系(SEN,上海昆虫所保存)比较也有上升,呈负交互抗性现象.用高剂量溴氰菊酯处理幼虫、也证明Rde在20分钟内麻痹率比敏感品系低,可见抗性机制主要是抗击倒因子(Kdr).但增效醚(Pb)对溴氰菊酯明显增效,可见mfo酶也起重要作用,推测抗性为多因子遗传.     

Choice of oviposition site between surface of the medium and paper in four Indian species of Drosophila

Choice of oviposition site between surface of the medium and paper positioned vertically on the medium by females was studied in four species of Drosophila: D. ananassae, D. bipectinata, D. malerkotliana, and D. biarmipes. Several geographic strains of these species were used. Females of all the four species laid greater proportions of eggs on the surface of medium as compared to surface of the paper. Thus all the four species tested show preference for oviposition on surface of medium. When the comparison is made for oviposition on paper among the four species, D. ananassae lays more eggs on the surface of paper as compared to other three species.     

Effects of prostaglandin F2 alpha prostaglandin E2 and arachidonic acid on the induction of oviposition in vivo and in vitro in oviparous lizards.

Gravid females of four different species of oviparous lizard were treated in vivo with varying doses of prostaglandin F2 alpha (PGF2 alpha), prostaglandin E2 or arachidonic acid (AA). In contrast to previous studies examining birds and viviparous lizards, no dosage induced oviposition in any of the treated females. All females, however, did exhibit behaviors associated with oviposition. Intact oviducts removed from gravid females and placed in organ culture did oviposit when treated with 30 or 100 ng PGF2 alpha/ml of culture media. Arachidonic acid at similar concentrations also was effective in stimulating birth. These data suggest that prostaglandins can stimulate oviposition in oviparous lizards but further suggest that their action may be inhibited by oviducal innervation until just prior to natural birth.     

Loss of Nesting Behavior and the Evolution of Viviparity in Reptiles

Presence or absence of nesting behavior during spontaneous or hormone-induced oviposition was determined in captive, oviparous lizards (Anolis carolinensis and Sceloporus undulatus). The occurrence of nesting behavior [digging of a nest cavity, covering the egg(s) with substrate] was determined directly by observation of ovipositing females as well as indirectly by whether eggs were covered (buried). Under uncrowded conditions in large terraria, most females of both species nested. However, under crowded conditions (S. undulatus), or in small cages (A. carolinensis), females oviposited without displaying species-typical nesting behavior. Facultative suppression of nesting behavior during oviposition can occur in nature as well, and this inhibition of behavior may be adaptive. We hypothesize that the absence of nesting behavior in viviparous lizards may be controlled by physiological mechanisms similar to those that control facultative suppression in closely related oviparous species.