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1.
The brown planthopper, Nilaparvata lugens (Stål) (Hemiptera: Delphacidae), is an insect pest in which offspring are produced by the mating of adult males with adult females. This species is a classic case in which pest resurgence is induced by insecticides. In the past, studies of resurgence mechanisms have focused on insecticide-induced stimulation of reproduction in adult females. To date, however, the role that males play in the resurgence mechanisms of N. lugens has not been investigated. The aim of the present study is to examine changes in protein levels in male accessory glands (MAGs) induced by the insecticides triazophos and deltamethrin and to determine their relationship with vitellin content in the fat bodies and ovaries of adult females in the context of mating pairs. Our results show that protein content in MAGs is significantly affected by male mating status, insecticide type, and insecticide concentration. Insecticide application induced increased protein levels in MAGs. A greater quantity of MAG products was transferred to females via mating. Thus, protein levels in MAGs significantly decreased after mating. Experimental matings indicate that vitellin content in both fat bodies and ovaries of adult females in mating pairs consisting of a treated male and an untreated female (♂t × ♀ck) is significantly greater than that of females in pairs consisting of an untreated male and an untreated female (♂ck × ♀ck). Under various concentrations of the two insecticides, vitellin levels are highest in mating pairs consisting of a treated male and a treated female (♂t × ♀t), followed by mating pairs consisting of an untreated male with a treated female (♂ck × ♀t). These findings demonstrate that (1) insecticides have an effect on males; (2) insecticide effect can be transferred to females; and (3) the reproductive effect of insecticides is strongest in mating pairs in which both the males and females are treated compared to pairs in which only one individual is treated. These findings provide valuable information about the role of males in pesticide-induced resurgence of N. lugens.  相似文献   

2.
Cucurbitacins are plant defensive chemicals that attract many species of adapted insect herbivores such as luperine leaf beetles, and they have been employed in traps and toxic baits. Male and female beetles feed avidly on baits containing these compounds, but field trials have revealed that males find them far more attractive than females. A wind-oriented baited sticky trap was designed to evaluate the response of Diabrotica speciosa to cucurbit extracts, by means of a mark–release–recapture experiment. The spatial range of attraction was less than 20 m, and captures were almost exclusively of males (99.91%). Distance attraction for D. speciosa to a point-source of bitter cucurbit juices is probably exclusive to males. These conclusions probably apply to most Diabrotica species, of which many are crop pests.  相似文献   

3.
Acetylocholine, arecoline, 2-(dimethylamino)ethyl acetate, L-glutamic acid, L-4-methyl-eneglutamic acid, (±)-quisqualic acid, 4-aminobutyric acid, and dicrotophos were injected into the haemocoel of adult male Lucilia sericata. Large doses of the putative transmitters and their analogues were required for toxicity. The water soluble organo-phosphate dicrotophos was much more toxic than any of the other compounds. Electrophysiological experiments indicated that the putative transmitters were reaching their presumed site of action in the nervous system and that their toxicity could be correlated with the intensity and duration of their effect at this site. Biochemical measurements of the rate of loss of the putative transmitters from the haemolymph indicate that, in vivo, the test insect possesses efficient mechanisms for removing these compounds from the system being studied. It is concluded that the low toxicity of the putative transmitters, which are presumed to interact reversibly with post synaptic receptor sites, may be largely due to their rapid removal from the system, resulting in a rapid fall in concentration at the receptor site.  相似文献   

4.
The present study reports on the insecticidal and acaricidal potentials of dibenzyltrisulfide (DBTS) isolated from the roots of Petiveria alliacea L. using thin layer and high performance liquid chromatography. The 96-h LD50 value (μg per tick) obtained for adult Boophilus microplus (Canestrini) topically treated with DBTS was 0·920. The LD50 values obtained for three commercial acaricides dimethoate, lindane and carbaryl were 4·6, 9·3 and 6·9 μg per tick respectively. The IOD50 and IHD50 (concentrations inhibiting egg laying and hatching by 50% respectively) in μg per tick doses for DBTS were 0·22 and 0·24 respectively. The 24-h LD50 dose (μg per insect) obtained for DBTS on adult Cylas formicarius elegantulus (Summer) was 0·193 μg per insect. The vapour from a stock solution of 5 g litre-1 of DBTS was highly toxic to adult Hypothenemus hampei Ferr. inside coffee berries, inflicting 89% mortality within 24 h. © 1997 SCI.  相似文献   

5.
To investigate relationships between the molecular structure of pyrethroids and their mode of action, toxicities to adult male Periplaneta americana by topical application and injection were compared with toxicities to their giant fibre nerve axons. From the tests against intact insects it was concluded that: (i) although ED50S ranged from 0.04 to 65 μg/insect, each compound was equally toxic, with one exception, when administered by either route; (ii) esters of (1 R)-cis- were more toxic than esters of the corresponding (1 R)-trans-3-substituted-2, 2-dimethylcyclopropanecarboxylic acids; (iii) α-cyano-3-phenoxybenzyl esters were more toxic than the corresponding 3-phenoxybenzyl esters; (iv) changes in the alcoholic component of some compounds (particularly trans-isomers of esters of 5-benzyl-3-furylmethanol and esters of α-cyano-3-phenoxybenzyl alcohol) affected a recovery phase in their ED50/time curves more than changes in the acid component; (v) the amount of recovery was positively correlated with molecular polarity. The concentration required to decrease the amplitude of the action potential of giant fibres by 30% in 1 h ranged from 0.26 μM for the most active compound to 100 μM for the least active. There was no clear relationship between neurotoxicity and toxicity to whole insects and little association between neurotoxicity and features of molecular structure. Neurotoxicity was, however, positively correlated with polarity. Giant fibre axons seem unlikely to be critical sites of action of pyrethroids.  相似文献   

6.
The residues from metered doses of cypermethrin were recovered from excised portions of grasshopper cuticle to determine losses by volatilisation. Residues from similar doses were also recovered from the cuticles of intact grasshoppers and from whole body homogenates after rinsing the cuticle, to determine rates of absorption and losses from metabolism. Residues were recovered from males and females one week and three weeks after fledging in grasshoppers infected with Malameba locustae and in uninfected ones. They were maintained at 15 or 30°C and sampled from each combination of factors at 4, 8, 16, 24, 30 and 48 h after treatment. There was no measurable loss of cypermethrin by volatilisation up to 72 h after application to excised portions of cuticle at either 15 or 30°C. In all combinations of factors, more cypermethrin was recovered externally (P <0.05) from grasshoppers held at 15°C than those held at 30°C and more from infected grasshoppers than from those that were uninfected. Significantly more cypermethrin was also recovered externally from males than from females (P <0.05) and more from infected one-week-old grasshoppers than those that were three weeks old. At 15°C there was a gradual trend towards accumulation of cypermethrin internally, but at 30°C an initial trend towards accumulation was followed by one of decline. Residual cypermethrin recovered could in general be related to the negative temperature coefficient of toxicity, to a decreased sensitivity to cypermethrin in infected grasshoppers and to an increased sensitivity in older grasshoppers.  相似文献   

7.
以构效关系为线索,根据类同合成法和活性官能团拼接策略,以阿维菌素为先导分子,在其4"-位引入硫脲或脲活性结构单元,合成了一系列酰基硫脲（9a~9o）和芳基脲（10a~10i）阿维菌素衍生物,所有目标化合物均经1H NMR、MS和元素分析确证。室内杀虫活性测定结果表明:所有衍生物对朱砂叶螨Tetranychus cinnabarinus和甘蓝蚜Brevicoryne brassicae均表现出不同程度的毒杀活性,大部分化合物对甘蓝蚜的杀虫活性优于阿维菌素B1a,其中化合物9h对朱砂叶螨和甘蓝蚜的LC50值分别为0.100和1.71 μmol/L,表现出很高的毒杀活性,化合物9o对甘蓝蚜的毒性最高,LC50值为1.13 μmol/L。  相似文献   

8.
The mechanisms adopted to ensure mating success, fertility and fecundity ofS. littoralis were studied. The male moths usually mate only once a night but they mate repeatedly during most of their life span, and practically all their spermatophores are equally efficient for inseminating a female. Although females are also multiple maters, one spermatophore is sufficient for a female to lay fertile eggs throughout her life with no reduction in potential fecundity. While a male may mate 5.3 times, on the average, a female may mate only 2.3 times. As a pronounced decrease in pheromone release occurs after mating, a repeat mating by a female will occur only after most neighboring competitive virgin females have been inseminated. A male may mate therefore with 5.3 different females, all of which will be thoroughly inseminated. The female moth is ready to mate just after emergence and at any time throughout her life. If mating is delayed the preoviposition period is greatly prolonged and eggs are saved to be laid later, after mating, as fertile eggs. Delay in egg laying due to delayed insemination does not result in reduced fecundity as it is compensated for by prolonged longevity. Even if mating is greatly delayed and occurs after egg laying has already begun, the potential reduction in reproduction is not very great, due to the low daily egg-laying rate and the increased longevity of unmated females. It appears unreasonable to expect any tendency toward reduction of egg production with a decrease in the ratio of adult males in a population; for this purpose the control of males must be essentially complete. Therefore, a behavioral control program by mass trapping ofS. littoralis males is unlikely to be economically feasible.  相似文献   

9.
Several 2-carboxylbenzofurans and their coumarin precursors, compounds 1 – 6 , and the novel compound 7 were synthesized and their insecticidal activity studied using adult sweet potato weevils (Cylas formicarius elegantulus (Summer)) at 24 μg, 48 μg and 72 μg per insect in 0.5 ml litre?1 piperonyl butoxide (PPB) in acetone. The order of toxicity of the compounds as judged by the percentage mortality at 24 μg per insect at 48 h was 2 (100%) > 6 (95%) > 7 (85%) > 4 (75%)) > 3 (65%) > 1 (60%) > 5 (45%) > piperonyl butoxide (0.0%). Compound 2 was equitoxic to 24 μg of technical grade dimethoate. When administered in acetone alone, however, the compounds were only moderately active (i.e. > 120 μg per insect was required for 60% mortality at 48 h). The test compounds were more active at lower doses (48–72 μg per insect) when dissolved in dimethylsulfoxide or in an oil extract obtained from the fruit of Blighia sapida Koenig.  相似文献   

10.
Eight non-peptidic chemical analogs of trypsin modulating oostatic factor (TMOF, NH2-YDPAP6), an insect hormone inhibiting trypsin biosynthesis in mosquitoes, were synthesized based on the structure of the native peptide. The median lethal concentration (LC50) for the chemical analogs, TMOF and FDPAP (a peptidic analog of TMOF) was estimated for larvae of the northern house mosquito, the Culex pipiens complex, using a static 5-day bioassay. Four of these compounds demonstrated the same larvicidal activity as TMOF, while three of these compounds were 1.2-2.5-fold more active than TMOF. The compounds introduced by injection were toxic to fourth instars of the tobacco hornworm, Manduca sexta, except for TMOF, FDPAP, and PPHEN. Injection of TMOF and FDPAP into fourth stadium and TMOF into second stadium M. sexta had no effect on trypsin activity, growth, or mortality. Apparently the mosquito hormone is inactive in the tobacco hornworm at the developmental stages examined. Three TMOF analogs (CHEA, PHEA, and PHA) demonstrating the highest activity by injection in M. sexta were also found to be toxic by injection in fourth instars of the tobacco budworm, Heliothis virescens, and the cotton bollworm, Helicoverpa zea, as well as adult male German cockroaches, Blattela germanica. A two-choice feeding bioassay with H. virescens indicated that at least one of the TMOF analogs, PHEA, has anti-feeding properties.  相似文献   

11.
The toxicity of ryanodine ( 1 ) and 9,21-didehydroryanodine ( 2 ) (the principal active ingredients of the botanical insecticide ryania) to adult female house flies (Musca domestica L.) is attributable to binding to the ryanodine receptor (ryr) and thereby disrupting the Ca2+-release channel. These ryanoids, assayed in house flies with piperonyl butoxide (PBO) to suppress cytochrome P450-dependent detoxification, give injected KD50 values of 0·07–0·11 μg g-1, injected LD50 values of 0·39–0·45 μg g-1 and topical LD50 values of 12– 50 μg g-1. They inhibit the [3H]ryanodine binding site of house fly and rabbit muscle with IC50 values of 3–10 nM . This study examines the effect of structure on potency, with 15 variants of the cyclohexane substituents, two 4,6-cyclic boron and two methylated derivatives, and four modifications of the isopropyl and ester substituents. The most effective compound examined was 10-deoxy- 2 ( 3 ) which was more potent than 2 by 2–4-fold on injection and 29-fold applied topically following PBO (LD50 0·41 μg g-1). Additional high-potency compounds were 10-oxo- 1 and the cyclohexane variants with lactam, 21-nor-9-oxo and 21-nor-10-deoxy substituents. Other modifications usually reduced toxicity. The injected knockdown potency of the ester ryanoids was generally related to their effectiveness in competing with [3H]ryanodine at the ryr of rabbit skeletal muscle. Two non-ester ryanoids, ryanodol and 9,21-didehydroryanodol, were found to be more toxic than predicted from their potency at the ryr and may therefore act in a different manner such as at a K+ channel, as suggested by Usherwood and Vais. Clearly ryanoids are challenging prototypes for a potential new generation of insecticides. © 1997 SCI.  相似文献   

12.
Cucurbitacin-rich extracts are phagostimulants for both male and female Luperini, but field trials reveal that males are far more attracted to them than females. The sex ratio and number of beetles killed by an application of cucurbitacin-based toxic baits was assessed at two different scales: small areas of 100 m2, and a larger area of 10,000 m2. The small area bait applications killed mostly males (95.2%), but the 1-ha treated plot showed a lower sexual bias (57% male). An earlier study indicated point sources (sticky traps) attracted only males. Results indicate that the distance attraction to bitter cucurbit extracts is almost exclusive to males, but the wide dispersal of a toxic bait based on them should promote encounter and control of both sexes within the treated area. No significant non-target effects were observed.  相似文献   

13.

BACKGROUND

The sterile insect technique (SIT) is a green and species-specific insect pest control technique that suppresses target populations by releasing factory-reared, radiosterilized males into the wild. Once released, it is important to be able to distinguish the released males from the wild males for monitoring purposes. Several methods to mark the sterile males exist. However, most have limitations due to monetary, process efficiency, or insect quality. Aedes albopictus is naturally infected with Wolbachia at a high prevalence, therefore the elimination of Wolbachia can serve as a biomarker to distinguish factory-reared male mosquitoes from wild conspecifics.

RESULTS

In this study, a Wolbachia-free Ae. albopictus GT strain was developed and its fitness evaluated, which was found to be comparable to the wild GUA strain. In addition, GT male mosquitoes were irradiated at the adult stage and a dose of 20 Gy or more induced over 99% sterility. Moreover, a dose of 30 Gy (almost completely sterilizing male and female mosquitoes) had limited effects on the mating competitiveness of GT males and the vector competence of GT females, respectively. However, radiation reduced mosquito longevity, regardless of sex.

CONCLUSION

Our results indicate that the Ae. albopictus GT strain can be distinguished from wild mosquitoes based on Wolbachia status and shows similar fitness, radio-sensitivity and arbovirus susceptibility to the GUA strain, indicating that it is feasible to use the GT strain to suppress Ae. albopictus populations for SIT programmes. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.  相似文献   

14.
The in vivo release of 14CO2 arising from decarbamoylation of l-naphthyl methyl [14C]carbamate (carbaryl) injected into male and female Periplaneta americana was measured over the range from 0.2 to 50 nmol carbaryl/g body weight. The amount of 14CO2 released was proportional to the dose of [14C]-carbaryl injected and was not significantly different between male and female cockroaches. Carbaryl was found to be more toxic to male (KD100, 12 nmol carbaryl/g) than female (KD100′ 57 nmol carbaryl/g) cockroaches, at any dose which caused knockdown, females showed a greater ability to recover from the toxic syndrome than did males. The [14C]-carbaryl metabolism (decarbamoylation) was temperature dependent and could be partially inhibited by sesamex, tri-orthocresyl phosphate and anoxia. Secondary effects of carbaryl poisoning were severe dehydration of the animals and in some cases abdominal swelling due to air being gulped into the crop. The amount of dehydration was essentially unaltered by the chemical inhibitors, but was partially reduced by anoxia and cooling. In the most severe cases of dehydration animals lost 18 % of their body water content.  相似文献   

15.
人工招引粉红椋鸟控制蝗害是一种生物防蝗的重要手段,鸟巢结构以及粉红椋鸟迁离时间均影响其对蝗虫的防治效果。本文通过调查新疆地区不同结构的鸟巢中粉红椋鸟数量及其对鸟巢利用率,并结合粉红椋鸟迁离时间分析其对蝗虫的防控能力。结果表明,在调查的16个蝗虫发生区内,不同结构鸟巢招引效果为砖巢 > 石巢 > 天然鸟巢,砖巢、石巢和天然鸟巢招引效果分别为74.8%、71.9%和66.5%。分析粉红椋鸟迁离时间对蝗虫种群密度影响,成鸟迁离前对蝗虫的防控效果平均达58.4%,幼鸟迁离前对蝗虫的防控效果为88.8%。本文为进一步利用粉红椋鸟防治草原蝗虫提供重要理论依据。  相似文献   

16.
Seed-feeding by larvae of the mosquito head fly, Melanagromyza minimoides, can substantially reduce yields of late-planted sunflower in South America and its management with insecticides or early-planting has other undesirable costs. Evaluation of inbred lines over three seasons indicated differences in the emergence of adult flies, particularly between restorer (male) and maintainer (female) lines used for hybrid seed production; when fly emergence (≈damage) was adjusted for differences in head size (i.e. to flies/100 cm2), restorer lines averaged 3–12 times more damage than maintainer lines. Fly emergence in each of two seasons was tested for correlations with three sunflower traits (glandular trichome number, pericarp strength, and sesquiterpene lactone content) believed to provide host plant resistance to other insects. In one of two years, fly emergence was negatively correlated with the relative amount of sesquiterpene lactones in florets of the tested lines. Also, among maintainer lines, severity of infestation was much greater in multi-headed inbreds compared to single-headed lines. Additional research is needed to establish the cause(s) of reduced susceptibility of inbreds and whether parental lines influence M. minimoides damage to hybrids.  相似文献   

17.
BACKGROUND: This study focused on determining the minimal effective gamma radiation dose that prevents commodity damage caused by the Indian meal moth Plodia interpunctella (Hübner). The study was also designed to assess the effect of releasing either partially sterilized males alone or both partially sterilized males and females on the reproductive potential of P. interpunctella populations. RESULTS: The dose of radiation required to prevent larval emergence from irradiated eggs was 350 Gy, and the same dose was also required to prevent adult emergence from mature larvae. A dose of 300 Gy was not able to prevent adult emergence from irradiated pupae. The dose at which 100% sterility was achieved in treated females mated to treated males was 300 Gy for the parental generation of irradiated pupae. Fertility of the parental males from irradiated pupae was 48.17% at 300 Gy in treated males crossed with untreated females, but male progeny of irradiated male parents had a residual fertility of 11.06% at the same dose. CONCLUSION: F(1) males from irradiated pupae were more sterile than parental males. To prevent larval emergence from irradiated eggs, a dose of 350 Gy is required. The same dose is required to prevent the larvae from reaching the adult stage.  相似文献   

18.
Inoculation     
Terpenes and biogenically related phenols commonly found in plant essential oils are known to be toxic to insect pests. Accordingly thymol was tested for acute toxicity via topical application to diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae) and its parasitoid, Cotesia plutellae (Kurdjunov) (Hymenoptera: Braconidae under laboratory conditions. Topical application to adult female parasitoids versus second instars of P. xylostella showed that thymol was about 62 times less toxic to the parasitoid than to the host larvae with 24 h LD50 of 0.052 and 0.0008M, respectively. Although thymol was less toxic to the parasitoid, some biological parameters of the progeny at sublethal doses of surviving parasitoids were impaired such as rate of emergence and development time of larvae and pupae. The impact on detoxification enzymes was also studied and there was no significant induction in cytochrome P450 and carboxylesterase activities in both treated male and female wasps. Results obtained suggest that parasitoid is able to withstand the impact of thymol significantly.  相似文献   

19.
‘Candidatus Liberibacter solanacearum (Lso)’ is a pathogen of Solanaceae but also causes serious physiological disorders in carrots and celery (Apiaceae). In carrots, this pathogen is transmitted by the psyllids Bactericera trigonica and Trioza apicalis. How vector sex influences Lso transmission has not been yet elucidated. Here we report the probing behaviours of male and female B. trigonica and their impact on Lso titre transmitted, percentage of transmission, and symptoms produced on carrots when Lso is transmitted by males or females of B. trigonica. Vector sex affected the inoculation of Lso; our results suggest that females might inoculate higher Lso titres than males. However, the percentage of transmission was not affected by vector sex at a density of one or eight psyllids per plant. The number of yellow leaves and root weight were not different when Lso was transmitted by males or females at either of the psyllid densities tested, except for groups of females whose Lso transmission resulted in a higher number of yellow leaves than did Lso transmitted by groups of males. Electrical penetration graphs (EPG) showed that the proportion of individuals who reached phloem tissues was similar for males and females. However, EPGs also showed that females probed more times, ingested longer from phloem sieve elements and reached phloem tissues more frequently than did males during an 8-h inoculation access period (IAP). Our study shows that differences in probing behaviours between males and females of B. trigonica could modulate how Lso is inoculated by psyllids. These results highlight the importance of taking sex into consideration in psyllid studies of probing behaviour and bacterial transmission.  相似文献   

20.
BACKGROUND: Upon emergence from their pupal cells, bollworm, Helicoverpa zea (Boddie), adults actively seek and feed on plant exudates before they disperse and reproduce on suitable host plants. This nocturnal behavior of the bollworm may be exploited as a pest management strategy for suppression of the insect by using an attractant/stimulant mixed with an insecticide to induce feeding to cause adult mortality or reproductive reduction/inhibition. This study aimed to determine in the laboratory whether or not spinosad when mixed with sucrose solution as a feeding stimulant and ingested by bollworm could influence mortality and reproduction of the insect. RESULTS: Sublethal concentrations of spinosad fed to laboratory‐reared females confined with males significantly reduced percentage hatch of eggs at 0.1 mg L?1, and it was reduced to near zero at 2.5 mg L?1 when compared with females fed 2.5 M sucrose solutions only. The lethal concentration (LC99) for males captured from the field in sex‐pheromone‐baited traps was 73 mg L?1 for 24 h response. Proboscis extension response was not inhibited significantly even at 10 g L?1. In spite of a 137‐fold increase in lethal dose concentration, spinosad did not inhibit feeding. CONCLUSION: A detailed study of laboratory‐reared and field‐collected bollworm adults relative to mortality and reproduction after ingestion of spinosad indicates that spinosad would be useful in an attract‐and‐kill strategy to control the insect when mixed with a feeding attractant/stimulant. Field validation of the data is warranted. Published 2010 by John Wiley & Sons, Ltd.  相似文献   

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