Oviposition Deterrent Research Articles

Insecticidal and Feeding Deterrent Effects of Kaempferia galanga L. and Amomum subulatum on Pieris rapae L. Larva.

<b>Background and Objective:</b> <i>Pieris rapae</i> L., is one of the most widespread and destructive pests of cruciferous plants. At present, synthetic chemical insecticide is still the main approach to control this pest despite several disadvantages to human health and the wildlife environment as well as biological resistance. To search for plants having insecticidal activity, the biological effects of two medicinal plants <i>Kaempferia galanga</i> L. and <i>Amomum subulatum </i>on <i>Pieris rapae</i> L., were investigated. <b>Materials and Methods:</b> The methanol extracts of dry rhizomes and fruits of <i>Kaempferia galanga</i> L. and <i>Amomum subulatum </i>were used to determine the mortality, feeding and oviposition deterrence of larvae and adult of <i>Pieris rapae</i> L. <b>Results:</b> <i>Kaempferia galanga</i> L. and <i>Amomum subulatum</i> exhibited insecticidal activity against <i>Pieris rapae</i> L., with LC<sub>50</sub> values of 2.11 and 11.80% (w/v), respectively. In the antifeedant test, <i>Kaempferia galanga</i> L., extract showed no significant difference with the control at the low concentration (0.5 and 1%). Whereas, with a concentration of 0.5%, <i>Amomum subulatum</i> extract demonstrated a high antifeedant effect on <i>Pieris rapae</i> L., larvae. In addition, plants treated with these two extracts reduced eggs laid by <i>Pieris rapae</i> L., in field conditions showing the oviposition deterrent properties. <b>Conclusion:</b> These results indicated that <i>Kaempferia galanga</i> L. and <i>Amomum subulatum </i>extracts have insecticidal substances against <i>Pieris rapae </i>L., which can be used for developing effective pesticides or/and oviposition deterrents for integrated pest management.

Antifeeding and Oviposition Deterrent Effect of Ludwigia spp. (Onagraceae) against Plutella xylostella (Lepidoptera: Plutellidae).

Plants produce a wide variety of bioactive compounds with insecticidal properties, such as secondary metabolites capable of interfering with the nutrition and reproduction of pest species such as Plutella xylostella. Thus, the objective of this study was to evaluate the effects of aqueous and ethanolic extracts of Ludwigia spp. (Onagraceae) on the feeding and oviposition of P. xylostella. Choice bioassays were performed using aqueous and ethanolic extracts. The aqueous extract of L. tomentosa resulted in an approximately 81% reduction in larval feeding compared to that in the control, with an antifeedant index (AI) of 52%. The aqueous and ethanolic extract of L. nervosa acted by stimulating larval feeding. The oviposition was significantly reduced in the kale leaves treated with aqueous and ethanolic extracts of Ludwigia spp. The aqueous extracts promoted an average 90% reduction in oviposition when compared to that in the control, and an oviposition deterrent index (ODI) above 61% was classified as an oviposition deterrent. In addition, ethanolic extracts affected 81% of oviposition, with an ODI above 41%. Bioassays should be performed to clarify the use of aqueous and ethanolic extracts of L. nervosa as they acted as phagostimulants in the feeding tests and as deterrents in the oviposition tests. The phenolic compounds—flavonoids, condensed tannins, and alkaloids—were more abundant in L. nervosa, L. tomentosa, L. sericea, and L. longifolia. The extracts of L. longifolia and L. tomentosa showed the best results, interfering with the host choice for feeding and oviposition in P. xylostella and representing an alternative for the control of diamondback moths.

Plant volatile compound methyl benzoate is highly effective against Spodoptera frugiperda and safe to non-target organisms as an eco-friendly botanical-insecticide

Recent studies have indicated that the plant volatile methyl benzoate (MB) exhibits significant insecticidal bioactivity against several common insects. However, the potential environmental hazards of MB and its safety to non-target organisms is poorly understood. In the present study, these characteristics were investigated through laboratory experiments and field investigations. The results revealed that MB was highly toxic to the agricultural pest, fall armyworm Spodoptera frugiperda. Compared with the commercial pesticide lambda-cyhalothrin, the toxicities of MB against S. frugiperda larvae and adults were comparable and 3.41 times higher, respectively. Behavioral bioassays showed that the percentage repellency of MB to S. frugiperda larvae was 56.72 %, and MB induced 69.40 % oviposition deterrence rate in S. frugiperda female adults. Furthermore, in terms of median lethal concentration (LC50) and median lethal doses (LD50), MB exhibited non-toxic effects on non-target animals with 3-d LC50 of > 1 % to natural predators (Coccinella septempunctata and Harmonia axyridis), 3-d LD50 of 467.86 µg/bee to the bumblebee Bombus terrestris, 14-d LC50 of 971.09 mg/kg to the earthworm Eisenia fetida, and 4-d LC50 of 47.30 mg/L to the zebrafish Brachydanio rerio. The accumulation of MB in the soil and earthworms was found to be extremely limited. Our comparative study clearly demonstrated that MB is effective as a selective botanical pesticide against S. frugiperda and it is safe to use in the tested environment, with no toxic effects on non-target animals and natural predators.

1-Octanol emitted by Oecophylla smaragdina weaver ants repels and deters oviposition in Queensland fruit fly

Humans have used weaver ants, Oecophylla smaragdina, as biological control agents to control insect pests in orchards for many centuries. Over recent decades, the effectiveness of weaver ants as biological control agents has been attributed in part to deterrent and oviposition inhibiting effects of kairomones produced by the ants, but the chemical identity of these kairomones has remained unknown. We have identified the kairomone responsible for deterrence and oviposition inhibition by O. smaragdina, providing a significant advance in understanding the chemical basis of their predator/prey interactions. Olfactometer assays with extracts from weaver ants demonstrated headspace volatiles to be highly repellent to Queensland fruit fly, Bactrocera tryoni. Using electrophysiology and bioassays, we demonstrate that this repellence is induced by a single compound, 1-octanol. Of 16 compounds identified in O. smaragdina headspace, only 1-octanol evoked an electrophysiological response from B. tryoni antennae. Flies had greatly reduced oviposition and spent significantly less time in an olfactometer arm in the presence of 1-octanol or a synthetic blend of headspace volatiles containing 1-octanol than in the presence of a synthetic blend of headspace volatiles without 1-octanol, or clean air. Taken together, our results demonstrate that 1-octanol is the functional kairomone component of O. smaragdina headspace that explains repellence and oviposition deterrence, and is hence an important contributor to the effectiveness of these ants as biological control agents.

Bioactivity of extracts from Syzygium aromaticum, Annona muricata, and Piper retrofractum against Spodoptera frugiperda J. E. Smith (Lepidoptera: Noctuidae)

Fall armyworm (FAW) Spodoptera frugiperda is an important pest on maize. One of the environmentally friendly control strategies of FAW is by utilizing botanical insecticides. Extracts of Syzygium aromaticum, Annona muricata, and Piper retrofractum are known to be able to control various types of insect pests and ensure sustainability in farming. The objective of this research was to study the effective control of three plant extracts against FAW, including the toxicity against larvae using leaf residual method, the feeding inhibition against larvae, and the oviposition deterrence against female. Probit analysis was used to estimate LC50 and LC95 values of the extracts. The extract of P. retrofractrum exhibited highest mortality compared to the other extracts with LC95 values of 0.230%, followed by S. aromaticum 0.349%, then A. muricata 1.387% against first-instar larvae at 96 hours. P. retrofractum extract showed the highest feeding inhibition of 90.14% at LC95 value, which gradually decreased on S. aromaticum and A. muricata extracts were 80.33% and 78.44%, respectively. Three plant extracts at LC99 and 2 x LC99 levels deterred female oviposition by 100%. This results indicate that P. retrofractum extract has great potential for further development as a botanical insecticide to controlling FAW.

Bio-insecticidal and seed protectant effects of four essential oils against Callosobruchus maculatus and Callosobruchus chinensis during storage

In many Integrated Pest Management (IPM) programs, many essential oils were recommended to protect plants from insect’s infestations and have few effects on non-target organisms and the environment. Four essential oils (EOs): Ocimum basilicum, Peganum harmala, Anethum graveolens and Lavandula angustifolia were evaluated against two of the most important stored product insect pests, Callosobruchus maculatuc and C. chinensis infesting cowpea seeds during storage. The tested essential oils were obtained by steam distillation methods of dried plants. Effect of Contact toxicity, insecticidal of lethal concentrations, Oviposition deterrent activity, effect on germination and weight loss of seeds of tested oils were experimented on tested insects. The highest conc. 1% achieved (93, 80 and 77%) in the case of O. basilicum, P. harmala, A. graveolens, respectively in the case of C. maculatus. While in C. chinensis 1% conc. achieved, 90, 72 and 67% in the case of O. basilicum, A. graveolens and P. harmala, respectively. The LC50 of tested oils showed that the LC50 of O. basilicum was significantly decreased 4-fold more than lavender oil and O. basilicum is the best oil against C. maculatus and C. chinensis. Cowpea seeds treated with O. basilicum at high rate (1%) showed maximum prevention in oviposition i.e., 99% followed by A. graveolens causing (63 and 55%) prevention in the oviposition of C. maculatus and C. chinensis, respectively. Least weight loss was observed in O. basilicum and A. graveolens in the case of C. maculatus (4.44±0.47 and 8.13 ± 0.32) and C. chinensis (3.14±0.33 and 6.17 ± 0.12), respectively. O. basilicum treatment achieved the highest Feeding Deterrent Index (FDI) of 92.99 and 89.88% in the case of C. chinensis and C. maculatus, respectively. Least (FDI) was recorded in case of L. angustifolia (36.72 and 32.46%) in the case of C. chinensis and C. maculatus, respectively. Our results confirmed that O. basilicum essential oil had an obvious role in suppressing the activity of the tested insects. O. basilicum essential oil can be used in an integrated pest management program as green pesticide and can be effective alternative for chemical pesticides.

Bio-insecticidal and seed protectant effects of four essential oils against Callosobruchus maculatus and Callosobruchus chinensis during storage

In many Integrated Pest Management (IPM) programs, many essential oils were recommended to protect plants from insect’s infestations and have few effects on non-target organisms and the environment. Four essential oils (EOs): Ocimum basilicum, Peganum harmala, Anethum graveolens and Lavandula angustifolia were evaluated against two of the most important stored product insect pests, Callosobruchus maculatuc and C. chinensis infesting cowpea seeds during storage. The tested essential oils were obtained by steam distillation methods of dried plants. Effect of Contact toxicity, insecticidal of lethal concentrations, Oviposition deterrent activity, effect on germination and weight loss of seeds of tested oils were experimented on tested insects. The highest conc. 1% achieved (93, 80 and 77%) in the case of O. basilicum, P. harmala, A. graveolens, respectively in the case of C. maculatus. While in C. chinensis 1% conc. achieved, 90, 72 and 67% in the case of O. basilicum, A. graveolens and P. harmala, respectively. The LC50 of tested oils showed that the LC50 of O. basilicum was significantly decreased 4-fold more than lavender oil and O. basilicum is the best oil against C. maculatus and C. chinensis. Cowpea seeds treated with O. basilicum at high rate (1%) showed maximum prevention in oviposition i.e., 99% followed by A. graveolens causing (63 and 55%) prevention in the oviposition of C. maculatus and C. chinensis, respectively. Least weight loss was observed in O. basilicum and A. graveolens in the case of C. maculatus (4.44±0.47 and 8.13 ± 0.32) and C. chinensis (3.14±0.33 and 6.17 ± 0.12), respectively. O. basilicum treatment achieved the highest Feeding Deterrent Index (FDI) of 92.99 and 89.88% in the case of C. chinensis and C. maculatus, respectively. Least (FDI) was recorded in case of L. angustifolia (36.72 and 32.46%) in the case of C. chinensis and C. maculatus, respectively. Our results confirmed that O. basilicum essential oil had an obvious role in suppressing the activity of the tested insects. O. basilicum essential oil can be used in an integrated pest management program as green pesticide and can be effective alternative for chemical pesticides.

Oviposition deterrence and repellent activities of selected essential oils against Tuta absoluta Meyrick (Lepidoptera: Gelechiidae): laboratory and greenhouse investigations

Tuta absoluta, an invasive pinworm characterized by high reproductive potential and adaptation to different agroecological conditions, cause serious damage to tomato crops. Chemical control with synthetic insecticides is widely used to control this pest, although pesticides exhibit side effects on non-target organisms and negatively impact the environment, with the occurrence of resistance to some active substances in the target pest. The use of essential oils (EOs) from aromatic or officinal plants could represent an environmentally safe control method, alternative to synthetic insecticide application. In this work we investigated the effect of EOs from Spanish oregano, laurel, basil, garlic, peppermint, cypress, and eucalyptus EOs on T. absoluta oviposition deterrence and larval repellency. Results showed a remarkable oviposition deterrence using laurel, Spanish oregano, basil, and garlic EOs in both laboratory and greenhouse experiments. In no-choice repellence tests carried 1, 2, 6, and 22 h after treatment application, peppermint and Spanish oregano EOs showed the most lasting effects while cypress and eucalyptus EOs were not effective after 6 and 22 h, respectively. In choice tests, at either 5 or 22 h after treatment application, low preference for the test over control by larvae was observed in all treatments, except for basil EO. The most promising effects were observed in Spanish oregano and laurel treatments where no larvae were detected. Repellent effectiveness of EOs does not seem to be influenced when larvae did not get a chance to do a choice between treated and untreated leaves. This study highlights the effectiveness of EOs of aromatic or officinal plants as an alternative to synthetic insecticides for the control of T. absoluta.

Oviposition stimulants underlying different preferences between host races in the leaf-mining moth Acrocercops transecta (Lepidoptera: Gracillariidae)

The importance of plant chemistry in the host specialization of phytophagous insects has been emphasized. However, only a few chemicals associated with host shifting have been characterized. Herein, we focus on the leaf-mining moth Acrocercops transecta (Gracillariidae) consisting of ancestral Juglans (Juglandaceae)- and derived Lyonia (Ericaceae)-associated host races. The females of the Lyonia race laid eggs on a cover glass treated with an L. ovalifolia leaf extract; the extract was fractionated using silica gel and ODS column chromatography to isolate the oviposition stimulants. From a separated fraction, two analogous Lyonia-specific triterpenoid glycosides were characterized as oviposition stimulants. Furthermore, we observed probable contact chemosensilla on the distal portion of the female antennae. Lyonia race females laid their eggs on the non-host Juglans after the leaves were treated with a Lyonia-specific oviposition stimulant, although they do not lay eggs on Juglans. These results suggest that Lyonia race females do not lay eggs on Juglans leaves because the leaves do not contain specific oviposition stimulant(s). Otherwise, the activity of the oviposition stimulants overcomes oviposition deterrents contained in Juglans leaves. This paper describes the roles of plant chemicals in the different preferences between host races associated with distantly related plant taxa.

Laboratory studies of oviposition site choice of Toxorhynchites splendens: Role of larval holding-rearing water and predator-prey interactions

Oviposition preference by Toxorhynchites mosquito species is an important aspect of their biological control potential. When ovipositing, the females deposit individual eggs by hovering above the water, indicating that they may be capable of detecting chemical cues from above the water surface. These chemical cues may help the females to determine whether the water is suitable for their larvae. We investigated whether female Tx. splendens has the ability to discriminate against oviposition sites in habitats containing turbid larval/pupal rearing water and predator-prey treatments. In this study, the number of eggs in the test and control cups were compared to assess oviposition preference. According to the results, female Tx. splendens preferred ovipositing in cups with turbid immature water (prey absence) and predator-prey turbid water (prey and predator presences) over ovipositing in filtered water as a control. Results from the third experiment revealed that cups with alive and dead Ae. aegypti larvae proved strongly attractive to Tx. splendens females, while those from conspecific Toxorhynchites larvae caused oviposition deterrence when compared to other treatments in a dual choice test. Our results indicated that both turbid immature water and predator-prey turbid water can efficiently attract Tx. splendens females to deposit eggs. These findings will aid in the development of Toxorhynchites mosquito as a biocontrol agent for the control of Aedes spp. larvae.

Phytochemical and acaricidal study of the Kermani lemongrass, Dracocephalum polychaetum Bornm. (Lamiaceae) essential oil against Tetranychus urticae Koch

ABSTRACT Mites cause significant damage to various crops, often requiring synthetic acaricides for their control. However, the frequent use of these products, resistance problems and severe problems with contamination occur. Therefore, one of the promising solutions is plant acaricides, which can be developed based on essential oils. Thus, the objective of this work was the extraction and characterization of the essential oil from the leaves of Kermani lemongrass, Dracocephalum polychaetum, and acaricidal evaluation of the oil and its major compound using the application by fumigation on female adults of Tetranychus urticae. The composition of the essential oil was analysed by GC-MS. The major components in the oil were 1-octen-3-ol (11.27%), 6-methyl-5-hepten-2-one (11.06%), linalool (9.89), and nonanal (9.64%), respectively. The impact of essential oil of this plant on fumigant toxicity, LT50, oviposition deterrent activity, and repellency against T. urticae was studied at different concentrations. The results stated that D. polychaetum oil had high toxicity on eggs and adults of two-spotted spider mite (LC50 was 60.30 and 50.87 µL L−1 for eggs and adults, respectively) with LT50 of 8.02 h. In addition, all tested concentrations had oviposition deterrent activity and repellency in adults of this mite.

Evaluation of insecticidal activity of Lavandula coronopifolia essential oil against the Mediterranean fruit fly Ceratitis capitata Wiedemann (Diptera: Tephritidae)

The present investigation was aimed to assess the toxicity of Lavandula coronopifolia (Lamiaceae) essential oil (EO) against adult Mediterranean fruit fly. Ceratitis capitata (Wiedemann) (Diptera Tephritidae) is one of the most destructive fruit pests in Morocco.Essential oil was extracted from leaves of lavender (L. coronopifolia) by hydrodistillation and analyzed by GC and GC/MS. The main compound is carvacrol (48.9%) followed by E-caryophyllene (10.8%) and caryophyllene oxide (7.7%).The EO was examined in the laboratory for 7 days to assess their activity against Ceratitis capitata (Wiedemann) (Diptera: Tephritidae) adults by ingestion toxicity. We also conducted oviposition bioassay in the laboratory, testing the oviposition deterrence of essential oils.The oil showed 75% mortality of adults at the concentration of 150 µl/g after 24 h of exposure. Great differences in insect mortality were observed depending on the sex of the insects, oil concentrations and exposure time.The ingestion toxicity potential of L. coronopifolia on adults was higher (LC 50 = 86.34 µl/g, LC 95 = 236.07 µl/g) and also, deterred significantly the oviposition by C. capitata, reducing the number of eggs laid by about 94% compared with the controls for the concentration of 55µl/g.Results suggested that L. coronopifolia EOs may have potential as a control agent against this major stored product insect.

The future of plant volatile organic compounds (pVOCs) research: Advances and applications for sustainable agriculture

Volatile organic compounds emitted by plants (pVOCs) protect themselves from abiotic and biotic stresses. Plants are under constant threats from biotic stress especially herbivores which facilitate plants to emit herbivore-induced plant volatiles (HIPVs), an inducible defense in plants against herbivores by communicating to herbivores’ natural enemies and neighboring plants. HIPVs are reported to act as feeding and/or oviposition deterrents to herbivores, belonging to four major groups including terpene/terpenoids, benzenoids and phenylpropanoids, the volatile fatty acid derivatives, and the volatile aminoacid derivatives. However, the plant volatile profiles induced by herbivores have been reported to be altered by silicon (Si)-fertilization, priming of plants with chemical elicitors and climate change which can induce plants to produce and emit novel plant volatiles that are not expressed by plants in response to damage by herbivory. Transgenic crops and/or sentinel crops with enhanced pVOCs emission profiles have been proposed to improve plant resistance, health and yields. Currently several technological advances in devices including field-portable electronic devices (e-Nose) and hand-held smartphone-based biosensors for in situ early detection of pVOCs profiles which are now available and supported by artificial intelligence (AI), to increase detection accuracy of these systems. The present review highlights the multi-dimension approaches emerging in pVOCs research for early and rapid detection of specific VOCs indicators as markers with associated plant biotic stressors.

Host‐marking pheromone of the South American fruit fly Anastrepha fraterculus and cross‐recognition by the Mediterranean fruit fly Ceratitis capitata (Diptera: Tephritidae)

AbstractFollowing oviposition, females of many fruit flies deposit on the fruit surface a host‐marking pheromone (HMP) that can deter oviposition by conspecifics and heterospecifics, thereby minimizing overexploitation of hosts. We describe the oviposition behaviour of two economically important fruit flies (Anastrepha fraterculus and Ceratitis capitata) in agar spheres marked with methanolic and aqueous faeces extracts that contain the HMP. Laboratory bioassays revealed that A. fraterculus mated female produces an HMP that can be extracted from faeces, and causes a significant reduction in fruit infestation by both conspecifics and heterospecifics (cross‐recognition). Furthermore, mated female faeces extract contains higher amounts of methyl (9E)‐hexadecenoate, methyl hexadecanoate, methyl linoleate and methyl (9Z)‐octadecenoate than male faeces extract. Our results provide evidence for the potential use of this ovipositional deterrent in crop protection and pest management programmes for A. fraterculus and C. capitata.

Live Drosophila melanogaster Larvae Deter Oviposition by Drosophila suzukii.

Simple SummaryThe invasive insect pest, Drosophila suzukii Matsumura or spotted-wing drosophila (SWD) lays its eggs in soft and stone fruit. Eggs hatch into larvae, which feed on fruit, causing fruit collapse and significant economic losses worldwide. Current control methods rely primarily on foliar insecticide applications, which are not sustainable long-term solutions. In nature, D. suzukii interacts with and encounters other Drosophila species, especially towards the end of the growing season when ripening fruits are scarce. We showed previously that D. suzukii were deterred from laying eggs on artificial media exposed to egg laying Drosophila melanogaster, its sister species. It was hypothesized that a signal was left by D. melanogaster which deterred D. suzukii from laying eggs. This study aimed to identify from which D. melanogaster life stage the egg laying deterrent signal originated and we showed that the presence of live D. melanogaster larvae on the egg laying media deter D. suzukii from laying eggs. Drosophila melanogaster cuticular hydrocarbons were examined as the signal source, but no evidence was found for their involvement. These results have improved our understanding of the interspecific interactions between D. suzukii and other Drosophila species and could provide new innovative approaches to D. suzukii management strategies.The worldwide invasive insect pest, Drosophila suzukii Matsumura (spotted-wing Drosophila), lays eggs in soft and stone fruit before harvest. Hatched larvae cause fruit collapse and significant economic losses. Current control methods rely primarily on foliar insecticide applications, which are not sustainable long-term solutions due to regulatory restrictions and the risk of insecticide resistance developing. We showed before that D. suzukii were deterred from laying eggs on artificial media previously visited by its sister species—Drosophila melanogaster. In the current study, laboratory choice test experiments were conducted to identify which D. melanogaster life stage (eggs, larvae, or adult) deterred D. suzukii oviposition. We demonstrated that the presence of live D. melanogaster larvae on the egg-laying media consistently deterred D. suzukii oviposition. Drosophila melanogaster cuticular hydrocarbons (CHCs) were examined as candidate for the oviposition deterrent. CHCs of larval and adult D. melanogaster and D. suzukii were analyzed. In both species, the composition of the CHCs of larvae was similar to that of adults, although quantities present were much lower. Furthermore, the CHC profiles of the two species were markedly different. However, when assayed as deterrents in the laboratory choice test experiment, CHC extracts from D. melanogaster did not deter oviposition by D. suzukii.

Laboratory-based toxicity of scale insect pathogen Moelleriella raciborskii (Zimm.) (Hypocreales: Clavicipitaceae) crude extracts and isolated compounds against Tetranychus truncatus Ehara (Acari: Tetranychidae)

Tetranychus truncatus is a phytophagous spider mite that is one of the economic pests of agricultural and economic crops. Its control has been and still is based mainly on the use of chemical controls. Since pesticides compatibility with natural enemies is a main concern for IPM programs, the aim of this study was carried out to explore the toxicity, repellency, oviposition deterrent and eggs hatching inhibition of crude ethyl acetate extract of Moelleriella raciborskii and their secondary metabolites against adults and eggs of T. truncatus. The results indicated that M. raciborskii crude extract at 5% (w/v) had high contact toxicity (89% mortality) on adult females of T. truncatus. The LC50 value was 1.476%, 1.026 and 0.732% after 24, 48 and 72 h posttreatment. Among the two steroidal and two hopane triterpenes separated from the ethyl acetate extract, 3β-acetoxy-15α,22-dihydroxyhopane was identified as the most active compound with LC50 values of 0.232% (w/v), followed by ergosterol, ergosterol 5, 8-endoperoxide with LC50 values of 0.235% and 0.318% at 72 h posttreatment, respectively. In addition, 3β-acetoxy-15α,22-dihydroxyhopane showed strong repellency (70.19%) and ergosterol and ergosterol 5, 8-endoperoxide decreased egg production of T. truncatus by 70.35 and 67.98%, respectively. Strong oviposition deterrent (ODI=100) was noted when 0.5% (w/v) crude extract was applied on half of the leaf disc. The crude ethyl acetate extract of M. raciborskii could have potential for the development of novel acaricides to control T. truncatus for use in an integrated pest management program.

Neem-Based Insecticides Deter Oviposition Activity in Spotted Wing Drosophila (Diptera: Drosophilidae) in Sweet Cherries.

Spotted wing drosophila, Drosophila suzukii (Matsumura), is an important invasive insect pest in the United States. Spotted wing drosophila females have serrated ovipositor that enables them to deposit eggs inside healthy, ripening softskinned fruits. In many berry and fruit crops, spotted wing drosophila is primarily controlled using synthetic insecticides in the organophosphate, pyrethroid, and spinosyn groups. However, alternative, reduced-risk insecticides with short residuals are necessary to minimize the possibilities of insecticide resistance and address other negative effects of synthetic insecticides. Neem-based products as alternative plant-based insecticides have antifeedant, repellent, antiovipository, and molting interference effects on insects and have been shown to affect the oviposition activities of some tephritid flies. We conducted laboratory studies to evaluate the oviposition deterrent activities of selected neem-based insecticides that contain either azadirachtin, or CHENO, or a combination of both, on spotted wing drosophila using sweet cherry in California. The results of the study showed that some of the neem oil products could reduce the degree of spotted wing drosophila oviposition by half compared with the control.

Repellent and oviposition-deterrent efficacies of Cuscuta chinensis on filarial vector Culex quinquefasciatus

In the laboratory, crude and chloroform: methanol extracts of Cuscuta chinensis seeds were evaluated for repellence and oviposition deterrence activities against adults of Culex quinquefasciatus at various concentrations. Hundred percent protection was attained from a 99% concentration of chloroform: methanol extract for 120 minutes whereas from the crude extract for the first 90 minutes with a gradual decrease. Crude and chloroform: methanol extracts of seeds were found to be highly effective in preventing oviposition of adult mosquitoes. Furthermore, neither extract has any negative side effects such as allergy or other observable reactions on human skin during or after the exposure period. Oviposition activity index (OAI) was negative at all concentrations for tested plant extracts which indicated an inhibition of Cx. quinquefasciatus oviposition. So, against Cx. quinquefasciatus mosquito species, crude and chloroform: methanol seed extracts of C. chinensis may be utilized as a repellent and oviposition deterrent.

Deterrent Activity of Natural Products on Two Spotted Spider Mite <i>Tetranychus urticae</i> Koch

The feeding inhibition and oviposition deterrent activity of natural products were evaluated under laboratory conditions against Tetranychus urticae Koch. Mite feeding specks in the treatments varied from 61.3 to 428 at concentrations ranging from 0.625 to 40%. Darekastra and fermented buttermilk outperformed others to result in reduced number of feeding specks with increase in concentration. The feeding inhibition index for all the products was negative suggesting that these have varied level of inhibition. Cow urine, Darekastra, fermented buttermilk and Tamarlassi were found to effectively reduce the oviposition by mite. The oviposition deterrence index exhibited both attractiveness and repellent activity of natural products. Cow urine, Darekastra and fermented buttermilk proved as potent acaricides against T. urticae under both the deterrence parameters.

Oviposition Deterrent Activity of Fungicides and Low-Risk Substances for the Integrated Management of the Olive Fruit Fly Bactrocera oleae (Diptera, Tephritidae).

Simple SummaryThe olive fruit fly Bactrocera oleae is a very common pest infesting olive orchards wherever they are cultivated, representing the greatest threat to olive production and oil quality. Although broad-spectrum insecticides are often used to protect olive crops against B. oleae, there is increasing concern about their effects on the environment and human health. An important tool in integrated olive fly management could be the use of products with a repellency and oviposition deterrence effect. This research yielded experimental evidence of significant oviposition deterrent activity on the olive fly as side effects of substances used in olive growing such as fungicides or plant biostimulants, highlighting the potential use of these products in B. oleae management.The control of Bactrocera oleae is fundamental to decreasing the significant production loss in olive cultivation. However, traditional containment based on the use of synthetic insecticides has been encountering serious limitations due to their negative effect on human health and the environment. Within the scope of integrated olive fly management, the use of products with repellency and oviposition deterrent activity might represent a more eco-friendly solution. In this study, we tested the oviposition deterrent activity of some commercial formulations already used in olive tree crops as fungicides (copper oxychloride, dodine, mancozeb, pyraclostrobin and difeconazole) and plant bio-stimulants (tannins, clay, flavonoids and a zinc-copper-citric acid biocomplex). The trials were conducted testing the oviposition behavior of mated olive fly females in both choice and no-choice assays. Our results showed that most of the substances have affected the ovipositional activity of the olive fly, except for difeconazole. Moreover, some products (copper oxychloride, flavonoids and tannins) have proven to differently influence the flies’ oviposition comparing the two tests. The repellent effect of these commercial products should be further studied to prove whether the repellency was due either to the active ingredient or to the co-formulants, and to assess their effect in the open field.