Ayhan Gökçe

Behavioral and Electrophysiological Responses of Leafroller Moths to Selected Plant Extracts

Abstract The behavioral and electrophysiological responses of the obliquebanded leafroller, Choristoneura rosaceana (Harris), and the redbanded leafroller, Argyrotaenia velutinana (Walker), to crude extracts of Arctium lappa, Bifora radians, Humulus lupulus, Xanthium strumarium, and Verbascum spp. were studied under laboratory conditions. Plant materials were dried and ground before extraction with methanol. Plant extract residues were mixed in acetone to give 20% (wt:wt) suspensions after evaporation of excess methanol. All five plant extracts elicited significant electroantennogram (EAG) responses from both males and females of each species. EAG responses to X. strumarium were generally the highest for both species. The behavioral responses of male and female obliquebanded leafrollers to the plant extracts were compared with responses to pheromone [(Z)11–14:Ac] and a solvent control. Significantly more male and female obliquebanded leafrollers were attracted to X. strumarium compared with pheromone on filter paper, H. lupulus, Verbascum spp., and the control. Compared with the control, there was no significant attraction to pheromone on filter paper, A. lappa, H. lupulus, and Verbascum spp. The oviposition-deterring effect of plant extracts on female obliquebanded leafrollers was studied in dual-choice bioassays. B. radians elicited the highest oviposition deterring effect with no eggs laid on this treatment. A. lappa was also effective and reduced oviposition to 2.9% of that observed in the controls. The number of eggs laid on X. strumarium (14.4%) and Verbascum spp. (21.2%) treatments were not significantly reduced relative to the control; however, oviposition was reduced by three-fold by these two treatments. The results show that certain crude plant extracts induce behavioral effects on male and female obliquebanded leafrollers. Further studies are needed to determine the active ingredients and their potential use in pest management strategies aimed at managing these pest species in tree fruit production.

Contact and residual toxicities of 30 plant extracts to Colorado potato beetle larvae

Abstract Contact and residual toxicities of 30 plant extracts were investigated on third instar larvae of Colorado potato beetle, Leptinotarsa decemlineata. The plant samples were collected during the spring and summer of 2002 and were dried and ground. The plant samples were treated with methanol and the residue was eluted with distilled water containing 10% acetone, resulting in plant extracts. In contact bioassays, the beetle larvae were treated with 40% (w/w) plant extract using a Potter Spray Tower. The insects were incubated at 28±2°C under a 16 h: 8 h photo regime and the mortality was recorded at 24 h intervals for 7 days. The plant extracts exhibited varying toxicity to the larvae ranging from 0 – 91% after 24 h incubation and Artemisia vulgaris, Hedera helix, Humulus lupulus, Lolium temulentum, Rubia tinctoria, Salvia officinalis, Sambucus nigra, Urtica dioica, Verbascum songaricum, and Xanthium strumarium extracts resulted in significantly higher mortality than the control. Generally, prolonged incubation time did not result in an increase in mortality. After 48 h of incubation, 10 plant extracts yielded a significant mortality and H. lupulus extract, the most toxic extract among those tested, caused 99% mortality which is similar the mortality caused by the chemical standard, imidacloprid. In residual assays, potato leaflets were treated with 20% (w/w) plant-extract concentrations using a Potter Spray Tower. Third instar larvae were added to a glass jar to which treated leaflets were transferred before incubation at the temperature and photo regime described above. Mortality was recorded at 24 h intervals for 7 days. Five plant extracts, H. lupulus, L. temulentum, Reseda lutea and Solanum nigrum, induced significantly higher mortalities compared with controls. Chenopodium album extract was the most toxic, killing 34.9% of exposed larvae, followed by L. temulentum, H. lupulus and S. nigrum after 72 h incubation. The results exhibited that certain plant extracts were toxic to the beetle larvae and may have potential for controlling this destructive pest under field conditions.

Toxicity and Antifeedant Activity of Selected Plant Extracts Against Larval Obliquebanded Leafroller, Choristoneura rosaceana (Harris)

Several plant extracts were evaluated against obliquebanded leafroller larvae to determine potential toxicity and antifeedant effects. Two of the plant extracts exhibited contact toxicity; the LC50 value of Humulus lupulus extract against 3 rd insar larvae was 24.5 μg / insect. In a no choice context, larval survivorship was reduced 23 - 57 % after feeding on a meridic pinto bean diet treated with the extracts. Furthermore, average female and male pupal weight was reduced for lea- frollers that fed on diet treated with each of the individually-tested extracts at a 4 % concentration (w/w). Incorporation of Bifora radians and H. lupulus into diet deterred larval feeding at a 1 % concentration by weight. H. lupulus and Arctium lappa extracts were deleterious to larvae in each of the bioassay methods conducted, exhibiting toxic, developmental, and antifeedant effects. These two extracts may be promising candidates for further development as botanical insecticides that could potentially substitute broad-spectrum synthetic neurotoxins for leafroller control.

Novaluron causes reduced egg hatch after treating adult codling moths, Cydia pomenella: Support for transovarial transfer

Abstract The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is a primary pest of apples throughout the United States. Reliance on broad spectrum organophosphates has been declining with the slated cancellation and has shifted towards narrow spectrum insecticides. Novaluron, a chitin synthesis inhibitor, has primarily been used for its ovicidal and larvacidal activities. However, recent studies have demonstrated a transovarial effect after exposure to adults. The effects of novaluron were studied to determine if reduced egg hatch occurs after exposure of different sexes to this compound. Effects of this compound through horizontal transfer were also compared with a topical application to C. pomonella eggs. Results from independent exposure of different sexes to novaluron were different than the control for all three exposure types; male only, female only, and both treated. The horizontal transfer experiment yielded no significant difference while the topical application of novaluron on eggs showed significantly lower egg hatch. Although novaluron has no direct toxicity to adults, the results of this study demonstrate that the delayed lethal activity of this compound reduces hatching of eggs laid by treated adults. Along with the direct ovicidal and larvicidal properties of novaluron, the delayed lethal activity provides an important contribution to the overall control seen in the field.

Reduced egg viability in codling moth Cydia pomonella (L.) (Lepidoptera: Tortricidae) following adult exposure to novaluron

BACKGROUND The codling moth, Cydia pomonella (L.), is one of the principal pests of pome fruits in the world. The effects of novaluron, a benzoylurea chitin synthesis inhibitor insecticide registered for use on apples in the USA, on fecundity and egg viability in codling moth were studied under laboratory conditions. Three different exposure methods were investigated: ingestion, contact and topical spray. Additionally, the duration of novaluron sublethal effects was measured subsequent to the three modes of exposure. RESULTS The fecundity of codling moth adults was not significantly affected by novaluron with any of the exposure methods. However, novaluron did cause significant reductions in the proportion of egg hatch with all three exposure methods. The duration of sublethal effects was 9 days or more for all modes of exposure, but with the topical spray these effects began to diminish after 6 days. CONCLUSION Novaluron does not affect fecundity in codling moth, but has significant sublethal activity by reducing egg viability subsequent to adult exposure. The topical, contact and ingestion exposures all induce sublethal effects after exposure, and these persist to various degrees throughout codling moth oviposition. A more complete understanding of novalurons lethal and sublethal activities will help IPM practitioners optimize its use for management of the codling moth.

Behavioural and electrophysiological responses of grape berry moth (Lep., Tortricidae) to selected plant extracts

Abstract:  Four non‐host plant extracts from Bifora radians, Arctium lappa, Humulus lupulus and Xanthium strumarium, were tested against adult grape berry moths, Paralobesia viteana, for their potential as repellents or oviposition deterrents. Responses were compared with those elicited by the major component of the P. viteana sex pheromone. Moths of both sexes exhibited varying electroantennogram (EAG) responses from 1.7 to 2.4 mV to volatile odours from plant extracts, with the greatest response to extracts of H. lupulus (2.4 mV). A multi‐arm olfactometer was used to assay the behavioural response of moths to the same treatments. Male moths responded significantly to H. lupulus extract, although their strongest response was to the sex pheromone (30.0%). Female moths showed no behavioural response to the sex pheromone, attracting only 6.7% of moths, but they were attracted to extracts of H. lupulus, X. strumarium and A. lappa, with 25.0%, 21.7% and 15.0% of the released insects responding to these treatments, respectively. Choice tests were conducted to compare oviposition by P. viteana on untreated grapes and on grapes treated with one of the extracts. Despite the attraction in the olfactometer assays, H. lupulus extract significantly reduced egg laying; only 12.5% of the total deposited eggs were laid on berries treated with this extract. The extract of B. radians provided complete protection against oviposition.

Dose–response relationships for the antifeedant effects of Humulus lupulus extracts against larvae and adults of the Colorado potato beetle

BACKGROUND Dose-response relationships for antifeedant effects of H. lupulus extracts against larvae and adults of the Colorado potato beetle (CPB) were determined in laboratory conditions. The larval and adult beetles were fed on potato leaflets treated with H. lupulus extract ranging from 0.4 to 40 mg mL(-1) in a no-choice situation. Their feeding behavior was recorded, and larval growth and antifeedant indexes were calculated. RESULTS H. lupulus treatments significantly affected larval growth rate, and at higher concentrations the larval weights were significantly reduced over the course of the assay. Adults of CPB were more sensitive to the extracts than the larvae, and, even at lower doses, adult beetles were arrested for longer periods than larvae. CONCLUSION These results indicate that H. lupulus extracts may have potential for control of CPB, particularly in organic farms where conventional insecticides are not available.

Ovicidal, larvicidal and anti-ovipositional activities of Bifora radians and other plant extracts on the grape berry moth Paralobesia viteana (Clemens)

Methanol extracts of Bifora radians, Arctium lappa, Humulus lupulus and Xanthium strumarium were tested against the North American grape berry moth, Paralobesia viteana in laboratory and greenhouse assays. Egg hatch was reduced by B. radians and X. strumarium extracts, whereas larval mortality was observed in response to B. radians, X. strumarium and A. lappa. Given the high mortality against egg and larval stages of this pest caused by extracts of B. radians, further studies were performed to determine the dose–response relationships between extracts of this plant and oviposition and egg hatch of P. viteana. There was a significant reduction in egglaying and egg hatch with increasing extract concentration, with 0.1% extracts providing 80% mortality and 1% extracts causing more than 90% control. This study demonstrates the potential of this plant extract for crop protection against a key pest of grapes and suggests that additional crop pests and field tests should be pursued to determine the efficacy of B. radians extracts as a biopesticide.

Tanacetum abrotanifolium (L.) Druce (Asteraceae) ekstraktlarının Sitophilus granarius ile Sitophilus oryzae (Coleoptera: Curculionidae)’ye uzaklaştırıcı etkilerinin zorunluluk testleri ile belirlenmesi

Repellent effects of Tanacetum abrotanifolium (L.) Druce (Asteraceae) stem and flower extracts were tested against Sitophilus granarius (L.) (Granary weevil) and S. oryzae (L.) (Rice weevil) (Coleoptera: Curculionidae) under laboratory conditions. Repellent effects of plant extracts were tested in no-choice set up. The stem and flower extracts were obtained using three different solvents that were hexane, ethyl acetate, and methanol. In no-choice set up, the most pronounced repellent activity was seen with the stem ethyl acetate extract (58.96%) for the rice weevil and with the stem ethyl acetate extract (71.40%) for the granary weevil. These results indicate that T. abrotanifolium has a potential in the control of both S. granarius and S. oryzae especially in the grain stores .