Free-choice Test Research Articles

Rats show up to 72h of significant retention for spatial memory in the radial maze.

This study explored long-term retention of spatial memory in rats using an eight-arm radial maze. Crystal and Babb (Learning and motivation, 39(4), 278-284, 2008) previously demonstrated that rats could retain spatial memory for up to 25h in the radial maze. Notably, they found performance improved with 48-h intertrial intervals compared with 24-h intervals. Our study investigated the effects of extending intertrial intervals on long-term retention of spatial memory by reducing the potential for proactive interference. Each trial comprised a learning phase, during which subjects were required to sequentially visit four randomly selected arms, followed by a free-choice test that included all eight arms, conducted after increasing the retention and intertrial intervals. The retention intervals were systematically increased from 1h to 24, 48, and, ultimately, 72h, with corresponding intertrial intervals expanding from 24 to 48, 120, and 144h. Performance significantly surpassed chance levels across all conditions, demonstrating that rats are capable of retaining spatial memory for up to 72h.

Impact of vanilla flavor on nicotine taste, choice, intake, and seeking behaviors.

Flavors can alter the orosensory properties of tobacco products. Specifically, flavors can serve as an oral cue for smokeless tobacco products. We aimed to investigate the impact of oral vanillin, the principal chemical of vanilla flavor in tobacco products, on nicotine's taste, and nicotine choice, intake, and seeking behaviors. Experiments were performed in young adult Sprague Dawley rats. We employed a two-bottle free-choice test (2BC) to measure the preference for different concentrations of vanillin and its effect on nicotine preference. To explore the long-term effects of early exposure to sweetened vanillin, we utilized a combined 2BC and intraoral self-administration (IOSA) model. We assessed the nicotine taking and seeking behaviors in the presence or absence of vanillin. We performed a taste reactivity test (TRT) to quantify liking (ingestive) and disliking (aversive) taste responses to oral nicotine with or without vanillin. In 2BC, female rats preferred vanillin containing solutions more than their male counterparts. In IOSA, vanillin alone and in combination with nicotine led to greater IOSA compared to water. Female rats self-administered vanillin plus nicotine more than male rats. Vanillin increased motivation to nicotine taking, but only in females. In TRT, vanillin increased nicotine's ingestive responses but blocked aversive responses in both sexes. These results indicate that vanilla flavor can increase oral nicotine intake. It can also increase liking and decrease disliking of nicotine's taste. Furthermore, the impact of vanilla flavor on nicotine taste and nicotine choice, intake, and seeking behaviors is concentration and sex dependent.

Ovipositional Preference of <i>Rhynchophorus ferrugineus</i> (Olivier) in Palm Species in Goa

Red palm weevil (RPW) Rhynchophorus ferrugineus (Olivier) (Coleoptera: Curculionidae) is devastating pest in commercial and ornamental palms. The study was conducted to find out ovipositional preference of R. ferrugineus in seven palm species. Result revealed that the fish tail palm (Caryota cumingii Lodd.) is highly preferred host for oviposition by R. ferrugineus followed by coconut (Cocos nucifera L.). Toddy palm (Borassus flabellifer L.) was found to be least preferred by R. ferrugineus for oviposition. The ornamental palm, cane palm Dypsis lutescens (H. Wendl.) Beentje and J. Dransf is found as new preferred host for oviposition in free choice test.

The feeding and foraging behaviour of three ladybird beetles on Phenacoccus solenopsis (Hem.: Pseudococcidae) at different temperatures

ABSTRACT Ladybird beetles Scymnus nubilus Mulsant, Scymnus interruptus (Goeze), and Hippodamia convergens Guérin-Méneville are key contributors to biological control of some pests including Phenacoccus solenopsis Tinsley. This study explores their feeding preferences, functional response, and interference in controlled laboratory conditions. Feeding experiments, including both no-choice and free-choice tests, were conducted at temperatures ranging from 15 to 35°C fed on different developmental stages of P. solenopsis. The study analyzed the functional response with Holling's disc equation and assessed mutual interference among predators using the Hassell and Varley model. In the no-choice feeding tests, H. convergens adults exhibited the highest consumption at 26°C, with values of 46.0 1st instar nymphs, 40.9 2nd instar nymphs, and 34.9 adult females of P. solenopsis, followed by S. interruptus. Free-choice feeding tests also showed a preference for 26°C, with H. convergens consistently consuming the most prey at all stages, followed by S. interruptus. Functional response analysis revealed a type II functional response for three predators. Hippodamia convergens exhibited a significantly higher attack rate (1.0250 h−1) and a shorter handling time (0.0449 h) compared to the other species. Interference among predators was observed, with a progressive decline in prey consumption as predator density increased. Mutual interference constants (m) were calculated as 1.70, 1.74, and 1.77 for S. nubilus, S. interruptus, and H. convergens, respectively. As predator densities increased, searching efficiency declined. This suggest that H. convergens and S. interruptus adults at 26°C with a prey density of 40 can effectively contribute to sustainable P. solenopsis management.

The oviposition preference and offspring performance of Aethina tumida (Coleoptera: Nitidulidae).

Given the rapid spread and potential harm caused by the small hive beetle, Aethina tumida (Coleoptera: Nitidulidae) in China, it has become imperative to comprehend the developmental biology of this invasive species. Currently, there is limited knowledge regarding the impact of A. tumida female oviposition site preference on larval growth and development. To examine this, we investigated the ovipositional preference of adult female A. tumida on bee pupae, beebread, banana, and honey through a free choice test. Furthermore, we assessed the impact of these food resources on offspring performance, which included larval development time, survival, wandering larvae weight, emerged adult body mass, reproduction, and juvenile hormone titer. Our results showed that A. tumida females exhibited a strong preference for ovipositing on bee pupae compared to other diets, while showing reluctance toward honey. Moreover, A. tumida larvae that were fed on bee pupae displayed accelerated growth compared to those fed on other diets. Furthermore, A. tumida fed on bee pupae exhibited higher weights for wandering larvae, and emerged adult, increased pupation rates, enhanced fecundity and fertility, as well as a larger number of unilateral ovarioles during the larval stage when compared to those fed on other diets. Overall, the results indicate that the oviposition preferences of A. tumida females are adaptive, as their choices can enhance the fitness of their offspring. This finding aligns broadly with the hypothesis of oviposition preference and larval performance. This study can provide a foundation for the development of attractants aimed at promoting the oviposition of the A. tumida adults.

Influence of Physico-chemical Traits of Chickpea Genotypes on Preference and Non-preference of Pulse Beetle, Callosobruchus maculatus (Fab.)

Background: Chickpea is one of the most important and nutritionally rich pulse crops widely grown in India. Pulse beetle is a cosmopolitan insect pest that can cause significant losses in stored chickpeas. Host Plant Resistance, one of the most effective methods, being adopted for decades to identify the traits in the host plants that confer resistance against the insect pests. The present study has been undertaken to screen different genotypes of chickpea against pulse beetle and to understand the influence of physico-chemical traits of chickpea genotypes on the population buildup of pulse bruchid. Methods: Twenty chickpea genotypes including thirteen desi and seven kabuli type were screened against pulse beetle through free choice test at Department of Entomology, Agricultural College, Bapatla during 2020-21. Certain physical and biochemical parameters of chickpeas were assessed and the level of their influence on growth and development of pulse bruchid was estimated by correlation and regression analyses. Result: The desi chickpea genotypes viz., NBeG 452, NBeG 1129, ICC 86111, NBeG 49 and NBeG 776 with less oviposition, less number of adults emerged, less grain damage were found relatively with less test weight, total soluble sugars and more seed coat thickness, total phenols and tannins and the kabuli genotypes viz., NBeG 440, NBeG 789 and NBeG 833 with more oviposition, more number of adults emerged, more grain damage were found relatively with more test weight, total soluble sugars and less seed coat thickness, total phenols and tannins. Thus, test weight, total soluble sugars exhibited significant positive correlation with growth and damage parameters of pulse beetle, while the seed coat thickness, total phenols and tannins exhibited significant negative correlation. Despite the fact that the biochemical components of the genotypes of chickpea varied significantly, they had little effect on the development of pulse bruchid.

Discovery and properties of novel analogues of the aphid pheromones nepetalactone and nepetalactol.

Pheromones have unique advantages for pest control. Current aphid pheromone research focuses on alarm and sex pheromones. However, practical applications are limited so far, as (E)-β-farnesene has only been investigated to a small extent as an alarm pheromone and only male aphids are targeted by sex pheromones. Previous literature reports electrophysiological responses and repellent behavior of asexual aphids to nepetalactone (1B), therefore our objective was to modify nepetalactone's structure to identify key fragments responsible for repellent effects, as guidance for subsequent modifications and further investigation. In this study, seven derivatives were designed and synthesized based on nepetalactol (1A) and nepetalactone (1B) as lead compounds. Free-choice tests, conducted using cowpea aphids (Aphis craccivora), revealed that the lactone moiety was crucial for the repellent activity, and the removal of the carbonyl group eliminated the repelling effect. Compound (±)1I, an analogue of nepetalactone (1B), demonstrated a significantly higher repellent value than nepetalactone (1B) at three different concentrations, and even at 0.1 mg/mL it maintained a considerable repellent effect (26.5%). Electrostatic potential and density functional theory calculations supported the importance of the carbonyl group for the repellent effects. The newly discovered para-pheromone (±)1I shows improved repellent effects and potential for development as a novel biological control agent. Based on our innovative findings, analogues with improved efficacy and properties can be designed and prepared. Our research contributes to understanding the effects of structural modifications on pheromone activity and properties, which is crucial for exploring novel pheromone-based products for crop protection. © 2024 Society of Chemical Industry.

Resistance of dwarf Cocos nucifera L. (Arecaceae) cultivars to Raoiella indica Hirst (Acari: Tenuipalpidae).

The red palm mite Raoiella indica Hirst, 1924 (Acari: Tenuipalpidae) is an important pest of the coconut palm Cocos nucifera L. (Arecaceae) and has caused problems in coconut production worldwide. Research has been carried out aiming at controlling the mite through chemical, biological, alternative, and host plant resistance methods. Identifying coconut palm cultivars resistant to R. indica is important to reduce the problems caused to plantations. Therefore, the objective of this work was to evaluate the performance of R. indica in six dwarf coconut palm cultivars, to identify sources of resistance. The cultivars of the sub-varieties green, red, and yellow evaluated were Brazilian Green Dwarf-Jiqui (BGDJ), Brazilian Red Dwarf-Gramame (BRDG), Cameroon Red Dwarf (CRD), Malayan Red Dwarf (MRD), Brazilian Yellow Dwarf-Gramame (BYDG), and Malayan Yellow Dwarf (MYD). Confinement and free choice tests of R. indica on the cultivars were performed, in which biological parameters and preference were evaluated. Mite performance was different in the cultivars evaluated. In the confinement bioassay, R. indica had the worst performance in the cultivar BGDJ, the best performance in CRD, MRD, and BRDG, and intermediate performance in BYDG and MYD. In the free choice test, the cultivars MRD and MYD were preferred in relation to BGDJ, and CRD was less preferred in relation to BGDJ. Therefore, we considered that the cultivar BGDJ is the most resistant to R. indica, by antibiosis and antixenosis; CRD has resistance by antixenosis; and MRD, BRDG, BYDG, and MYD are susceptible.

Antixenosis and antibiosis mechanisms of resistance to Asian rice gall midge, Orseolia oryzae (Wood‐Mason) in rice land races

AbstractAsian rice gall midge is one of the important pests of rice, which attacks the crop from nursery to the end of the tillering stage. Managing this pest through plant resistance is the most viable and economical. Two hundred‐two rice genotypes were phenotyped against Asian rice gall midge, Orseolia oryzae (Wood‐Mason) and the mechanism of resistance in terms of antixenosis and antibiosis was studied. Antixenosis mechanism for adult settlement and egg laying indicated that the susceptible genotypes were preferred more than the resistant genotypes in a free choice test. First instar maggots were found and did not continue their growth on resistant genotypes further. However, in susceptible genotypes, they molted successfully and emerged as adults. No choice tests revealed that the emergence of adults in susceptible genotypes took less time than in resistant genotypes. Higher adult sex ratio was found in susceptible genotypes. Estimation of biochemical components in rice shoot apices of selected genotypes revealed that higher levels of total phenols, wax content, total flavonoids and total free amino acids were present in the resistant genotypes. Still, the number of total sugars, reducing sugars and total protein contents were significantly higher in the susceptible genotypes. Hence, the resistance mechanism in rice gall midge was displayed as a combination of antixenosis and antibiosis mechanism. The output of the study would be helpful in breeding for rice varieties resistant to Asian rice gall midge.

Developing A Solid Termite Bait Matrix and Conducting Efficacy Trials Under Lab and Semi Field Conditions

The study on development of solid termite bait matrix and its efficacy against the Heterotermes indicola was performed in Peshawar, during 2023. The study was performed with completely randomized design (CRD) with different treatments i.e., developed bait, patent bait, popular wood and blotting paper. Each treatment was replicated three times. The laboratory experiment consisted of no-choice, free choice and aggregation test. While the semi-field experiment consisted of free choice test. During the no-choice test of the laboratory experiment, H. indicola showed a consumption rate of 6.29% for the popular wood and developed bait. However, in the blotting paper treatment, the termites consumed only 2.81%. In terms of choice test conducted in the lab, the popular wood exhibited the highest weight consumption percentage of 2.87%, while the patent bait displayed the lowest weight consumption percentage of 2.25%. Under the choice test maximum number of termites were attracted towards popular wood (77.00 Number of termites) while minimum number of termites were attracted towards patent bait (54.66 Number of termites). Whereas, in aggregation test, of the lab experiment, maximum number of termites were also aggregated towards popular wood (37.77 Number of termites) while minimum termites were aggregated for patent bait (25.22 Number of termites). In the case of free choice under semi-field conditions, the highest number of termites were observed on popular wood i.e., 380.00 followed by the developed bait, which recorded 293.50 termites. On the other hand, the lowest number of termites were recorded on the patent bait i.e., 231.50. Similarly, when considering the maximum consumed weight in percentage, popular wood exhibited the highest value at 16.24%, closely followed by the developed bait at 15.67% while the patent bait displayed minimum consumed weight percentage of 12.89%. In overall experiments it is concluded that among all the tested treatments, termites mostly consumed popular wood and developed bait. Since the developed bait showed promising results in attracting termites, it is recommended to continue refining its formulation. Conduct additional research to identify the key components or additives that enhance its attractiveness and consumption by termites. This optimization process can help maximize the effectiveness of the bait as a termite control strategy. Adding more popular wood saw dust in the bait may achieve more significant and desired results and can also prove to be cost efficient rather than adding more cellulosic material.

Screening of Soybean Advanced Breeding Lines for Resistance Against the Southern Green Stink Bug Nezara viridula L (Hemiptera: Pentatomidae) under Free-Choice and No-Choice Tests

Background: The southern green stink bug (SGSB), Nezara viridula, is a potentially harmful pod sucker insect found in soybean. Objective: The objective of this study was to evaluate the resistance level of several soybean advanced breeding lines against the southern green stink bug N. viridula under the free-choice and no-choice tests. Methods: The research materials were 14 advanced breeding lines and four check cultivars. The experiment was conducted in Malang, East Java, Indonesia, during the dry season I and II 2022. The resistance evaluation of the soybean genotypes against the N. viridula was under the Free-Choice test (FC) and the No-Choice test (NC). The newly emerged adults N. viridula were infested when plants reached the R5 stage. The data were observed for damage intensity, yield and yield components. Results: The intensity of pod damage in the FC ranged from 20.09 to 46.40%, meanwhile, in the NC was 25.63 to 67.63%. This shows that the NC condition provides more selection pressure than the FC. Each genotype exhibited different resistance reactions in the FC and NC. The pod damage intensity had a significant negative correlation with seed yield both in the FC and NC. Conclusion: The No-Choice test (NC) provided a higher selection pressure for resistance to SGSB than the Free-Choice test (NC). The use of SGSB-resistant cultivars will prevent soybean seed yield losses. A new finding in this study, two soybean genotypes Anj/Rjbs-305 and Anj/Rjbs-306 were resistant to SGSB. Both genotypes exhibit good agronomic performance (high yield and large seed size), thus can be proposed as new soybean varieties to be developed in the country.

Sensitivity to the role of an animated agent from observed interactions in newborn chicks (Gallus gallus).

Few month old human infants are able to detect the social roles of artificial agents and consistently choose the object behaving as 'approacher' rather than 'repulser'. This preference has been considered evidence of a pre-linguistic and pre-cultural origin of the social mind. Similar preferences have not been described in other species, though comparative data could help clarify the nature of this phenomenon and its evolutionary origin. In this study, we investigated sensitivity to the social role of an artificial agent in domestic chicks. Birds offer an excellent model to study the evolutionary roots of cognitive abilities, since they separated from mammals over 300 Ma. Moreover, the investigation of newly hatched chicks allows control for previous experience. After being exposed to computer-presented animations depicting an interaction among two agents, chicks underwent a free choice test among those same objects. While no initial evidence of a clear preference emerged from the planned analysis, chicks in the experimental condition showed a preference for the 'approacher' when controlling for side bias, mirroring human infants behaviour. This suggests the existence of an early ability to discriminate agents from their interactions, independent from any social experience.

Oviposition Preference and Age-Stage, Two-Sex Life Table Analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Different Maize Varieties

Host plants play an important role in the growth, development, and reproduction of insects. However, only a few studies have reported the effects of maize varieties on the growth and reproduction of S. frugiperda. In this study, a free-choice test was used to evaluate the oviposition preferences of female adults on ten common maize varieties and ten special maize varieties. The population fitness of S. frugiperda on six different maize varieties was also examined using the age-stage, two-sex life table method. The results showed that S. frugiperda oviposited and completed its life cycle across all maize cultivars. Moreover, the S. frugiperda females exhibited a significantly higher oviposition preference on the special maize varieties than on the common maize varieties. The highest number of eggs and egg masses occurred on Baitiannuo and the lowest on Zhengdan 958. The egg + larval stage, preadult, pupal stage, adult, APOP, TPOP, and total longevity of S. frugiperda were significantly shorter on the special maize varieties than on the common maize varieties. The fecundity, oviposition days, pupal weight, and hatching rate of S. frugiperda were significantly higher on the special maize varieties than on the common maize varieties. Specifically, S. frugiperda had the highest fecundity, female, and male pupal weight on Baitiannuo. Moreover, the net reproductive rate (R0), intrinsic rate of increase (r), and finite rate of increase (λ) of S. frugiperda were the greatest on Baitiannuo, whereas the shortest mean generation time (T) occurred on Zaocuiwang. The lowest R0, r, and λ, and longest T occurred on Zhengdan 958, suggesting that Zhengdan 958 is a non-preferred host plant compared to the other tested maize varieties. The findings of this study can provide a reference for the rational planting of maize and provide basic scientific information for the management of S. frugiperda.

Preference and Preformance of <i>Bemisia tabaci</i> (Gennadius) on Different Host Plants

Host preference and development biology of Bemisia tabaci (Gennadius) on brinjal, soybean, cucumber, cotton, tomato and Solanum nigrum L. was studied during 2020-21 at PAU, Ludhiana. Under free choice test conditions, cucumber was the most preferred host which attracted maximum number of adults followed by soybean. The other host plants in decreasing order of preference were cotton > brinjal > tomato > S.nigrum. Brinjal and cotton were the most suitable hosts having shorter development period, higher survival and fecundity. The survival of immature stages on soybean was 50% as compared to 67.5-72.5% on the most suitable hosts i.e. cotton and brinjal. Thus, soybean is a preferred host for adult feeding andoviposition but less suitable for immature stages of the B. tabaci. Hence, soybean may be exploited as atrap crop for the management of B. tabaci.

Sphenophorus levis Behavior Studies: Evaluating Insect Attractiveness or Repellency to One Insecticide Treatment and Assessing Nocturnal Insect Activity and Location Pattern

Sphenophorus levis Vaurie, 1978 (Coleoptera: Curculionidae). is a difficult to control pest in sugarcane that causes great damage to the subterranean part of the plant. Low insect control is the result of the pesticide application technology adopted but also a consequence of the lack of studies regarding the pest's behavior. This research aimed to examine the attractiveness and repellency of one labelled insecticide dose to S. levis adults and to evaluate the activity and location behavior of S. levis adults under hourly observations over 24 h. Repellency and attractiveness studies were conducted in free-choice tests with treated soil with an insecticide product composed of lambda-cyhalothrin + thiamethoxam active ingredients and untreated soil. Insect activity and location behavior studies were assessed by conducting hourly observations of S. levis adults in containers with soil and sugarcane plant. The results indicate that S. levis adults are not repelled nor attracted to soil treated with the labelled dose of lambda-cyhalothrin + thiamethoxam in sugarcane. Additionally, insects presented nocturnal behavior for most activities (walking, digging and mating) starting at 6:00 p.m. until 2:00 a.m. An average of 21% of insects were out of the soil at night while the majority, 79%, remained inside the soil. During the day, most insects, 95%, remained hidden in the soil. Exposed insects were primarily located on the soil surface. According to these results, nocturnal insecticide applications may improve S. levis adult control due to greater insect activity and exposure at night.

Uji Ketahanan Galur Jambu Mete Terhadap Hama Helopeltis sp. (Hemiptera: Miridae)

<p><em>One of the causes of low cashew productivity in production centers is the attacks by pest, especially the mosquito bug </em>Helopeltis<em> </em><em>sp. (Hemiptera: Miridae). Control efforts can be done by using the resistant varieties. The study was conducted at Cikampek Experimental Farm, from January–December 2018. This study aims to determine the level of resistance of crossbred cashew (F1) against </em>Helopeltis<em> sp. using the free-choice test method. The study was arranged in a Randomized Group Design and repeated 2 times. Total of 50 crossbred cashew strains propagated by grafting were placed in cages in a circular position. The number of plants in each cage was 23 strains. A total of 5 pairs adult of </em>Helopeltis<em> sp. that had been fed for 2 hours were introduced and placed in the center of the cage. The observation began 2 days after </em>Helopeltis<em> sp. infested which repeated every 3 days for 1 month or stopped if the insects died. Parameters observed included the number of eggs laid, number of eggs hatched, number of </em>Helopeltis<em> sp. perched, attack intensity, number of shoots, number of leaves grown and length of recovery period. The results showed that 23 strains were tolerant to </em>Helopeltis<em> sp., namely numbers: 2.1, 5.3, 6.4, 7.1, 7.3, 8.1, 9.1, 10.3, 11.4, 13.3, 13.4, 14.1, 15.1, 17.1, 18.1, 19.1, 19.3, 21.1, 21.3, 22.3, 22.4, 24.1, and 25.4. The attack intensity was 10-87.5 %. At the time of recovery, shoot growth reached 1-4 shoots and leave growth reached 2-11 leaves. The recovery period occurred for 10-14 days. The yield of the tolerant strains obtained required for further testing in the field.</em></p>

Dinâmica populacional de Drosophila suzukii em vinhedo e susceptibilidade de cultivares viníferas

Abstract Grapes are not considered a good host for the spotted-wing drosophila, Drosophila suzukiiHowever, its damage results in qualitative and quantitative losses to the wine grapes berries. Knowing the D. suzukii population dynamics in vineyards and surrounding areas, as well as the wine cultivars susceptibility, can help winegrowers to carry out the management. The objective of this study was evaluate the D. suzukii population dynamics in the field, on the forest border present around the vineyard and in its interior and evaluate the susceptibility of the main wine cultivars for São Joaquim municipality to the attack of D. suzukii in laboratory. In the vineyard, D. suzukii was monitored from November 2018 to May 2021 with weekly inspections. Plastic pot traps with a red stripe baited with the Droskidrink attractant were used, distributed among the vines and around the vineyard. Monitoring data were correlated with regional climate variables. In laboratory, through non-choice and free-choice test, the susceptibility to D. suzukii damage was evaluated in Chardonnay, Sauvignon Blanc, Sangiovese, Cabernet Franc, Cabernet Sauvignon and Merlot berries. Intact and artificially injured berries were offered to adults in plastic screened cages for 24h. Afterwards, the number of punctures, eggs, emerged adults and the period of egg-adult development were evaluated. The data were analyzed in the R environment. Through monitoring, it was found that the presence of D. suzukii adults was higher in the forest border (762) in the surroundings compared to inside of the vineyard (128). The precipitation reduced the population of D. suzukii inside the vineyard, while the average and maximum temperatures promoted an increase in the population. In free choice tests, the cultivar Sangiovese was susceptible to the attack and development of D. suzukii. The cultivar Cabernet Sauvignon showed reduced egg-adult development time compared to the other tested cultivars in no-choice test.

Antifeedant Potential of Geranylacetone and Nerylacetone and Their Epoxy-Derivatives against Myzus persicae (Sulz.).

Geranylacetone and nerylacetone are natural sesquiterpenoids, which play various roles in plant-insect interactions, including the deterrent and repellent effects on herbivores. The structural modifications of natural compounds often change their biological activities. The aim of the study was to evaluate the effect of geranylacetone, nerylacetone and their epoxy-derivatives on the probing and settling behavior of Myzus persicae (Sulz.) (Hemiptera: Aphididae). The no-choice test using the Electrical Penetration Graph (EPG) technique showed that the probes before the first phloem phase were usually shorter than 3 min, which means that they were terminated within the epidermis and/or outer layers of mesophyll. This resulted in a tendency to delay the initiation of the phloem phase in aphids, which reflects a weak preingestive deterrent activity of the studied compounds at the level of non-vascular tissues. Most M. persicae showed bouts of sustained phloem sap ingestion. However, the 24-h free-choice test demonstrated that aphids did not settle on the leaves treated with geranylacetone, nerylacetone, and their epoxy-derivatives. The refusal to settle after the consumption of phloem sap on treated plants indicated that the studied compounds had postingestive deterrent activity. The epoxidation of geranylacetone and nerylacetone did not evoke significant changes in their activity profiles.

Is there hierarchical generalization in response-effect learning?

Ideomotor theory is an influential approach to understand goal-directed behavior. In this framework, response-effect (R-E) learning is assumed as a prerequisite for voluntary action: Once associations between motor actions and their effects in the environment have been formed, the anticipation of these effects will automatically activate the associated motor pattern. R-E learning is typically investigated with (induction) experiments that comprise an acquisition phase, where R-E associations are presumably learned, and a subsequent test phase, where the previous effects serve as stimuli for a response. While most studies used stimuli in the test phase that were identical to the effects in the acquisition phase, one study reported generalization from exemplars to their superordinate category (Hommel et al., Vis Cogn 10:965–986, 2003, Exp. 1). However, studies on so-called R-E compatibility did not report such generalization. We aimed to conceptually replicate Experiment 1 of Hommel et al. (Vis Cogn 10:965–986, 2003) with a free-choice test phase. While we did observe effects consistent with R-E learning when the effects in the acquisition phase were identical to the stimuli in the test phase, we did not observe evidence for generalization. We discuss this with regard to recent studies suggesting that individual response biases might rather reflect rapidly inferred propositional knowledge instead of learned R-E associations.

Leaf consumption and oviposition of Palpita forficifera (Lepidoptera: Crambidae) on different olive cultivars

The incidence of the olive caterpillar Palpita forficifera is among the main phytosanitary problems in olive groves in Brazil, and the use of resistant cultivars can be a useful tool to be incorporated into an integrated management strategy of this pest. The objective of this study was to evaluate the consumption and oviposition of P. forficifera on three olive cultivars in laboratory bioassays, in order to identify a potential antixenosis-type resistance. The cultivars evaluated were Arbequina, Arbosana and Koroneiki. Oviposition free choice tests were carried on young trees of the cultivars, with 7 days old adults. For consumption, detached leaves from the different cultivars were used in no choice and free choice tests with 5th instar larvae. The oviposition of P. forficifera was similar in all three cultivars. As for consumption, in no choice test, Arbequina had a higher dry mass consumed, yet, in free choice tests, no significant difference was observed in the fresh and dry mass consumed on the three cultivars. These results suggest that none of the cultivars expressed antixenosis-type resistance.