Júlia Katalin Jósvai

No evidence for behavioral responses to circularly polarized light in four scarab beetle species with circularly polarizing exocuticle

The strongest known circular polarization of biotic origin is the left-circularly polarized (LCP) light reflected from the metallic shiny exocuticle of certain beetles of the family Scarabaeidae. This phenomenon has been discovered by Michelson in 1911. Although since 1955 it has been known that the human eye perceives a visual illusion when stimulated by circularly polarized (CP) light, it was discovered only recently that a stomatopod shrimp is able to perceive circular polarization. It is pertinent to suppose that scarab beetles reflecting LCP light in an optical environment (vegetation) being deficient in CP signals may also perceive circular polarization and use it to find each other (mate/conspecifics) as until now it has been believed. We tested this hypothesis in six choice experiments with several hundred individuals of four scarab species: Anomala dubia, Anomala vitis (Coleoptera, Scarabaeidae, Rutelinae), and Cetonia aurata, Potosia cuprea (Coleoptera, Scarabaeidae, Cetoniinae), all possessing left-circularly polarizing exocuticle. From the results of our experiments we conclude that the studied four scarab species are not attracted to CP light when feeding or looking for mate or conspecifics. We demonstrated that the light reflected by host plants of the investigated scarabs is circularly unpolarized. Our results finally solve a puzzle raised over one hundred years ago, when Michaelson discovered that scarab beetles reflect circularly polarized light.

Female-targeted attractant containing pear ester for Synanthedon myopaeformis

When testing pear ester (ethyl‐2,4‐decadienoate) + acetic acid (PEAA) lures to catch codling moths, Cydia pomonella (L.) (Lepidoptera: Tortricidae), in Hungary, significant catches of the apple clearwing moth, Synanthedon myopaeformis (Borkhausen) (Lepidoptera: Sesiidae), were also recorded. This sesiid is one of the most important pests of apple in Europe. Pear ester plus acetic acid lures were attractive to S. myopaeformis no matter whether the two compounds were provided in separate dispensers or mixed together in a single dispenser, and a large percentage (40–80%) of the clearwing moths caught were females. In all cases, traps baited with binary combinations of PEAA caught far more than traps baited with either of the compounds presented alone. Traps with PEAA lures in some tests caught (females and males together) up to ca. 20% of the catch in traps baited with the synthetic apple clearwing moth sex attractant (all males). Consequently, the PEAA lure shows potential for future practical applications as a female‐targeted lure. To our knowledge, this is the first report of attractiveness of a lure containing pear ester for non‐tortricid Lepidoptera. Our finding suggests that the compound may be exploited as a host location stimulus by a wider array of insects than was indicated previously.

Traps baited with pear ester and acetic acid attract both sexes of Hedya nubiferana (Lepidoptera: Tortricidae)

This study was initiated with the objective of studying field responses of the green budworm moth, Hedya nubiferana (Haworth) (Lepidoptera: Tortricidae), to pear ester [PE; ethyl (E,Z)‐2,4‐decadienoate] and acetic acid (AA) with the aim of developing a lure attractive also for females. In the overwhelming majority of tests, traps baited with the PEAA lure (the combination of both PE and AA) caught more than traps baited with either of the constituents presented alone. PEAA lures were attractive to H. nubiferana no matter whether the two compounds were provided in separate dispensers or mixed together in a single one, and a large percentage (up to 71%) of trap catch consisted of females. Traps with PEAA lures caught (females plus males) on an average 30% of the catches in traps baited with the synthetic green budworm moth sex pheromone (only males). This suggested that the new PEAA lure had a trapping performance comparable with that of pheromone traps, which latter are used by farmers today. Consequently, the PEAA lure showed potential for future practical applications as a female‐targeted lure for H. nubiferana. To our knowledge, this is the first well‐documented report on the attraction of PEAA lure for a tortricid species other than codling moth.

Pheromone races of Cydia splendana (Lepidoptera, Tortricidae) overlap in host plant association and geographic distribution

Identification of the sex pheromone of Cydia splendana (Lepidoptera, Tortricidae) by pheromone gland analysis followed by field trapping with synthetic compounds shows the occurrence of two pheromone races. Acorn moth females from Sweden, where oak Quercus robur is the only host plant, use a blend of the E,Z and E,E isomers of 8,10-dodecadien-1-yl acetate. In Central and Southern Europe, where C. splendana feeds on chestnut Castanea sativa and several species of oak, males respond to another isomer blend, E,E and Z,E. The distribution of the two pheromone races of C. splendana overlaps in Northern France, where they share oak as plant host. Differences in sex communication signals lead to behavioural pre-mating isolation between these populations, and emphasize the role of specific mate recognition in speciation events.

Combining odours isolated from phylogenetically diverse sources yields a better lure for yellow jackets.

BACKGROUND Invasive wasps have major impacts on bird populations and other biodiversity in New Zealand beech forests, and new solutions are needed for their management. Baits were combined from four phylogenetically diverse sources (protein and carbohydrate) to improve attraction to a level that could be used as the basis for more powerful attract-and-kill systems. Many compounds from honey, scale insect honeydew, fermenting brown sugar and green-lipped mussels were highly attractive and, when combined, outcompeted known attractants. RESULTS The equivolumetric lure (equal parts of 3-methylbut-1-yl acetate, 2-ethyl-1-butanol, 1-octen-3-ol, 3-octanone, methyl phenylacetate and heptyl butanoate), gave a 5-10-fold improvement over the known attractant, octyl butanoate, and other previously patented lures. An economically optimised lure of the same compounds, but in a ratio of 2:1.6:1:1:2:2.4, was equally attractive as the equal-ratio lure. Pilot mass trapping attempts with this latter lure revealed that >400 wasps trap(-1) day(-1) could be caught at the peak of the season. CONCLUSION The new lures are comprised of compounds from animals, plants and fungi, thus targeting the omnivorous behaviour of these wasps.

Microlepidoptera caught in traps baited with lures containing pear ester and acetic acid in Hungary

The present research was undertaken to screen for field activity of ethyl-(E,Z)-2,4-decadienoate (pear ester, PE), acetic acid (AA) and the blend of this two components (PEAA) at locations, where high diversity of microlepidopteran species was presumed. By tendency of relative catches, microlepidopterans captured could be divided into two groups: in the first group the PEAA blend resulted in higher catches than single components (Hedya nubiferana, Ypsolopha scabrella and Notocelia trimaculana), while in the second group (Archips rosana, A. xylosteana, Ptycholoma lecheana and Tortrix viridana) only the presence of AA was responsible for attractivity. In all species, both male and female specimens were caught. This result indicates a potential way to optimise female-targeted lures based on PEAA or AA for all these microlepidopterans that are all recorded as pests. On the other hand, the capture of the above moths in the traps raises the need for some taxonomic knowledge in evaluating captures in PEAA-baited...

Associative Learning of Food Odor by Social Wasps in a Natural Ecosystem

The ability of insects to associate olfactory cues with food from their environment has been well documented with various insect orders. However, these studies were based on prior training of insects to associate odors with food sources in the laboratory or in the field with almost no evidence for the development of this phenomenon in natural ecosystems. In New Zealand’s ancient Fuscospora spp. or beech forests, invasive Vespula social wasps were attracted to odor from honeydew (benzaldehyde and n-octanol) but did not respond to a known wasp attractant (isobutanol and acetic acid). On the other hand, wasps in a rural/suburban area in New Zealand did not respond to honeydew odor but responded instead to the known wasp attractant. Similarly, social wasps in Hungary did not respond to honeydew odor, but responded to the known wasp attractant. DNA sequences of Vespula vulgaris from the two locations in New Zealand were 100% identical. Similarly, DNA sequences of V. germanica from the two locations in New Zealand were 100% identical, indicating little or no intra-specific variation. On the other hand, DNA sequences of V. vulgaris and V. germanica from New Zealand were 99.56 and 99.78% matches with V. vulgaris and V. germanica samples from Hungary, respectively. Electroantennogram (EAG) response profiles of wasps from the three locations to benzaldehyde, isobutanol, acetic acid, n-octanol and heptyl butyrate were similar. The high similarity in DNA sequences and EAG profiles, with only a behavioral difference in the response to odor sources, suggests that social wasps in New Zealand’s beech forest have naturally developed associative learning for the odor of the carbohydrate-rich honeydew. This is the first study to provide conclusive evidence of the occurrence and the development of associative learning of food odor by social insects in a natural ecosystem free of human interference. The ability of social wasps to naturally develop associative learning of food odor might in part explain why they are extremely successful invaders of new ecosystems, especially those with rich honeydew resources. The finding of our study will have significant implications for the use of attractants in wasp monitoring and control in different habitats.

Identification of the Female-Produced Sex Pheromone of an Invasive Greenhouse Pest, the European Pepper Moth (Duponchelia fovealis)

The European pepper moth (Duponchelia fovealis, Lepidoptera, Crambidae, Spilomelinae) is an invasive pest of greenhouses in many countries, causing serious damages to horticultural plants. Coupled gas chromatographic-electroantennographic detection analysis of the female gland extract revealed two antennally active peaks. Using coupled gas chromatography–mass spectrometry (GC-MS), one was identified as (Z)-11-hexadecenal (Z11–16:Ald); however, further analysis on different types of capillary columns indicated that the second active compound has two different isomers, (E)-13-octadecenal (E13–18:Ald) and (Z)-13-octadecenal (Z13–18:Ald). The approximate ratio of E13–18:Ald, Z13–18:Ald and Z11–16:Ald in the crude pheromone gland extract was 10:1:0.1, respectively. Single sensillum recordings showed that there was one sensory neuron that responded with a high amplitude spike to both E13–18:Ald and Z13–18:Ald, while another neuron housed in the same sensillum responded to Z11–16:Ald. Field evaluation of the identified compounds indicated that the E13–18:Ald was necessary to evoke the attraction of males; although the presence of Z13–18:Ald and Z11–16:Ald increased the catches in traps. The highest number of caught males was achieved when E13–18:Ald, Z13–18:Ald and Z11–16:Ald were present in baits in the same ratio as in the female gland extract. This pheromone can be used in a monitoring strategy and could potentially lead to the development of mating disruption.

A pear ester‐based female‐targeted synthetic lure for the chestnut tortrix, Cydia splendana

One of the most important insect pests of the chestnut acorn, Castanea sativa Miller (Fagaceae), is the chestnut tortrix, Cydia splendana H€ ubner (Lepidoptera: Tortricidae), which is present in several European countries such as Hungary, Greece, Italy, France, and Turkey (B€ urg es, 1973; Fr erot et al., 1995; Speranza, 1999; Karagoz et al., 2009; Avtzis et al., 2013). Fruit losses caused by this moth can range from 20 to 70% (den Otter et al., 1996) depending on the year and plantation. Thus, monitoring of the seasonal flight and population density is important for the management of this pest moth, which is difficult due to the large canopy of the trees (Avtzis et al., 2013). Sex pheromone-related compounds of C. splendana have been identified from female gland extracts (Fr erot et al., 1995). In field experiments, blends of synthetic (E,E)and (E,Z)-8,10-dodecadien-1-yl acetate were found to be attractive to male moths (Witzgall et al., 1996). Although the ratio of these two components in the most effective blend was different in the northern vs. the southern parts of Europe (Bengtsson et al., 2014), these two synthetic acetates as pheromone lures were successfully applied for monitoring of the male chestnut tortrix (Delisle et al., 2005; Lopes et al., 2008). A lure capable of catching females in addition to males would have significant advantages over the use of traps baited with the sex pheromone, which attract only males. This is particularly important because egg-laying and peak-hatching period of young larvae is expected to be more closely associated with female flight patterns (Knight & Light, 2004, 2005a). A volatile compound from ripe pear, ethyl (E,Z)-2,4-decadienoate (pear ester, PE), was described as a strong kairomonal attractant for both sexes of a closely related tortricid, the codling moth, Cydia pomonella L. (Light et al., 2001). Attraction of C. splendana to PE was also reported by Schmidt et al. (2007). In Hungary, industrial chestnut monoculture plantations are rare. Instead, commercial harvests are performed in forest-like natural biotopes in several regions of the country (Rad ocz & B€ urg es, 2004). In general, populations of C. splendana are modest in such biotopes. Probably due to this, we failed to record sizeable catches in preliminary trials with PE (M. T oth & E. Voigt, unpubl.). We therefore concluded that PE was not active enough as an attractant in our conditions and felt the need for an improved female-targeted lure. Landolt et al. (2007) showed that the addition of acetic acid (AA) to PE acted synergistically on C. pomonella catches. This finding was confirmed in North American (Knight, 2010) as well as European studies (T oth et al., 2012). More recently, the addition of AA to PE was found to increase catches in some other moths belonging to the Tortricidae (Hedya nubiferana H€ ubner; J osvai et al., 2016) or Sesiidae (Synanthedon myopaeformis Borkhausen; T oth et al., 2012). The present work was initiated to verify whether the addition of AA to PE would improve the attraction of female C. splendana. Another aspect of the study was to compare catches of PEAA to that of sex pheromone (PH) lures to assess their performance for population monitoring. This work was aimed at developing an improved female-targeted lure for the species.