Douglas M. Light

A pear-derived kairomone with pheromonal potency that attracts male and female codling moth, Cydia pomonella (L.)

Abstract. Ethyl (2E, 4Z)-2,4-decadienoate, a pear-derived volatile, is a species-specific, durable, and highly potent attractant to the codling moth (CM), Cydia pomonella (L.), a serious pest of walnuts, apples, and pears worldwide. This kairomone attracts both CM males and virgin and mated females. It is highly attractive to CM in both walnut and apple orchard contexts, but has shown limited effectiveness in a pear orchard context. Rubber septa lures loaded with ethyl (2E, 4Z)-2,4-decadienoate remained attractive for several months under field conditions. At the same low microgram load rates on septa, the combined gender capture of CM in kairomone-baited traps was similar to the capture rate of males in traps baited with codlemone, the major sex pheromone component. The particular attribute of attracting CM females renders this kairomone a novel tool for monitoring population flight and mating–ovipositional status, and potentially a major new weapon for directly controlling CM populations.

Enhancement of Insect Pheromone Responses by Green Leaf Volatiles

verfahren wird fiir jede Beaufort-St/irkestufe und jedes Jahrzehnt durchgefiihrt, so dab man als Funktion der Zeit far jede Beaufort-St/irke einen Betrag des Luftdruckgradienten erh/ilt. Diesen kann man, etwa mit der heute am besten bestimmten Skala [5], auf Windgeschwindigkeit umrechnen. Damit ist die Umrechnung der Beaufort-St/irkeSch/itzungen friiherer Jahrzehnte auf Windgeschwindigkeiten m6glich. Es sei noch darauf hingewiesen, dab unsere Methode unabh/ingig yon der H~iufigkeitsverteilung des Windes in einem Seegebiet ist, da sie getrennt ftir jede Beaufort-Stufe durchgeftihrt wird. Die sich in einem Gebiet nach der Rekonstruktion ergebenden Wind~inderungen kOnnen daher als lokale Klima/inderungen angesehen werden. Als Beispiel wird hier die rekonstruierte Zeitreihe des Windes aus dem Feld vor der brasilianischen Kiiste wiedergegeben (Fig. 3). W/ihrend man von 1880 bis 1940 eine Zunahme um 0,5 m/s findet, ist nach 1950 praktisch kein von Null verschiedener Trend festzustellen. Diese Aussage gilt speziell fiir das Eingegangen am 17. Oktober 1989

Electroantennogram responses of the mediterranean fruit fly,Ceratitis capitata, to a spectrum of plant volatiles

Electroantennograms (EAGs) were recorded from unmated, laboratory-reared, male and femaleCeratitis capitata (medfly) in response to a range of C1 and C2 to C12 carbon chain-length aliphatic alcohols, aldehydes, acetates, and acids, and lactones, some of which are known volatiles from leaves and fruits. A large degree of EAG response uniformity between the sexes was observed, with only eight of the 70 compounds tested eliciting significantly larger amplitude EAG responses from female than male antennae. In general, for the five functional-group series tested, aldehydes and alcohols elicited greater responses than acetates, lactones, and acids. The unsaturated alcohols, aldehydes, acetates, and acids elicited equal or larger amplitude EAG responses than their comparable saturated compounds. For four of the functional-group series tested, the EAG response amplitude was significantly greater for a particular carbon chain length, with responsiveness to primary alcohols and aldehydes peaking at C6, acids peaking at C5–6, and acetates peaking at both C5 and C8. The EAG responses to both the 2- and 3-position monoenic alcohols peaked at C6 and C8, while the secondary alcohols peaked at C7. The greatest EAG responses of all compounds tested were elicited by monoenic C6 alcohols and aldehydes that are constituents of the “general green-leaf odor” that emanates from most plants. The potential adaptive benefit of selective sensitivity to green-leaf volatiles is discussed in regard to foraging behavior of medflies.

Attractants from Bartlett pear for codling moth, Cydia pomonella (L.), larvae

Abstract. The alkyl ethyl and methyl esters of (2E,4Z)-2,4-decadienoic acid found in head-space samples of ripe Bartlett pear (Pyrus communis L.) stimulated a response from neonate larvae of the codling moth (CM), Cydia pomonella (L.), in both static-air Petri-plate and in upwind Y-tube and straight-tube olfactometer bioassays. In comparison with the known CM neonate attractant, (E,E)-α-farnesene, ethyl (2E,4Z)-2,4-decadienoate was attractive at 10-fold and 1,000-fold lower threshold dosages in the Petri-plate and in the Y-tube bioassays, respectively. Methyl (2E,4Z)-2,4-decadienoate was attractive to CM neonates in these bioassays at much higher doses than ethyl (2E,4Z)-2,4-decadienoate. Other principal head-space volatiles from ripe pear fruit and pear leaves, including butyl acetate, hexyl acetate, (Z)-3-hexenyl acetate, and (E)-β-ocimene, were not attractive to CM neonates. The potential uses of these pear kairomones for monitoring and control of CM in walnuts and apple are discussed.

Electroantennogram responses of the Mediterranean fruit fly, Ceratitis capitata to identified volatile constituents from calling males

Fifty‐six compounds from the odor of ‘calling’, sexually mature, laboratory reared males of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae)*** were isolated by headspace trapping on Tenax columns and identified using GC/MS techniques (69 total compounds were detected). Electroantennogram responses (EAGs) to 54 of the 56 identified compounds as well as 5 analogs were tested on both sexes. Significant differences between the sexes in their responsiveness were found in 9 of the 54 identified compounds tested. There was no correlation between the amplitude of the EAG response and the relative abundance of compound identified from headspace analysis. Of the five ‘major’ identified components, three elicited relatively small EAG responses, while two elicited large EAGs compared to the hexan‐1‐ol standard. The relative ranking of EAG responses were: methyl and ethyl hexenoates and hexanoates > C4‐C6 esters and/or acetates > ethyl and methyl octenoates > monoterpenes > sesquiterpenes > C2‐C5 acetates, alcohols and ketones. Behavioral bioassays on each of the five ‘major’ identified components as well as a blend of six of the compounds showed some degree of attractancy to virgin females which in some cases approached the response to a ‘pheromonal’ standard (male odors absorbed onto filter paper). These results are discussed in relationship to the insects antennal sensitivity to putative ‘pheromone’ components and/or allomonal components and to other reported C. capitata pheromone studies.

Monitoring codling moth (Lepidoptera: Tortricidae) in apple with blends of ethyl (E, Z) -2,4-decadienoate and codlemone

Abstract Studies evaluated blends of the pear-derived kairomone ethyl (E, Z)-2,4-decadienoate and codlemone, loaded in gray halobutyl septa, as attractants for adult codling moth, Cydia pomonella L. Studies were conducted in apple orchards, Malus domestica Borkhausen, treated with or without sex pheromone dispensers for mating disruption (MD). Septa were loaded with either one or both compounds at rates of 0.0, 0.3, and 3.0 mg pear ester and 0.0 and 3.0 mg codlemone in the first series of tests. Traps baited with a 3.0/3.0-mg blend caught significantly more males and total number of codling moths than traps baited with either compound alone in both types of orchards. Traps baited with two lures loaded individually with pear ester (3.0 mg) and codlemone (3.0 mg) caught significantly fewer males and total moths than traps baited with the dual lure (3.0/3.0 mg). The addition of 3.0 mg codlemone to pear ester did not significantly affect the capture of female moths. However, increasing the loading of pear ester from 0.3 to 3.0 mg in the dual lure significantly increased female moth catch in the untreated orchard but not in the sex pheromone MD orchard. Increasing the loading of pear ester to 20.0 mg in a dual lure with 3.0 mg codlemone significantly increased total codling moth catch compared with a 3.0 mg codlemone lure, but female catch was significantly lower compared with traps baited with a 3.0 mg pear ester lure. Adding a 3.0 mg pear ester lure to traps baited with a 42.0 mg sex pheromone lure significantly reduced male moth catch compared with the sex pheromone lure alone but did not reduce the catch of female moths compared with traps baited with a 3.0 mg pear ester lure alone.

Attraction of female mediterranean fruit flies to the five major components of male-produced pheromone in a laboratory flight tunnel.

Attraction and pheromonal activity of five major identified components of the male-produced sex pheromone of the Mediterranean fruit flyCeratitis capitata to virgin laboratory-reared females was assessed in a laboratory flight tunnel. Dual-choice competitive assays were run to establish a baseline response of virgin females to live male pheromone, individual components, and an ensemble of all five compounds alone (air control) and competitively against one another. Approximately 50% of the females released in the tunnel were captured on leaf models emitting pheromonal odors from five live males. Over 37% of released females responded to an ensemble of five major identified components presented in individual capillaries. Response of females to individual components was less than 10%. Competitive assays showed the live male-produced pheromone to be more attractive than either the five major component ensemble (FMCE) or individual components. Further research is likely to identify other male-produced compounds with pheromonal activity that could improve development of a pheromone-based trap for monitoring Mediterranean fruit fly populations.

Factors Affecting the Differential Capture of Male and Female Codling Moth (Lepidoptera: Tortricidae) in Traps Baited with Ethyl (E, Z)-2,4-Decadienoate

Abstract Studies were conducted in apple to evaluate factors that differentially affect the catch of male and female codling moth, Cydia pomonella L., in traps baited with ethyl (E, Z)-2,4-decadienoate (pear ester). We examined the time of moth capture in the diel cycle and the recapture rates of marked moths in sex pheromone mating disruption (MD) and untreated orchards. The attractiveness of pear ester–baited traps was compared among five apple cultivars. Experiments also assessed the influence of trap height, the distance of the trap from sex pheromone dispensers, proximity of foliage surrounding the trap, trap size, and proximity of adjacent clean and codling moth–injured fruit on moth captures. The responses of male and female moths significantly differed in response to many of these factors. For example, the time of peak female capture occurred earlier than for males. A higher proportion of recaptured, marked moths were females in MD versus untreated orchard plots. Significantly more male but not female moths were caught in traps placed high versus low in the tree canopy. Traps placed on the perimeter of the canopy caught significantly more female moths than traps placed within the canopy and surrounded by foliage. Smaller trap surfaces caught significantly more males than females. Traps placed adjacent to uninjured fruit caught significantly more females than traps placed away from fruit. No differences occurred between sexes in response to other factors: significantly higher counts of both sexes occurred in blocks of ‘Granny Smith’ versus four other apple cultivars; recapture rates of marked moths were not different at release points ranging from 10 to 50 m for either sex; and trap placement relative to MD dispensers or injured versus uninjured fruits was not a significant factor affecting moth catches or their sex ratio. Effective monitoring for either or both sexes of codling moth should consider standardizing these factors. Lure and kill strategies should include factors that optimize the captures of female moths.

Behavioral Responses of Female Oriental Fruit Flies to the Odor of Papayas at Three Ripeness Stages in a Laboratory Flight Tunnel (Diptera: Tephritidae)

Behavioral responses of adult female oriental fruit flies, Dacus dorsalisHendel, to the odor of papayas from three ripeness classes were studied using a threechoice flight tunnel bioassay. Laboratoryreared flies were allowed to respond freely to any of three papaya odors (mature green, colorbreak to one-fourth ripe, and one-half to full ripe) emanating from identical (spherical) fruit models. Five behaviors were measured in assessing the flys relative attraction to the odors (number of landings), arrestment (total fly seconds on sphere), fly-fly interactions on the fruit model (maximum and modal fly density), and acceptance for oviposition (total eggs laid). Females showed no significant difference in total fly landings based on all age classes combined. Significant differences were noted among age classes. Females spent more total time on the sphere and showed a higher maximum density and modal fly density to ripe fruit than to green fruit odors. Ovipositional acceptance of fruit models based on the total number of eggs laid in a sphere was greater in response to the ripefruit odor than to the other two odor classes. Olfactorystimulated behavioral responses of females to the odor of ripe papayas were significantly different from the other ripeness classes for all behaviors at 8 days postemergence and then declined in 11-day-old flies. Behavioral responses were greater during the afternoon than in the morning. Observations of wild oriental fruit flies to papayas in the field indicated a preference for residing on riper fruit. The results of this study are discussed with regard to the role of olfactory inputs generated by the odor of ripening fruit on female attraction and oviposition behavior resulting in infestation of papayas by oriental fruit fly.

Seasonal Flight Patterns of Codling Moth (Lepidoptera: Tortricidae) Monitored with Pear Ester and Codlemone-baited Traps in Sex Pheromone-Treated Apple Orchards

Abstract Traps baited with ethyl (E, Z)-2, 4-decadienoate (pear ester) or (E, E)-8,10-dodecadienol (codlemone) were used to monitor codling moth, Cydia pomonella L., (Lepidoptera: Tortricidae) in 102 apple, Malus domestica Borkhausen, orchards. All orchards were treated with 500–1,000 Isomate-C PLUS dispensers/ha during 2000–2002. Traps baited with pear ester caught their first moth significantly later on average than the paired codlemone-baited traps, but timing of peak moth catch during each moth flight coincided with both types of lures. The timing of first male moth capture in pear ester–baited traps was significantly earlier than the first female moth; and the percentage of male moths in the total numbers of moths captured ranged from 55 to 60% over the three seasons. The percentage of female moths caught by pear ester–baited traps that were mated exceeded 80% each year. Pear ester–baited traps caught similar numbers of moths as codlemone-baited traps during 2000. However, the density of sex pheromone dispensers per hectare was increased in most orchards in 2001–2002; and pear ester outperformed codlemone-baited traps in both years.