ATTRACTION of AUSTRALIAN Carpophllus SPP. (COLEOPTERA: NITIDULIDAE) to SY:"Ithetic PHEROMONES and FERMENTING BREAD DOUGH DA
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7206 1. Aus!. en!. Soc.. 1993.32: 339·345 339 ATTRACTION OF AUSTRALIAN CARPOPHlLUS SPP. (COLEOPTERA: NITIDULIDAE) TO SY:"iTHETIC PHEROMONES AND FERMENTING BREAD DOUGH DAVID G. JAMES', ROBERT J. BARTELT', RICHARD J. FAULDER' and ANN TAYLOR' 'NSW Agricullure. Yanco AgricullUrallnslilule. PMB Yanco. NoS. W. 2703. 'USDA Agricullural Research Sen-ice. Nalional Cenler jor AgricullUral Ulilisalion Research. 1815 N. Uni\'ersiIY 51 .. Peoria, Illinois, 6/604. U.S.A. Abstract Data are presented on the attraction of nitidulid beetles (primarily Carpophilus spp.) to synthetic aggregation pheromone, pheromone plus fermenting bread dough or dough alone. in an apricot orchard in southern New South Wales during November· March. The combination of pheromone and bread dough was significantly more effective than either type of bait alone. Synthetic pheromone of Carpophilus hemiplerus (L.) increased attraction of this species to dough by 115 times. Low order (1.7·3.2 times increase) cross·attraction of Carpophi/us mutilatus Erichson. Carpophi/us davidsoni Dobson and Carpophilus (Urophorus) humeralis (F.) also occurred to the combination. Synthetic pheromone of C. mUlilatus increased the attraction of this species to dough by up to 17 times and appeared to be most effective early in the season. C. davidsoni and C. humeralis also responded to this pheromone (1.6·5.6 times increase). All species showed some cross-attraction to synthetic pheromones of three North American Carpophilus spp. The potential for using synthetic pheromones in the management of nitidulid beetles in stone fruit orchards is discussed. Introduction Nitidulid beetles (primarily Carpophi/us spp.), are worldwide pests of a variety of fruits and grains before and after harvest (Hinton 1945). In southern Australia these beetles are serious pests of ripening stone fruit (Gaven 1964; Hely et al. 1982). Fruit loss is caused primarily by adult beetles penetrating ripening fruit causing rapid breakdown. Beetles can enter fruit by chewing through the skin mostly around the stem end or in sutures. However, they often enter at sites of mechanical damage. The beetles also serve as mechanical carriers of brown rot disease (Kable 1969). The importance of Carpophilus spp. in stone fruit production has increased in recent years, following a decline in insecticide use for the control of key pests such as oriental fruit moth, Cydia molesta Busck. The development and widespread utilisation of a management strategy for C. molesta based on pheromonal disruption of mating (Vickers et al. 1985) has made stone fruit production in some areas of southern Australia largely insecticide free. Control of Carpophilus spp. in stone fruit is currently based on the use of broad spectrum insecticides applied near to harvest. This control is often unsatisfactory and can result in insecticide residues on fruit at harvest. In addition, the use of broad spectrum materials can precipitate outbreaks of pests such as mites. Management of Carpophi/us spp. using effective, non-disruptive techniques is essential to preserve stability of stone fruit ecosystems and associated integrated and biological control systems (e.g. James 1990). Volatiles from fermenting fruit attract Carpophi/us spp. (Warner 1961; Obenauf et al. 1976; Smilanick et al. 1978) and field traps based on natural or synthetic baits have been used to monitor populations. Fermented baits were used successfully to control Carpophi/us hemipterus (L.) when the insects collected by the traps were not immediately killed (Warner 1960, 1961). However, poisoned fermenting baits were not able to out-compete naturally ripe figs in orchards (Smilanick 1979), suggesting that a combination of the beetle's pheromone and host volatiles is necessary to equal the attraction of natural host materials with insects present. Bartelt et al. (l992a) reported the first example of an aggregation pheromone from nitidulids (c. hemipterus) which synergised with host volatiles. In field tests Bartelt et al. (l992b) demonstrated that combinations of the synthetic aggregation pheromone of C. hemipterus and host related attractants were consistently more effective in trapping beetles than either type of bait alone. Lin et al. (1992) reported the same phenomenon for Carpophi/us lugubris Murray using either synthetic or natural food odours in combination with synthetic pheromone. In addition to C. hemipterus and C. lugubris. male-produced aggregation pheromones have been described and synthesised for 340 D. G. JAMES ET AL. Carpophilus freemani Dobson (Bartelt et al. 1990b), Carpophilus obsoletus Erichson and Carpophilus mutilatus Erichson (Bartelt et al. 1993). The aim of the present study was to determine the response of Australian Carpophilus spp. to synthetic pheromones and host-related volatile baits. Results are presented from a 3-month study conducted in an apricot orchard near Leeton in ·southern New South Wales. Materials and methods Earlier observations in the Murrumbidgee Irrigation Area of southern New South Wales suggested e. hemiplerus was the dominant Carpophilus species arrecting ripening SlOne fruit (James unpubl. obs). Consequently, the synthetic aggregation pheromone of e. hemiplerus was the main pheromone used in this study. Occasional use was made of the synthetic pheromones of e. mUliialus, e. freemani. e. lugubris and e. obsolelus. Pheromones The following synthetic pheromone compounds were used: (2E.4E,6E.8E)-3.5.7 trimethYI-2,4,6.8-decatetraene (I); (2E,4E,6E,8E)-3,5,7-trimethyl-2.4.6.8-undecatetraene (2): (2E,4E,6E,8£)-7-ethyl-3,5-dimethyl-2,4,6,8.-decatetraene (3); (2E,4E,6E.8£)-7-ethyl-3 ,5-dimethyl 2,4,6,8-undecatetraene (4); (2E,4E,6£)-5-ethyl-3-methyl-2,4,6-nonatriene (5); (3E.5E,7£)-6-ethyl-4 methyl-3,5,7-decatriene (6); and (3E,5E,7£)-5- ethyl-7-methyl-3,5,7-undecatriene (7). Compounds 1-4 were prepared and purified as described by Bartelt el al. (l990b); 5-7 were made analogously. Each trap bait contained a total of 500 Ilg of synthetic pheromone, and the bait compositions were as follows: for e. hemiplerus, I, 2, 3 and 4 in the proportions by weight, 79: II:7:3. respectively; for e. mUlilalus. 6 and 7 in the proportions, 6:94; for e. Iugubris, 2 and 4 in the proportions. 10:90; and for C. freemani. 4 and 5 in the proportions, 4:%. For e. obsolelus, only 2 was used, as it was discovered empirically that e. obsolelus responded well to compound 2 in field tests, in California, USA (Bartelt, unpubl.) but the nature of the pheromone actually emitted by e. obsolelus remains unstudied. Rubber septa were prepared as field baits by applying 500 Ilg of pheromone (in about 10 ilL of hexane) and 300 ilL of methylene chloride and allowing the liquid to soak in. The septa were then aired in a fume hood for approximately 1 h, transferred to tightly covered bottles and slOred in a freezer prior to shipment to Australia. On arrival they were again slOred in a freezer. The septa were replaced fortnightly during the study. Baits and traps The co-attractant used in this study was fermenting whole wheat bread dough. This bait is an effective nitidulid attractant (Lin and Phelan 1991) and comprised a 4:1:2 mixture of whole wheat nour, sugar and water to which dried baker's yeast was added to start fermentation. Approximately 10 mL of this mixture held in a 20 mL glass tube, was used for baiting traps. Fermentation usually caused expansion to 20 mL and dough did not normally spill out of the tube. The dough baits were replaced weekly throughout the study. A wind-oriented pipe trap constructed from PVC plumbing pipe and screen wire, based on the design of Dowd el al. (1992), was used. Beetles entered the trap through a cone-shaped piece of screen and were finally trapped in a plastic 140 mL bottle attached to the bOll om of the trap. No killing agent was used and a screen partition in the trap prevented beetles from contacting the bait. The traps were suspended approximately 1.5 m above the ground from a wire attached to a tree branch. They were oriented to the wind by a fin so that the trap opening was always accessible to beetles approaching the traps from downwind. Experimental design The study was conducted in a small (50 x 50 m) apricot orchard, 10 km east of Leeton, from 26 November 1991 10 3 March 1992. The orchard was adjacent to a larger area (approximately 8 hal of stone fruit (peach, plum. nectarine). No broad-spectrum insecticides had been applied on this farm for at least 10 years. Twenty traps incorporated five replicates of four treatments (e. hemiplerus pheromone only, fermenting dough only, e. hemiplerus pheromone plus fermenting dough or no treatment) and were randomised in a 4 x 5 grid of.20 trees, spaced at 6 m intervals. During 10 December-4 February four additional traps containing dough and either e. mUliiarus, e. lugubris, e. obsolerus or e. freemani pheromone were located in a linear, four tree block, 15 m to the east of the main trapping grid. All of these traps were baited with e. murilarus pheromone and dough from 4 February to 3 March. The block was nood irrigated and fruit began ripening in mid-December. Thereafter, a small amount of fallen fruit was always present in the orchard providing a food supply for nitidulid populations. Traps were examined at weekly intervals and beetles collected and taken back to the laboratory. Nitidulids were identified to species using Dobson (1954, 1964) and reference specimens previously identified by R. M. Dobson. Data on numbers of captured beetles were subjected to analysis of variance and least significant difference procedures. Samples of 40-50 fallen fruit were collecled weekly from 29 January-3 ~Iarch and examined in the laboralory 10 provide information on the identity and abundance of adult nilidulids using Ihis resource.