京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第19534号 / 理博第4194号 / 新制||理||1602(附属図書館) / 32570 / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 髙林 純示, 教授 永益 英敏, 教授 石田 厚 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・論文博士 / 博士(農学) / 乙第13034号 / 論農博第2835号 / 新制||農||1044(附属図書館) / 学位論文||H28||N5007(農学部図書室) / 32992 / 京都大学大学院農学研究科農学専攻 / (主査)教授 坪山 直生, 教授 黒木 裕士, 教授 妻木 範行 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Among several early-season insect pests threatening apple production in eastern North America, plum curculio (PC), Conotrachelus nenuphar Herbst (Coleoptera: Curculionidae), is one of the most devastating pests of pome and stone fruits. Historically, several methods have been used to monitor and control plum curculio in apple orchards. The odor-baited trap tree approach has proven to serve as an effective monitoring and attract-and-kill system for plum curculio. The synergistic lure consisting of benzaldehyde (a plant volatile) and grandisoic acid (the PC aggregation pheromone) is used in this approach. However, the high cost of the lure and the degradation of benzaldehyde by UV light and heat have resulted in limited grower adoption. The major goals of this study were (1) to evaluate under field conditions, the attractiveness of methyl salicylate (MES) to PC, and to determine if it can replace the benzaldehyde (BEN), and (2) to test whether we can manipulate insect pest behavior through host plant preference by grafting selected perimeter- row trees with multiple cultivars. My results indicated that (1) methyl salicylate in combination with grandisoic acid was as attractive to PC as the standard synergistic lure composed of benzaldehyde and grandisoic acid, therefore MES can be used as a replacement for BEN, (2) trees grafted with six cultivars were more attractive to PC and concentrated more PC fruit injuries, compared to non-grafted trees, and (3) ‘Wickson’ and ‘Red Astrachan’ received numerically more PC injuries while ‘Dabinett’ received the lowest level of injury compared with other cultivars. These results highlight that a semiochemical-based strategy is a low-cost and grower-friendly approach to monitoring and controlling the PC population.

Harlequin bug (HB), Murgantia histrionica (Hahn), is a pest of cole crops. Alternative control strategies were investigated for control of HB, including trap cropping and systemic neonicotinoid insecticide applications. Potential trap crops, mustard (Brassica juncea "Southern Giant Curled" ), rapeseed (B. napus "Athena"), rapini (B. rapa) and arugula (Eruca sativa) were preferred over collard (B. oleracea "Champion"), and a non-brassica control, bean (Phaseolus vulgaris "Bronco") in field-cage choice tests. Harlequin bug could not complete development on bean, developed poorly on arugula but was found to complete development on mustard, collard, rapeseed and rapini. In the field, mustard was found to be an effective trap crop for reducing HB feeding injury on collard at three experimental sites in 2010 and 2011. Augmentation of the mustard trap crop with a systemic, neonicotinoid insecticide did not increase the level of control of harlequin bug for the duration of the ten week growing period. In olfactometer choice tests, male HB responded to plant volatiles of bean, collard and mustard, but preferred Brassica volatiles over those from bean. Female response to plant volatiles alone was weak and inconsistent. Both males and females preferred volatiles from other males feeding on Brassica host plant over plant volatiles alone, and were deterred by volatiles from males feeding on bean versus the plant alone. Laboratory toxicity assays revealed that the neonicotinoid insecticides imidacloprid, thiamethoxam, dinotefuran, and clothianidin were toxic to HB nymphs; LC50 = 0.57, 0.52, 0.39, and 0.39 mg ai/liter, respectively. Field experiments were conducted to evaluate the efficacy of these insecticides over time when applied as a one-time drench, and all were found to provide significantly higher mortality of HB for at least 14 days after application. / Ph. D.

Experiments were conducted to assess whether a concept termed 'attract and reward' (A&R) could enhance conservation biological control (CBC). In A&R, a synthetically-produced herbivore induced plant volatile (HIPV) ('attract') is combined with a floral resource ('reward'). It is anticipated that the two will work synergistically attracting natural enemies into the crop ('attract') and maintaining them within the crop ('reward'). The study system consists of brassica, the most commonly occurring brassica herbivores, their natural enemies and higher order natural enemies. The HIPV deployed is methyl salicylate (MeSA) and the floral resource is buckwheat Fagopyrum esculentum. The aim of the first two field experiments, in 2007 and 2008, was to evaluate the effects of MeSA and MeSA combined with buckwheat (A&R) on the abundance of arthropods from three trophic levels. In 2007, a field experiment was conducted using MeSA alone. The mean abundance of the leafmining fly Scaptomyza flava (trophic level 2), the diamondback moth (trophic level 2)(DBM) parasitoid Diadegma semiclausum (trophic level 2) and the hoverfly Melangyna novaezealandiae (trophic level 3) was increased in MeSA-treatments by up to 300% and for the brown lacewing parasitoid Anacharis zealandica a maximum mean increase of 600% was recorded. Significantly more females of the D. semiclausum and M. novaezealandiae were attracted to MeSA than males. When A&R was deployed in 2008, were arthropods from the third and fourth trophic levels affected. For none of the species was there a synergistic effect between 'attract' and 'reward' on their abundance. The brown lacewing Micromus tasmaniae (trophic level 3), two parasitoids of DBM and one of cabbage white butterfly Pieris rapae (trophic level 2) increased significantly in treatments with buckwheat. The hoverfly Melanostoma fasciatum (trophic level 3) was significantly more abundant in treatments with MeSA, but significantly less abundant in treatments with buckwheat. The effect of MeSA on the fourth trophic level parasitoid Anacharis zealandica (trophic level 4) was inconsistent between years. Here it significantly decreased its abundance, while treatments with buckwheat increased it. Significantly fewer male than female D. semiclausum were attracted to MeSA only treatments. These experiments show that MeSA and buckwheat can have unwanted effects on arthropod abundance which may disrupt CBC. To assess the effect of A&R on CBC a further field experiment evaluating herbivore densities, predation, parasitism and hyper-parasitism rates was conducted. The only effect was significantly higher aphid parasitism in treatments with MeSA. Based on the results from the field experiments it remained unclear whether it was MeSA or a blend of volatiles produced by MeSA-induced host plants that were attractive to the arthropods. An olfactory experiment was conducted to evaluate if the aphid parasitoid Aphidius colemani can be attracted to two different concentrations of MeSA diluted in Synertrol oil. Significantly more parasitoids were attracted to 2.0% MeSA than to air while the parasitoid did not respond to the 0.5% concentration. These results indicate that A&R has potential as a CBC technique, as long as any unwanted side effects can be managed. Although there were no synergistic effects between 'attract' and 'reward' on the abundance of individual natural enemies, combining MeSA and buckwheat could still be beneficial because the two techniques increase the abundance of different natural enemies.

Experiments were conducted to assess whether a concept termed 'attract and reward' (A&R) could enhance conservation biological control (CBC). In A&R, a synthetically-produced herbivore induced plant volatile (HIPV) ('attract') is combined with a floral resource ('reward'). It is anticipated that the two will work synergistically attracting natural enemies into the crop ('attract') and maintaining them within the crop ('reward'). The study system consists of brassica, the most commonly occurring brassica herbivores, their natural enemies and higher order natural enemies. The HIPV deployed is methyl salicylate (MeSA) and the floral resource is buckwheat Fagopyrum esculentum. The aim of the first two field experiments, in 2007 and 2008, was to evaluate the effects of MeSA and MeSA combined with buckwheat (A&R) on the abundance of arthropods from three trophic levels. In 2007, a field experiment was conducted using MeSA alone. The mean abundance of the leafmining fly Scaptomyza flava (trophic level 2), the diamondback moth (trophic level 2)(DBM) parasitoid Diadegma semiclausum (trophic level 2) and the hoverfly Melangyna novaezealandiae (trophic level 3) was increased in MeSA-treatments by up to 300% and for the brown lacewing parasitoid Anacharis zealandica a maximum mean increase of 600% was recorded. Significantly more females of the D. semiclausum and M. novaezealandiae were attracted to MeSA than males. When A&R was deployed in 2008, were arthropods from the third and fourth trophic levels affected. For none of the species was there a synergistic effect between 'attract' and 'reward' on their abundance. The brown lacewing Micromus tasmaniae (trophic level 3), two parasitoids of DBM and one of cabbage white butterfly Pieris rapae (trophic level 2) increased significantly in treatments with buckwheat. The hoverfly Melanostoma fasciatum (trophic level 3) was significantly more abundant in treatments with MeSA, but significantly less abundant in treatments with buckwheat. The effect of MeSA on the fourth trophic level parasitoid Anacharis zealandica (trophic level 4) was inconsistent between years. Here it significantly decreased its abundance, while treatments with buckwheat increased it. Significantly fewer male than female D. semiclausum were attracted to MeSA only treatments. These experiments show that MeSA and buckwheat can have unwanted effects on arthropod abundance which may disrupt CBC. To assess the effect of A&R on CBC a further field experiment evaluating herbivore densities, predation, parasitism and hyper-parasitism rates was conducted. The only effect was significantly higher aphid parasitism in treatments with MeSA. Based on the results from the field experiments it remained unclear whether it was MeSA or a blend of volatiles produced by MeSA-induced host plants that were attractive to the arthropods. An olfactory experiment was conducted to evaluate if the aphid parasitoid Aphidius colemani can be attracted to two different concentrations of MeSA diluted in Synertrol oil. Significantly more parasitoids were attracted to 2.0% MeSA than to air while the parasitoid did not respond to the 0.5% concentration. These results indicate that A&R has potential as a CBC technique, as long as any unwanted side effects can be managed. Although there were no synergistic effects between 'attract' and 'reward' on the abundance of individual natural enemies, combining MeSA and buckwheat could still be beneficial because the two techniques increase the abundance of different natural enemies.