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Iwatani Y.,Hirosaki University | Tsurui K.,University of Ryukyus | Honma A.,Okinawa Prefectural Plant Protection Center
2016 IEEE International Conference on Robotics and Biomimetics, ROBIO 2016 | Year: 2016

The wolf spider is an important predator of some agricultural pests. The final objective in this research is to characterize hunting locomotion of the spider and to design a hunting robot that mimics the spider's hunting locomotion. To this end, this paper proposes an image processing procedure to estimate the two-dimensional position and direction of a wolf spider in an observation box from video images. A spider is first extracted from each captured image by background subtraction and extraction of the largest connected component. The extracted spider image is divided into the body part and the leg part in order to estimate the position and the direction in the following steps. The position of the spider is determined as the center of the body part. The direction of the spider is estimated by a combination of an initialization operation and a sequential computation. The initialization is executed by using image moments and the difference between the centers of the body part and the leg part. The sequential computation is performed by using directions at the previous or subsequent time step. The proposed estimation procedure is applied to three wolf spider individuals. This paper demonstrates that the proposed estimation procedure is valid for the three individuals and it is unaffected by sexual differences or differences in leg arrangements. The proposed estimation procedure is available for locomotion analysis of spiders. © 2016 IEEE.


Kuriwada T.,Japan National Agriculture and Food Research Organization | Kumano N.,Okinawa Prefectural Plant Protection Center | Shiromoto K.,Okinawa Prefectural Plant Protection Center | Haraguchi D.,Okinawa Prefectural Agricultural Research Center
Journal of Applied Entomology | Year: 2014

For ensuring the effectiveness of sterile insect technique (SIT) programmes, maintaining the reproductive competitiveness and dispersal ability of mass-reared sterile males is essential. Inadvertent selection is an important genetic process that frequently occurs during mass rearing to produce sterile males. We investigated the effect of mass-rearing conditions on the responsiveness to sex pheromones and spontaneous flight activity of males of the sweetpotato weevil Cylas formicarius (Coleoptera: Brentidae). There were no significant differences in the responsiveness to sex pheromones and spontaneous flight activity between wild and mass-reared strains. These results indicate that mass-reared strains of C. formicarius might not cause serious problems for implementing SIT programmes. © 2013 Blackwell Verlag GmbH.


Kumano N.,Okinawa Prefectural Plant Protection Center | Kuriwada T.,Okinawa Prefectural Plant Protection Center | Shiromoto K.,Okinawa Prefectural Plant Protection Center | Haraguchi D.,Okinawa Prefectural Plant Protection Center | Kohama T.,Okinawa Prefectural Agricultural Research Center
Agricultural and Forest Entomology | Year: 2011

1 The sterile insect technique (SIT) is widely used to suppress or eradicate target pest insect populations. 2 The effectiveness of SIT depends on the ability of released sterile males to mate with and inseminate wild females. The use of gamma radiation to induce sterility, however, negatively affects both somatic cells as well as reproductive cells. Consequently, mating performance of sterilized individuals decreases drastically over time. The mating propensity of sterilized Euscepes postfasciatus (Fairmaire) males irradiated with a single dose of 150 Gy (the current standard of the Okinawa Prefecture SIT programme) is equal to that of non-irradiated weevils for the first 6 days. 3 Fractionated irradiation, in which a sterilizing dose is delivered over time in a series of smaller irradiations, reduces the damage of irradiation in insects. In the present study, we evaluated the effect of fractionated irradiation on male fertilization ability, longevity and mating propensity of E. postfasciatus for a period of 16 days after irradiation. 4 Although fractionated irradiation totalling 150 Gy was found to induce full sterility regardless of the number of individual doses, the mating propensity of male weevils sterilized by fractionated irradiation was maintained for the first 12 days. These results demonstrate that fractionated irradiation can be highly advantageous in programmes aimed at eradication of E. postfasciatus. © 2011 The Authors. Agricultural and Forest Entomology © 2011 The Royal Entomological Society.


Kijima K.,Okinawa Prefectural Agricultural Research Center | Kijima K.,Okinawa Prefectural Plant Protection Center | Tarora K.,Okinawa Prefectural Agricultural Research Center
Japanese Journal of Applied Entomology and Zoology | Year: 2010

White grub Dasylepida ishigakiensis (Coleoptera: Scarabaeidae) is an important pest that infests the roots and underground stems of sugarcane. Thus, the establishment of an effective control method for this pest is urgently required. Changes in the vertical distribution of third stadium larvae of D. ishigakiensis in the soil were surveyed in a post-harvest sugarcane field on Miyako Island, Okinawa, in 2005. Although 73.8% of third stadium larvae were captured within 30 cm soil depth on March 17, the rate decreased to 38.1% on April 5 and to 25.0% on April 17, suggesting that most larvae move to deeper soil from the end of March to mid-April. The possibility of physical control by rotary tillage while the larvae are in shallow soil (0 to 30 cm) was examined in another field on March 16, 2005, with three treatments: 1) control, 2) tilling once and 3) tilling twice. The number of living larvae per sugarcane stool with tilling once or twice was much lower than in the control. Furthermore, the difference between the control and tilling twice six days after treatment was significant. These results indicate that tilling sugarcane fields by mid-March after the harvest can effectively control D. ishigakiensis larvae.


Tanaka H.,University of Ryukyus | Uesato T.,Okinawa Prefectural Plant Protection Center
Applied Entomology and Zoology | Year: 2012

Four species of mealybugs, Dysmicoccus neobrevipes, Phenacoccus defectus, Ph. parvus, and Ph. solenopsis (Hemiptera: Coccoidea: Pseudococcidae) are recorded for the first time from Japan in the Ryûkyû (Ryukyu) Archipelago, with brief biological notes. We discuss some features of these species compared with those of related species, D. brevipes and Ph. solani, and we consider their potential risks to Japanese agriculture and/or horticulture. © 2012 The Japanese Society of Applied Entomology and Zoology.


Kuriwada T.,Kyushu University | Kuriwada T.,Okinawa Prefectural Plant Protection Center | Kasuya E.,Kyushu University
Journal of Ethology | Year: 2011

We investigated how male age and body weight influence male mating effort in the bell cricket Meloimorpha japonica. We adopted a longitudinal approach to study resource allocation to male mating effort (calling duration during 24 h) in the bell cricket. Calling durations and body weight of each male were measured at 7-8 days (young age), 14-15 days (middle age), and 22-25 days (old age) after the final molt. Calling duration increased between young and middle age. During the period between middle and old age, the amount of change in the calling duration was positively correlated with the body weight. The results suggested that older (i. e., low residual reproductive value) and better quality males invested more resources in mating effort. © 2010 Japan Ethological Society and Springer.


Kuriwada T.,Okinawa Prefectural Plant Protection Center | Hosokawa T.,Japan National Institute of Advanced Industrial Science and Technology | Kumano N.,Okinawa Prefectural Plant Protection Center | Shiromoto K.,Okinawa Prefectural Plant Protection Center | And 2 more authors.
PLoS ONE | Year: 2010

Weevils constitute the most species-rich animal group with over 60,000 described species, many of which possess specialized symbiotic organs and harbor bacterial endosymbionts. Among the diverse microbial associates of weevils, Nardonella spp. represent the most ancient and widespread endosymbiont lineage, having co-speciated with the host weevils for over 125 million years. Thus far, however, no empirical work on the role of Nardonella for weevil biology has been reported. Here we investigated the biological role of the Nardonella endosymbiont for the West Indian sweet potato weevil, Euscepes postfasciatus. This insect is an experimentally tractable pest insect that can easily be reared on a natural diet of sweet potato root as well as on an agar-based artificial diet. By larval feeding on an antibiotic-containing artificial diet, Nardonella infection was effectively eliminated from the treated insects. The antibiotic-treated insects exhibited significantly lighter body weight and lower growth rate than the control insects. Then, the antibiotic-treated insects and the control insects were respectively allowed to mate and oviposit on fresh sweet potatoes without the antibiotic. The offspring of the antibiotic-treated insects, which were all Nardonella-negative, exhibited significantly lighter body weight, smaller body size, lower growth rate and paler body color in comparison with the offspring of the control insects, which were all Nardonellapositive. In conclusion, the Nardonella endosymbiont is involved in normal growth and development of the host weevil. The biological role of the endosymbiont probably underlies the long-lasting host-symbiont co-speciation in the evolutionary course of weevils. © 2010 Kuriwada et al.


Kuriwada T.,Okinawa Prefectural Plant Protection Center | Kumano N.,Okinawa Prefectural Plant Protection Center | Shiromoto K.,Okinawa Prefectural Plant Protection Center | Haraguchi D.,Okinawa Prefectural Plant Protection Center
Ethology | Year: 2011

When there is an inbreeding depression, mating with a kin individual is generally considered maladaptive behaviour. However, in some conditions, the inclusive fitness benefits from inbreeding may outweigh the costs of inbreeding depression, and thus, inbreeding tolerance is often adaptive. Inbreeding depression and the effect of relatedness on mating behaviour in the West Indian sweet potato weevil Euscepes postfasciatus were examined. No significant inbreeding depression was detected as indicated by body weight and number of progeny emerging from sweet potato roots. Male mating performance (i.e. number of mating occurrences per night) was adversely affected by inbreeding depression, but the effect was low (fitness loss was 6.3%). Although there were no significant differences in latency to mounting, pre-copulatory guarding, copulation and post-copulatory guarding duration between full-sib and non-kin pairs, the copulation rate of full-sib pairs was significantly higher than that of non-kin pairs. These results support the theoretical prediction that when inbreeding depression is weak, copulation with close relative individuals is favoured. © 2011 Blackwell Verlag GmbH.


Kuriwada T.,Okinawa Prefectural Plant Protection Center | Kuriwada T.,Ryukyu Sankei Co. | Kumano N.,Okinawa Prefectural Plant Protection Center | Kumano N.,Ryukyu Sankei Co. | And 3 more authors.
Behavioral Ecology and Sociobiology | Year: 2011

Inadvertent selection is an important genetic process that frequently occurs during laboratory culture. The mass-reared strain of the sweet potato weevil Cylas formicarius exhibits stronger inbreeding depression than the wild strain does. When inbreeding depression occurs in a population, mating with a close relative is often considered maladaptive; however, in some contexts, the inclusive fitness benefits of inbreeding may outweigh the costs, favoring individuals that tolerate a low level of inbreeding depression. Theory predicts that mass-reared strain weevils will avoid inbreeding while wild strain weevils will tolerate inbreeding. To examine this prediction, we compared the effect of relatedness on the mating and insemination successes in mass-reared and wild strains of C. formicarius. While close relative pairs of the wild strain copulated less frequently than non-kin pairs, almost all mass-reared strain pairs copulated irrespective of relatedness. The results showed that the strain with weak inbreeding depression (wild strain) avoided inbreeding, whereas the strain with strong inbreeding depression (mass-reared strain) tolerated inbreeding. The contradiction between the theoretical prediction and our results is discussed from the perspective of laboratory adaptation, mating systems, and life history of C. formicarius. © 2011 Springer-Verlag.


Kuriwada T.,Okinawa Prefectural Plant Protection Center | Kumano N.,Okinawa Prefectural Plant Protection Center | Shiromoto K.,Okinawa Prefectural Plant Protection Center | Haraguchi D.,Okinawa Prefectural Plant Protection Center
Physiological Entomology | Year: 2011

Because life-history theory predicts that risky behaviours such as mating should increase as life expectancy decreases, predatory avoidance is expected to decrease with age. However, this prediction has not been examined. In the present study, the effect of age on death-feigning behaviour, a form of predatory avoidance behaviour in the sweetpotato weevil Cylas formicarius (Summers) (Coleoptera: Brentidae), is investigated by performing a longitudinal study. Because the effects of mating history and age usually cannot be distinguished, mating history is controlled. The results show that only female weevils decrease the investment in death-feigning behaviour with age, whereas male weevils do not show any age-related change. In addition, death-feigning behaviour of mated females is longer than that of virgin females, possibly because additional mating partners would be not needed by mated females. © 2011 The Authors. Physiological Entomology © 2011 The Royal Entomological Society.

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