A low <i>Platypus quercivorus</i> hole density does not necessarily indicate a small flying population

The ambrosia beetle Platypus quercivorus is a vector for the fungus that causes Japanese oak wilt, and susceptibility to infestation by P. quercivorus varies by tree species. We postulated that P. quercivorus discriminates among host tree species differing in susceptibility to attack. To test this postulate, we counted the number of flying male beetles (NFM), the number of holes bored by male beetles (NH), and the number of flying female beetles (NFF) per unit area of bark surface in three fagaceous tree species: Quercus crispula (with high susceptibility to infestation) and Q. serrata and Castanea crenata (both with low susceptibility). NFM and NH were used to calculate the proportion of male beetles that bored holes out of those that flew to the tree (PBM). We used generalized additive models to predict NFM, NFF, and PBM. The locations of trees, expressed as x and y coordinates, numbers of weeks after the first male beetle's flying (WEEK), diameters of trees 130 cm above ground (DBH), and tree species (SP) were incorporated into the models as candidate explanatory variables. The best-fit models for NFM and NFF included WEEK and DBH and the effect of location; SP was not included in the models. For PBM, the best-fit model included WEEK, DBH, and SP. The results indicate that male P. quercivorus prefer Q. crispula to Q. serrata and C. crenata and that selection is made before boring holes on trees, but that P. quercivorus do not discriminate among host species when they fly to trees.

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“…3). The same tendency has been reported for Q. salicina, which has lower susceptibility to P. quercivorus infestation (Yamasaki et al 2007).…”

Section: Discussionsupporting

confidence: 64%

Discrimination among host tree species by the ambrosia beetlePlatypus quercivorus

Yamasaki

Futai

2012

Journal of Forest Research

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“…For example, Q. serrata is less susceptible to the disease than is Q. crispula (Shiomi and Osaki 1997;Inoue et al 2000;Kobayashi and Hagita 2000;Kobayashi and Shibata 2001;Kobayashi and Ueda 2001), probably because of active sap exudation in Q. serrata ). In part, the lower susceptibility of Q. salicina can be explained by the low proportion of male P. quercivorus that attack and bore holes into the trees (Yamasaki et al 2007).…”

Section: Introductionmentioning

confidence: 99%

Types of frass produced by the ambrosia beetlePlatypus quercivorusduring gallery construction, and host suitability of five tree species for the beetle

Tarno

Endoh

et al. 2011

Journal of Forest Research

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We studied the biology of the ambrosia beetle Platypus quercivorus in the logs of five tree species to determine: (1) the relationship between the amount of frass produced by beetles and tunnel length, (2) the relationship between frass shape and the morphological characteristics of P. quercivorus mouthparts, and (3) the suitability of five tree species for P. quercivorus reproduction. Five logs each from healthy Quercus crispula, Q. serrata, Castanea crenata, Sorbus japonica, and Cryptomeria japonica trees were used in this experiment. The results showed that there was a linear relationship between the amount of frass and tunnel length. Whenever powdery frass was produced, larvae were found in the gallery in the log, while fibrous frass was present only in galleries that contained just adults. The mouthparts of adults were completely sclerotized, which likely accounts for the fibrous frass production. Host preference of P. quercivorus was examined at two stages using five tree species. The first stage is digging initiation, which concerns male preference for digging a tunnel. More holes were made by males on S. japonica and Q. serrata logs, while fewer holes were made on C. japonica logs. The second stage is characterized by female orientation, mating, and progeny development. Platypus quercivorus could complete its lifecycle only in the two Quercus spp.

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“…For example, Q. serrata exhibits lower susceptibility to the disease than Q. crispula (Shiomi and Osaki, 1997;Inoue et al, 2000;Kobayashi and Hagita, 2000;Kobayashi and Shibata, 2001; Kobayashi and Ueda, 2001), probably because of active sap exudation in Q. serrata (Kobayashi et al, 2004). The low susceptibility of Q. salicina can be explained in part by the low proportion of male P. quercivorus that bored holes in trees after flying to them (Yamasaki et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Host selection by Platypus quercivorus (Murayama) (Coleoptera: Platypodidae) before and after flying to trees

Yamasaki

Futai

2008

Appl. Entomol. Zool.

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The ambrosia beetle Platypus quercivorus causes mass mortality of fagaceous trees throughout Japan. Previous studies demonstrated low levels of P. quercivorus attack on both thinner trees and re-attacked trees with previous infection history. To determine the causes of the low levels of attack on these trees, the patterns of attack by P. quercivorus were investigated in 35 Quercus crispula trees for two consecutive years. Logistic regression analysis indicated a significant positive effect of tree size on the probability of male beetle flying to trees, although previous infection history was not selected as an explanatory variable in the model. Tree size and previous infection history exhibited significant positive and negative effects, respectively, when both were selected as explanatory variables in a model predicting the probability of male beetle boring holes in trees. These results suggest that P. quercivorus disregards thinner trees, and flies away from trees with previous infection history after approaching.

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A low Platypus quercivorus hole density does not necessarily indicate a small flying population

Cited by 6 publications

References 7 publications

Discrimination among host tree species by the ambrosia beetlePlatypus quercivorus

Discrimination among host tree species by the ambrosia beetlePlatypus quercivorus

Types of frass produced by the ambrosia beetlePlatypus quercivorusduring gallery construction, and host suitability of five tree species for the beetle

Host selection by Platypus quercivorus (Murayama) (Coleoptera: Platypodidae) before and after flying to trees

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