Vision Fixation of Flightless Monophagous Leaf Beetle Ambrostoma quadriimpressum in Relation to Host Location
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ORIGINAL ARTICLE
Vision Fixation of Flightless Monophagous Leaf Beetle Ambrostoma quadriimpressum in Relation to Host Location Fan Sun
&
Tianzhong Jing & Chao Bao & Jihua Hu
Received: 17 April 2019 / Revised: 31 July 2020 / Accepted: 20 August 2020 # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract The leaf beetle Ambrostoma quadriimpressum (Coleoptera: Chrysomelidae) is monophagous on elm trees, Ulmus pumila (Ulmaceae). As this species lives on elm during most of its life but pupates and overwinters as an adult in the soil, the flightless beetle seeks a host plant after emergence from the soil. Previous field experiments showed that the beetle locates host plants via orientation to standing black targets and does not recognize host plant prior to contact it. In order to establish the relationship between preferential vision fixation and host locating behavior, we investigated the visual orientation by placing individuals in the center of an arena and recording their responses to different targets at the perimeter. Responses were compared for a control object - a vertically positioned 10 × 30 cm black rectangle - versus a treatment object that differed from the control in terms of width, height, orientation, edge features, or color. Higher, wider, vertical, and solid black objects were more attractive to the beetle than objects that are shorter, thinner, inclined or have stripes, whereas two altering features (wavy or serrated) of the target’s vertical edge had no effect. The red and black targets were equally attractive, whereas blue, green or yellow objects were less attractive F. Sun (*) : T. Jing : C. Bao School of Forestry, Northeast Forestry University, Harbin 150040, China e-mail: [email protected] J. Hu Institute of Microbiology, Heilongjiang Academy of Sciences, Harbin 150010, China
than black ones, and adding a green disk at the top of a black target did no enhance attraction. These visual preferences corroborate that the beetle is attracted to objects that resemble a tree trunk during the field search for a host. The implicated mechanism of vision fixation and host locating pattern of this beetle are discussed. Keywords Visual orientation . black target . choice experiments . host-plant finding . monophagous
Introduction Phytophagous insects find their host by orientation to stimulus sources, in which both odors and visual features of host appear to provide important directionality cues (Prokopy and Owens 1983; Schoonhoven et al. 2005). However, in many specialized herbivores no evident orientation can be demonstrated when they are at some distance from their host plant, and it appears that many insects do not discriminate between plant species prior to physical contact. For example, the Colorado potato beetle, Leptinotarsa decemlineata, can perceive and orient to odors of its host in laboratory studies (Visser 1979; Thiery and Visser 1986). Jermy et al. (1988), however, found that beetles released at the center of a 60 cm diameter arena with hosts and non-hosts placed
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