Thermoregulatory Behavior and Fungal Infection ofAnoplophora glabripennis(Coleoptera: Cerambycidae)

Abstract

Asian longhorned beetles, Anoplophora glabripennis (Motschulsky), are invasive wood borers that are native to China and Korea but have been introduced to North America and Europe. These beetles have great potential to negatively impact economic and environmental interests in hardwood and urban forests if they become established. The entomopathogenic fungus Metarhizium brunneum Petch (previously Metarhizium anisopliae (Metschnikoff) Sorokin) is under development for control of A. glabripennis. Some insect species eliminate pathogens or delay disease progression through thermoregulation. Because Asian longhorned beetles had been observed occupying sunlit areas of the tree canopy, we hypothesized that behavioral fevering could be used to delay mortality of fungal-infected beetles. M. brunneum cultures incubated at 34°C for 5 h/d grew significantly slower compared with cultures incubated at lower temperatures. Holding M. brunneum-infected A. glabripennis at 34°C for 5 h/d significantly delayed mortality by 2 d compared with infected beetles held at ≤31°C. Adult A. glabripennis did not exhibit behavioral fever when infected. Uninfected males, when provided with food, and both uninfected males and females when deprived of food, slightly increased their preferred temperature over time. When held at 15°C before being placed into temperature gradients, uninfected beetles did not increase their temperatures above ambient. Results demonstrate that M. brunneum-infected A. glabripennis do not exhibit behaviors necessary to elevate their body temperatures enough to combat M. brunneum infections through thermoregulation.

Fungal infection dynamics in response to temperature in the lepidopteran insect Galleria mellonella

“…Some insects seek lower temperature environments that presumably slow down fungal development, giving the insect more time to mount an effective defense response to resist the pathogen (Hunt et al ., ). Quite a few insects do not regulate temperature but their survival is vastly improved if kept at higher temperatures, as reported for the Asian longhorned beetle, Anoplophora glabripennis (Motschulsky) exposed to Metarhizium brunneum (Fisher & Hajek, ).…”

Microbial Control of Invasive Forest Pests with Entomopathogenic Fungi: A Review of the Current Situation

“…Furthermore, it appeared that mature and old females of A. glabripennis were more susceptible to M. brunneum than males of equal ages, and more females had detectable fungal blastospores in their hemolymph compared to mature and old males [135]. Also, laboratory conditions demonstrated that M. brunneum -infected A. glabripennis does not exhibit behavioral fever (elevating body temperature by exposing to a heat source to ward off fungal infections [136]. Bioassays conducted in the United States showed that the Japanese commercial strain of B. asiatica and the commercial strain F52 of M. brunneum were more virulent than two North American B. brongniartii isolates against A. glabripennis [137].…”

Light in the box—photobiological examination chamber with light trap ventilation system for studying fungal surface cultures illustrated with Metarhizium brunneum and Beauveria brongniartii

“…For example, the choice of luminant (i.e. bulb versus LED) can make a considerable difference in heat development during the experiment, which can become problematic if not compensated, since some fungi such as Metarhizium brunneum are considerably temperature sensitive [ 36 ]. Unwanted light impulses even in the range of seconds (e.g., by opening the lid of an incubator system within a room without controlled light conditions) can already alter fungal metabolism [ 25 , 30 , 37 ] and thus distort the observed photo response.…”