Thermal Behavior of Two Acridid Species: Effects of Habitat and Season on Body Temperature and the Potential Impact on Biocontrol with Pathogens

Abstract

Thermoregulatory behavior was studied in two key acridid pest species from west and south Africa. Locustana pardalina Walker (Orthoptera: Acrididae) from the arid Karoo region of South Africa was an active behavioral thermoregulator using postural adjustments and microhabitat selection to elevate and then maintain body temperatures at a preferred level between 38 and 41ЊC for much of the day. Both cool weather and time of season signiÞcantly affected the ability of these locusts to reach and maintain these preferred temperatures. Hieroglyphus daganensis Krauss (Orthoptera: Acrididae) from the humid tropical river valleys of west Africa was not an active behavioral thermoregulator and showed none of the postures or habitat selection associated with such behavior. Body temperatures varied little across the day being generally around 32ЊC. The humid, wet habitat where this species occurs and the uniformity of the thermal environment appeared to preclude the development of elaborate thermal behaviors seen in L. pardalina and other behaviorally thermoregulating ectotherms. The implications of host thermal behavior and the marked difference both within and between species under different environmental conditions are discussed in terms of biological control using a biopesticide based on an entomopathogenic fungus. It is concluded that the fundamental importance of host body temperature in relation to the Þtness of the insect and its ability to cope with disease challenge, although generally overlooked in biocontrol programs, has signiÞcant implications for the successful development of microbial pest control.

Biotic Potential of a Short-Horned Grasshopper, Oxya hyla hyla Serville (Orthoptera: Acrididae) to Assess Its Biomass Producing Capacity

“…Hinks and Erlandson (1994) opined that temperature is a very important and determining factor for grasshopper rearing. Moreover, it has been reported that reproductive potential in grasshopper is highly temperature dependant (Whitman 1998;Blanford and Thomas 2000). Das et al (2012) insects produce a biomass of 18.48 ± 1.67 g wet weight in one generation.…”

Coping with crowds: Density-dependent disease resistance in desert locusts

“…Resistance of locusts and grasshoppers to disease is strongly affected by temperature and the thermoregulatory behavior of the infected host (27)(28)(29)(30). Studies have shown that gregaria desert locusts enhance their resistance to M. anisopliae var.…”

Eicosanoid involvement in the regulation of behavioral fever in the desert locust, Schistocerca gregaria

“…Many acridids, particularly those that live in seasonally constrained environments (Whitman, 1988), or environments that have large diurnal fluctuations in temperature (Blanford and Thomas, 2000), use basking and/or selection of thermal microenvironment, to gain a measure of control over body temperature. It is thought that these behaviorally thermoregulating acridids have a preferred, Archives of Insect Biochemistry and Physiology or "set point," body temperature that they aim to maintain for as long as possible given suitable environmental conditions.…”