Temperature sensitivity of the pyloric neuromuscular system and its modulation by dopamine

We report here the effects of temperature on the p1 neuromuscular system of the stomatogastric system of the lobster (Panulirus interruptus). Muscle force generation, in response to both the spontaneously rhythmic in vitro pyloric network neural activity and direct, controlled motor nerve stimulation, dramatically decreased as temperature increased, sufficiently that stomach movements would very unlikely be maintained at warm temperatures. However, animals fed in warm tanks showed statistically identical food digestion to those in cold tanks. Applying dopamine, a circulating hormone in crustacea, increased muscle force production at all temperatures and abolished neuromuscular system temperature dependence. Modulation may thus exist not only to increase the diversity of produced behaviors, but also to maintain individual behaviors when environmental conditions (such as temperature) vary

Sequestered Alkaloid Defenses in the Dendrobatid Poison Frog Oophaga pumilio Provide Variable Protection from Microbial Pathogens

Most amphibians produce their own defensive chemicals; however, poison frogs sequester their alkaloid-based defenses from dietary arthropods. Alkaloids function as a defense against predators, and certain types appear to inhibit microbial growth. Alkaloid defenses vary considerably among populations of poison frogs, reflecting geographic differences in availability of dietary arthropods. Consequently, environmentally driven differences in frog defenses may have significant implications regarding their protection against pathogens. While natural alkaloid mixtures in dendrobatid poison frogs have recently been shown to inhibit growth of non-pathogenic microbes, no studies have examined the effectiveness of alkaloids against microbes that infect these frogs. Herein, we examined how alkaloid defenses in the dendrobatid poison frog, Oophaga pumilio, affect growth of the known anuran pathogens Aeromonas hydrophila and Klebsiella pneumoniae. Frogs were collected from five locations throughout Costa Rica that are known to vary in their alkaloid profiles. Alkaloids were isolated from individual skins, and extracts were assayed against both pathogens. Microbe subcultures were inoculated with extracted alkaloids to create dose-response curves. Subsequent spectrophotometry and cell counting assays were used to assess growth inhibition. GC-MS was used to characterize and quantify alkaloids in frog extracts, and our results suggest that variation in alkaloid defenses lead to differences in inhibition of these pathogens. The present study provides the first evidence that alkaloid variation in a dendrobatid poison frog is associated with differences in inhibition of anuran pathogens, and offers further support that alkaloid defenses in poison frogs confer protection against both pathogens and predators

The invasive kudzu bug, Megacopta cribraria (Hemiptera: Plataspidae) as an agricultural and nuisance pest

The invasive “kudzu bug,” Megacopta cribraria (Hemiptera: Plataspidae) is a native of Asia that was found in northeastern Georgia in fall 2009. This insect has since spread rapidly throughout the southeastern U.S., and is abundant in much of South Carolina. Megacopta cribraria feed on the vascular fluid of several legumes, primarily kudzu, Puereria montana var. lobata, and soybeans, Glycine max. These insects enter soybean fields in often alarming numbers, leaving conspicuous lesions on soybean stems and potentially reducing yields. In addition, M. cribraria congregate on homes and other structures in late fall as they seek overwintering sites, potentially becoming a nuisance pest where populations are large. We examined M. cribraria as a yield reducing pest of soybeans and as a nuisance pest of buildings. Large populations of M. cribraria in caged soybean plots resulted in yield losses of up to 59.6%, and yield reductions were similar in both 2011 and 2012. Several professional-use insecticides were effective in controlling M. cribraria on a variety of building material surfaces, and in some insecticide × surface combinations activity was maintained 30 days post-application. These results contribute to our still developing understanding of this insect as an agricultural and nuisance pest