Blood deprivation and heat stress increase mortality in bed bugs (Cimex lectularius) exposed to insect pathogenic fungi or desiccant dust

Bed bugs (Cimex lectularius L.) have returned as a nuisance pest in the last 20 years. Different bed bug control measures in combination have not been thoroughly studied, although induction of multiple stressors may improve extermination. The effects of heat stress only, heat stress followed by exposure to insect pathogenic fungi, and heat stress followed by exposure to desiccant dust on starved and blood-fed bed bugs were investigated. Five days at 22 °C (control), 32 °C, 34 °C, or 36 °C (heat stress) did not cause mortality in adults. However, their starved first instar nymphs produced after heat stress suffered mortalities of 33%, 56% and 100%, respectively. Exposure to insect pathogenic fungi after heat stress increased the mortality of adults and their progeny compared to exposure to fungi without heat stress. The beneficial effects of heat stress were not observed in blood-fed bed bugs. Desiccant dust killed all nymphs within 2 days and all adults within 3 days regardless of previous heat stress, but survival time was prolonged by access to blood. This study highlights the advantage of combining different methods in pest management, and points to heat stress combined with blood deprivation as possible management elements to increase the control success.

Blow fly responses to semiochemicals produced by decaying carcasses

Volatiles from mouse carcasses in decay stages ranging from fresh to 33 days old were used to investigate oriented flight and landings in male and female blow flies of Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). Oriented flight increased significantly from 36% towards fresh carcasses to 68%, 61% and 65% towards carcasses aged 3 days, 6 days and 9 days, respectively. Carcasses aged 20 days and 33 days were significantly less attractive, achieving 51% and 41% attraction, respectively. No differences emerged between the sexes in oriented flight, but a significant increase in female landings at the most attractive carcasses was observed. Headspace collections from the different stages of decay showed a succession in the volatile profile emitted from the carcasses and identified nine chemicals which peak in quantity in concurrence with the most attractive stages of decay. Three of these chemicals also showed dose-response effects as indicated by a significant correlation between the amount present and the proportion of flies responding. Blow flies are important pests and efficient traps are needed. The significant interaction between fly sex and carcass age highlights behavioural differences between male and female blow flies which can be exploited in blow fly trapping. Three new volatile chemicals, butylated hydroxyl toluene, 3-hydroxy-2-butanone and nonanal, emitted from dead mice are suggested as potential attractants.

Bed bugs, their blood sources and life history parameters: a comparison of artificial and natural feeding

A blood-feeding system that utilizes a small amount of whole heparinized human blood in parafilm bags is described in detail, and similarities and differences between artificially fed and naturally rodent-fed bed bugs (Hemiptera: Cimicidae) are discussed. Blood with high levels of heparin (10%) was unsuitable for artificial colony rearing, whereas bed bugs fed on 1% heparinized blood and those that naturally ingested rat blood completed their lifecycle with similar stage structures over time, with no significant differences in mortality. No differences in feeding efficiency or fertility were found in a direct comparison of bed bugs maintained under each of these two treatments, but analysis of the full lifecycle revealed that artificially fed bed bugs became significantly smaller and laid fewer eggs than rodent-fed bed bugs. The level of membrane stretching regulated the number of bed bugs that fed. When the membrane was stretched to twice its length and width, 96% of bed bugs successfully fed through the parafilm. Whole heparinized blood that was stored at 6 °C for ≥ 14 days failed to retain its nutritional value and the amount of blood consumed and number of consecutive moults were significantly reduced.

Wind tunnel behavioural response and field trapping of the blowfly Calliphora vicina

The attraction of the blowfly Calliphora vicina Robineau-Desvoidy, 1830 (Diptera: Calliphoridae) to single synthetic compounds, blends and authentic odours was investigated in a wind tunnel. A total of 1850 C. vicina (1750 females and 100 males) were tested. A comparison of male and female responses showed significant differences in attraction between the sexes. Females were more attracted than males to liver odour. The attraction of females lay in the ranges of 0-22% for single compounds, 26-64% for synthetic blends and 58-88% for authentic odours. Dimethyl trisulphide was the most attractive single compound. Significant improvement in attraction was achieved with blends and a three-component lure, consisting of dimethyl trisulphide, mercaptoethanol and o-cresol, was found to be the best solution for field trapping of C. vicina. Authentic odours from dead fish and mice were significantly more attractive than liver and the three-component blend, and the blend and liver were similarly effective as attractants. Field tests support the results of the wind tunnel study and a high number of C. vicina were caught in funnel traps. Overall, 99.1% of the specimens caught were females.