A new approach to mark termites (Cornitermes cumulans (Kollar) Blattodea: Isoptera) for laboratory bioassays

Behavioral lab bioassays involving termites must be promptly performed to allow intended observations prior to death from dissecation, typical of these soft-bodied insects. To this end, topic markers have been proposed as an alternative to histological stains which, while not always toxic are inevitably lengthy to apply. Among recommended topic markers, gouache is easy to apply, dries out quickly, but it is known affect termites in the long run, being suitable only to short-term bioassays. Its alternative, colored glue, is also easy to apply, but it takes long to dry and it is too dense and heavy, being thus prone to affect termite walking patterns. Here we tested a mix of gouache and colored glue aiming to combine the qualities of both into a suitable topical marker for Cornitermes cumulans termites. Similar patterns of survival presented by marked and unmarked termites ruled out concerns about toxicity of this mixture. Such results were consistent across distinct group densities evidencing that the mixture does not interfere with, nor it is affected by, crowding effects. Because crowding regulates interindividual interactions and these underlie most behaviors, the mixture can be thought to be suitable to behavioral studies. We argue that this 1:2 glue:gouache mixture is an excellent alternative to mark termites for lab bioassays. Being atoxic, cheap, easy to apply, and non-invasive, this mixture may happen to be useful not only for termites but also in bioassaying other similarly soft-bodied insects.

Honeybees use propolis as a natural pesticide against their major ectoparasite

Honeybees use propolis collected from plants for coating the inner walls of their nest. This substance is also used as a natural antibiotic against microbial pathogens, similarly to many other animals exploiting natural products for self-medication. We carried out chemical analyses and laboratory bioassays to test if honeybees use propolis for social medication against their major ectoparasite: Varroa destructor . We found that propolis is applied to brood cells where it can affect the reproducing parasites, with a positive effect on honeybees and a potential impact on Varroa population. We conclude that propolis can be regarded as a natural pesticide used by the honeybee to limit a dangerous parasite. These findings significantly enlarge our understanding of behavioural immunity in animals and may have important implications for the management of the most important threat to honeybees worldwide.

Spatiotemporal elements in a poisoned bait strategy against the long-tailed silverfish (Lepismatidae: Zygentoma)

The long-tailed silverfish Ctenolepisma longicaudatum (Lepismatidae: Zygentoma) is a nuisance problem in buildings and a major concern in museums, libraries and archives where it cause damage to historical and priceless items. We used laboratory bioassays and two field studies of infested buildings to evaluate spatial and temporal elements of a poisoned bait strategy. In both laboratory experiments and field studies, the efficiency of poisoned bait with indoxacarb as the active ingredient was significantly improved by placing many small bait droplets evenly distributed along all edges of the treated area compared to more clustered distributions. Extended duration of bait presence and removal of competing food sources improved the control effect significantly in the laboratory bioassays. Bait-treated populations also showed a significant decline in the number of eggs deposited and emergence of new nymphs. The study supports poisoned bait as an efficient and low risk approach against the long-tailed silverfish in which extended duration of bait presence, wide distribution of bait droplets in combination with sanitation was crucial for control in the infested premises.

Diet affects body color and energy metabolism in the Baikal endemic amphipod Eulimnogammarus cyaneus maintained in laboratory conditions

Proper diet is critical for laboratory-reared animals, as it may affect not only their welfare, but also experimental results. Amphipods (Crustacea: Amphipoda) play important roles in ecosystems and are often used in environmental research. Endemic amphipods from the ancient Lake Baikal are promising for laboratory bioassays; however, there are currently no laboratory cultures. In this work, we determine how different diets affect the color and metabolism of a laboratory-reared Baikal amphipod, Eulimnogammarus cyaneus. We found that in freshly collected blue-colored animals, body color correlated with total carotenoid content. Total carotenoid levels did not differ after long-term (two months) feeding with a close to natural carotenoid-enriched, or even a carotenoid-depleted diet. Nevertheless, antennae color was closer to red in the natural-like diet group. It is likely that the carotenoids from the commercial diet are not properly metabolized in E. cyaneus. The animals fed commercial diets had a higher glycogen content, which may signify a higher metabolic rate. Overall, we show that a carotenoid-enriched diet optimized for decapods is not optimal for amphipods, likely due to different carotenoid compositions, and the diet for long-term rearing of E. cyaneus and other Baikal amphipods requires supplementation.

Isolate locale ale baculovirului entomopatogenic ca o tehnologie de formulare inovatoare, care protejează biopesticidul din degradare a radiației ultraviolete

This paper presents the conceptual conceptual vision a formulation technology for biopesticides in which the active ingredient (baculovirus) is an active coal. Importantly, this indgredient protects the sen-sitive viral DNA from degrading in sunlight, but dissolves in the alkaline insect gut to release the virus, which then infects and kills the pest. We show, using this ingredient, in both laboratory bioassays and field tests, that this can extend the efficacy of the biopesticide well beyond the few hours of existing virus formulations, potentially increasing the spray interval and reducing the need for high application rates. Are presented both theoretical foundations and practical applications and described the results oriented for implementation and functionality of organic agriculture in Republic of Moldova.

Comparing the effects of crude and refined Mammea americana (Mamey apple) leaf extracts on Doralis symphyti (aphids) on ochro (Hibiscus esculentus) plants

The aphid, Doralis symphyti (Homoptera: Aphididae), a harmful pest of many crops, causes direct damage by consuming all plant parts, reducing plant vigour, and indirect damage by honeydew secretion and transmission of several viruses. Due to the problem of pesticide resistance, alternative techniques for chemical control, such as the use of natural insecticides with minimal effects on the environment and natural enemies also coincide with organic agriculture have been the objective of this research. The effects of Mammea (Mammey americana) leaf extracts on the mortality of aphids were evaluated. The mammey extracts (Crude and refined) were tested in the laboratory (bioassays) at 100%, 90%, 80%, 70% and 60% dilution. The 80% was determined to be the most efficient dilution. The refined extract resulted in 100% mortality at 84 hours while the dry leaf and green leaf extracts gave 100% mortality in 96 hours. In the field, the refined extract resulted in 65% mortality, dry leaf crude extract obtained in 43% mortality and the green leaf crude extract gave 25% mortality. The mamey leaf extracts were efficient against the aphid in the laboratory since 100% mortality was obtained for all treatments. The field study found that the green leaf extract obtained 29% mortality, dry leaf extract achieved 47% mortality and the refined extract attained 63% mortality of aphids.

Reproduction of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) and Trissolcus sp. aff. urichi (Hymenoptera: Scelionidae) in Eggs of Nezara viridula (Hemiptera: Pentatomidae) of Different Ages

The study of the interaction between parasitoid and host, especially the age of these organisms, is an important step towards the implementation of biological control programs. Therefore, we investigated the performance of Ooencyrtus submetallicus (Hymenoptera: Encyrtidae) and Trissolcus sp. aff. urichi (Hymenoptera: Scelionidae) parasitizing eggs of Nezara viridula (Hemiptera: Pentatomidae), considering different ages of the parasitoids and the host. We performed four laboratory bioassays: two using females of O. submetallicus and Trissolcus sp. aff. urichi at 24, 48, 72, 96, 120, or 144 hours of age exposed to parasitism in N. viridula eggs (24 h) and two trials with N. viridula eggs at 24, 48, 72, 96, 120, or 144 hours exposed to the parasitism of O. submetallicus and Trissolcus sp. aff. urichi (24 h). We evaluated the percentage of parasitism and emergence, life cycle length, progeny, sex ratio, and the longevity of the parasitoids. The parasitism of O. submetallicus in N. viridula eggs was influenced by the age of the parasitoid, 120 hours being the minimum to obtain better parasitism. From this age on, there is interference in the longevity of the progeny. Trisolcus sp. aff. urichi, at all ages, parasitized N. viridula eggs relatively well, but with almost no emergence of the parasitized eggs. Females of O. submetallicus parasitized and developed in eggs of N. viridula of all ages. Females of Trissolcus sp. aff. urichi parasitized their host, but there was barely any emergence. These pieces of information regarding the breeding methodology contribute to the implementation of new protocols for the multiplication of these parasitoids in the laboratory, and later, their release in the field.

Evaluation of the Bio-Insecticidal Effect of Ricinus communis (Malpighiales: Euphorbiaceae) on the Larvae of Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae)

Since chemical insecticides favor the emergence of resistance and have disastrous consequences for the environment, we became interested in an alternative control method against Spodoptera frugiperda, more respectful for the environment. We therefore evaluated the effectiveness of the bio-insecticidal effects of plants extracts and oil of castor against the fall armyworm in the laboratory. The laboratory bioassays consisted of evaluating the toxicity of the castor plants extracts and oil by contact and ingestion on fourth instar larvae of Spodoptera frugiperda using a leaf dipping method. It emerges from this study that the mortality of the larvae treated with the bio-insecticide and the control solution varies significantly and that the mortality rate was 100% for dose 1; 85% for dose 2 and 70% for dose 3. The mortality rate for the control solution is 10%. These results testify to the good larvicidal activity of the organic insecticide based on oil, leaves and unripe seeds of castor bean on the fall armyworm.

Spray and Pour-On Acaricides Killed Tennessee (United States) Field-Collected Haemaphysalis longicornis Nymphs (Acari: Ixodidae) in Laboratory Bioassays

Haemaphysalis longicornis Neumann (Asian longhorned tick) is an exotic and invasive tick species presenting a health and economic threat to the United States (U.S.) cattle industry due to its ability to transmit pathogens and infest hosts in large numbers. The objective of this study was to evaluate available products at causing H. longicornis mortality in a laboratory bioassay. The efficacy of products was evaluated at label rates using H. longicornis nymphs collected from a cattle farm in eastern Tennessee in two different bioassays (spray or dip) against untreated controls. After exposure, ticks were transferred to clean petri dishes and checked for mortality at 0, 1, 2, 3, 4, 21, 24, and 48 h post exposure. No mortality occurred in the untreated controls, whereas all treated ticks were dead within 24 h of exposure (P < 0.0001). These findings support the hypothesis that currently available spray and pour-on products are effective at causing H. longicornis mortality. We conclude that these acaricides can be used as a component to prevent H. longicornis dispersal and for control in the U.S.