Inheritance of Two Traits With High Plasticity, Developmental Speed, and Body Size, in Tenebrio molitor (Coleoptera: Tenebrionidae).

The study of inheritance of quantitative traits of high plasticity in insects has been limited. The heritability of larval development time and body weight in Tenebrio molitor L. was determined using the method of parent-offspring regression. The parental group of adults obtained from a cohort from one day of oviposition from a stock colony was divided into 28 class groups according to their larval development time and pupal weight. The progeny resulting from these parental classes was grouped in experimental units and allowed to develop to the pupal stage. Means of larval development time and pupal weight of the progeny were compared with their parental class levels using linear regression. The selection of larval development time and pupal weight in the parental classes had a significant impact on the means of larval development time and pupal weight of the progeny. The regression coefficients for larval development time and pupal weight were 0.626 ±â€…0.02 and 0.408 ±â€…0.02, respectively. These values represent the proportion of genetic determination of these two traits based on the principles of the method of parent-offspring regression. The apparent independence of larval development time and pupal weight based on their poor linear correlation is discussed.

Body Mass Increase Induced by Eight Years of Artificial Selection in the Yellow Mealworm (Coleoptera: Tenebrionidae) and Life History Trade-offs.

Efforts to improve rearing conditions of Tenebrio molitor L. (Coleoptera: Tenebrionidae) for insect biomass production included selecting for larger size pupae. The effects of an 8-yr continuous selection of T. molitor pupae for larger size were studied. Data consisting of daily counts and weights of pupae were analyzed using regression to determine the effects of selection over time. A preliminary evaluation of food conversion, growth, fecundity, and larval survival was done to compare ancestral versus selected strains. A significant positive correlation was identified between pupal size and time indicating a significant increase in pupal size over time in the selected T. molitor strain. A preliminary comparison of ancestral and selected strains showed significantly larger pupal size, growth rate, fecundity, and efficiency of conversion of ingested food in the selected strain. However, the selected strain also showed significantly lower larval survival than the ancestral strain. The low larval survival impacted the overall productivity of the selected strain resulting in no significant differences in biomass production when compared with the ancestral strain. The potential of using selection to improve biomass productivity in T. molitor is discussed.

Differential Sharing of Chemical Cues by Social Parasites Versus Social Mutualists in a Three-Species Symbiosis.

Chemical recognition systems are crucial for maintaining the unity of social insect colonies. It has been proposed that colonies form a common chemical signature, called the gestalt odor, which is used to distinguish colony members and non-members. This chemical integration is achieved actively through social interactions such as trophallaxis and allogrooming, or passively such as through exposure to common nest material. When colonies are infiltrated by social parasites, the intruders often use some form of chemical mimicry. However, it is not always clear how this chemical mimicry is accomplished. Here, we used a three-species nesting symbiosis to test the differences in chemical integration of mutualistic (parabiotic) and parasitic ant species. We found that the parasite (Solenopsis picea) obtains chemical cues from both of the two parabiotic host ant species. However, the two parabiotic species (Crematogaster levior and Camponotus femoratus) maintain species-specific cues, and do not acquire compounds from the other species. Our findings suggest that there is a fundamental difference in how social mutualists and social parasites use chemicals to integrate themselves into colonies.

Alzheimer disease: are we intervening too late? Pro.

The affirmative position is argued in response to the question of whether intervention in the disease course of Alzheimer disease (AD) occurs too late. AD is not a singular, homogeneous disease, but rather a final common pathway or end-point that can be arrived at through multiple routes. As part of the affirmative argument, there is a delineation of two long-term trajectories leading to AD: (1) normal elderly progression to AD, and (2) depressed elderly progression to AD. In documenting normal elderly devolution into AD, two "normal" elderly pre-AD or prodromal stages are discussed: age-associated memory impairment (AAMI) and mild cognitive impairment (MCI). Data are provided evidencing significantly high conversion rates from these pre-AD stages to actual AD. Using the same paradigmatic approach that is used in documenting normal elderly decline into AAMI and MCI with eventual conversion to AD; there is explication of depressed elderly conversion to AD. The long-term, multiphasic disease progression of major depression without dementia to depressive dementia to final conversion to AD is brought into focus as another example of why intervention must occur prior to actual conversion to AD. Depression is defined as a cognitive syndrome and risk factor for AD requiring aggressive targeted intervention. AD does not just come suddenly out of nowhere. First intervention must occur during the pre-AD phases in an attempt to prevent, delay, and interrupt long-term neurodegenerative processes involved in both normal elderly and depressed elderly conversion to AD. A primary strategy proposed is to delay onset of AD. Population statistics indicate that if AD is delayed by a modest 1 year, there would be 9.5 million fewer cases by 2050, resulting in significant reduction in burden of disease. Data show early intervention with cognitive stimulation (mental exercise), physical exercise, aggressive treatment of AD risk factors and excess disability, psychotherapy, and other nonpharmacological interventions in combination with each other and/or with medications can result in delay of onset of AD. First intervention at time of diagnosis of AD is too late, when by definition, final conversion to AD has already occurred. When we have knowledge to successfully intervene earlier, why would we not want to do so.

Self-Selection of Agricultural By-Products and Food Ingredients by Tenebrio molitor (Coleoptera: Tenebrionidae) and Impact on Food Utilization and Nutrient Intake.

Nutrient self-selection was used to determine optimal intake ratios of macro-nutrients by Tenebrio molitor L. larvae. Self-selection experiments consisted of 9 combinations (treatments) of 8 ingredients, from a total of 20 choices, radially distributed in a multiple-choice arena presented to groups of 100 T. molitor larvae (12th-13th instar). Larvae freely selected and feed on the pelletized ingredients for a period of 21 days at 27 °C, 75% RH, and dark conditions. Consumption (g) of each ingredient, larval live weight gained (mg), and frass production were recorded and used to calculate food assimilation and efficiency of conversion of ingested food. The macro-nutrient intake ratios were 0.06 ± 0.03, 0.23 ± 0.01, and 0.71 ± 0.03 for lipid, protein, and carbohydrate, respectively on the best performing treatments. The intake of neutral detergent fiber negatively impacted food assimilation, food conversion and biomass gain. Food assimilation, food conversion, and biomass gain were significantly impacted by the intake of carbohydrate in a positive way. Cabbage, potato, wheat bran, rice bran (whole and defatted), corn dry distillers' grain, spent brewery dry grain, canola meal and sunflower meal were considered suitable as T. molitor diets ingredients based on their relative consumption percentages (over 10%) within treatment.

Recognition in a social symbiosis: chemical phenotypes and nestmate recognition behaviors of neotropical parabiotic ants.

Social organisms rank among the most abundant and ecologically dominant species on Earth, in part due to exclusive recognition systems that allow cooperators to be distinguished from exploiters. Exploiters, such as social parasites, manipulate their hosts' recognition systems, whereas cooperators are expected to minimize interference with their partner's recognition abilities. Despite our wealth of knowledge about recognition in single-species social nests, less is known of the recognition systems in multi-species nests, particularly involving cooperators. One uncommon type of nesting symbiosis, called parabiosis, involves two species of ants sharing a nest and foraging trails in ostensible cooperation. Here, we investigated recognition cues (cuticular hydrocarbons) and recognition behaviors in the parabiotic mixed-species ant nests of Camponotus femoratus and Crematogaster levior in North-Eastern Amazonia. We found two sympatric, cryptic Cr. levior chemotypes in the population, with one type in each parabiotic colony. Although they share a nest, very few hydrocarbons were shared between Ca. femoratus and either Cr. levior chemotype. The Ca. femoratus hydrocarbons were also unusually long-chained branched alkenes and dienes, compounds not commonly found amongst ants. Despite minimal overlap in hydrocarbon profile, there was evidence of potential interspecific nestmate recognition -Cr. levior ants were more aggressive toward Ca. femoratus non-nestmates than Ca. femoratus nestmates. In contrast to the prediction that sharing a nest could weaken conspecific recognition, each parabiotic species also maintains its own aggressive recognition behaviors to exclude conspecific non-nestmates. This suggests that, despite cohabitation, parabiotic ants maintain their own species-specific colony odors and recognition mechanisms. It is possible that such social symbioses are enabled by the two species each using their own separate recognition cues, and that interspecific nestmate recognition may enable this multi-species cooperative nesting.

Combining DNA barcoding and morphological analysis to identify specialist floral parasites (Lepidoptera: Coleophoridae: Momphinae: Mompha).

Close interactions between insects and plants have played a major role in the evolution of both these diverse groups of organisms. Studying these interactions, however, can be difficult because many insects, especially parasites, impinge most strongly on plants during larval stages when they are morphologically difficult to identify, and many belong to diverse groups for which most species remain undescribed. We used DNA barcoding to identify nondescript lepidopteran larvae that regularly parasitize flower buds of the coastal dune endemic Camissoniopsis cheiranthifolia (Onagraceae). We obtained cytochrome oxidase 1 mitochondrial DNA sequences from 201 parasite specimens from across the host geographical range. The Barcode of Life Database Identification System combined with Bayesian analysis grouped all 15 parasite haplotypes in a distinct, monophyletic clade within the genus Mompha (Lepidoptera: Coleophoridae: Momphinae), a group known to be host specialists on plants of the Onagraceae. Species identity and phylogenetic affinities within Mompha could not be confirmed because few barcode sequences exist from this diverse and poorly known group of moths. However, morphological analysis, including detailed dissection of genitalia for a subsample of 23 reared adults and comparison with known species of Mompha, also indicated that the larvae parasitizing C. cheiranthifolia constitute a distinct and undescribed species within this genus. Knowing that floral parasitism of C. cheiranthifolia involves a single, putatively host-specific microlepidopteran greatly facilitates formulating and testing hypotheses concerning how floral parasitism has promoted the evolution of striking floral diversity within this species. More generally, DNA barcoding combined with morphological analysis can greatly hasten identification of problematic specimens and enhance our understanding of the diversity, ecology and evolution of plant-insect interactions.