A new report of three parasitoids of the cogongrass gall-midge Orseolia javanica Kieffer & Van Leeuwen-Reijnvaan (Diptera: Cecidomyiidae) in Bogor West Java

The cogongrass gall midge, Orseolia javanica, has been identified as a biological control agent with the ability to specifically attack cogongrass (Imperata cylindrica) or known in Indonesia as alang-alang. However, in the field, the cogongrass gall midge has a high parasitism by insect parasitoids, which could lead to population collapse. Information regarding the insect parasitoids of the cogongrass gall midge is a very limited. The objectives of this study was to describe and identify the new reported cogongrass gall midge parasitoids in Gunung Gadung cemetery in Cipaku, South Bogor District, Bogor. This study was conducted by taking the cogongrass galls in the field, maintaining in the laboratory, identificating the parasitoids, and calculating the percentage of parasitism. The study has been conducted from August 2020 to May 2021. Three new reported parasitoids were identified on O. javanica in addition to five already known parasitoid, they were Eurytoma sp. (Hymenoptera: Eurytomidae), Lamprotatus sp. (Hymenoptera: Pteromalidae), and Nigeriella sp. (Hymenoptera: Agaonidae). These parasitoids may be able to reduce the effectiveness of the cogongrass gall-midge in controlling the cogongrass. Their morphological characters, descriptions, and percentage of parasitism are presented.

Did the Colonial mita Cause a Population Collapse? What Current Surnames Reveal in Peru

We present quantitative evidence that the mita introduced by the Spanish crown in 1573 caused the decimation of the native-born male population. The mass baptisms after the conquest of Peru in 1532 resulted in the assignation of surnames for the first time. We argue that past mortality displacement and mass out-migration were responsible for differences in the surnames observed in mita and non-mita districts today. Using a regression discontinuity and data from the Peruvian Electoral Roll of 2011, we find that mita districts have 47 log points fewer surnames than non-mita districts, and fewer surnames exclusive to one location.

K-Means Clustering of Abalone Populations Using an Incomplete Dataset

This report investigates the distribution of abalone data collected off of the coast of Tasmania, Australia in 1994. Analysis of this data is used to determine whether or not the dataset includes groups which are unusual and possibly indicative of the abalone population collapse that has occurred in Tasmania since the data was collected. As a side effect, some of the abalone population distribution data that was reportedly collected in (Nash, 1994) but neither published in (Nash, 1994) nor in the UCI data repository (Nash, 1995) has been reconstituted and made available in the appendix.

Northern shrimp Pandalus borealis population collapse linked to climate-driven shifts in predator distribution

The northern shrimp (Pandalus borealis Krøyer) population in the Gulf of Maine collapsed during an extreme heatwave that occurred across the Northwest Atlantic Ocean in 2012. Northern shrimp is a boreal species, and reaches its southern limit in the Gulf of Maine. Here we investigate proximate causes for the population collapse using data from fishery-independent surveys, environmental monitoring, and the commercial fishery. We first examined spatial data to confirm that the decline in population estimates was not due to a major displacement of the population, and then tested hypotheses related to fishing mortality and shifts in predation pressure. Fishing mortality may have contributed but could not explain the magnitude of the decline or the disappearance of pre-exploitable size individuals. Stomach contents analysis and biomass trends revealed no new fish predators of shrimp. However, longfin squid (Doryteuthis pealeii Lesueur) was unique among all species in showing time-series biomass peaks during spring, summer and fall of 2012, and spatial overlap with northern shrimp was unusually high in 2012. Longfin squid is a voracious and opportunistic predator that consumes crustaceans as well as fish. We hypothesize that the warmer temperatures of 2012 not only led to expansion of longfin squid distribution in Gulf of Maine, but had differential effects on migration phenology that further increased spatial overlap with northern shrimp. The weight of our evidence suggests that longfin squid predation was likely a significant factor in the collapse of northern shrimp in the Gulf of Maine.

Population collapse in Congo rainforest from 400 CE urges reassessment of the Bantu Expansion

The present-day distribution of Bantu languages is commonly thought to reflect the early stages of the Bantu Expansion, the greatest migration event in African prehistory. Using 1149 radiocarbon dates linked to 115 pottery styles recovered from 726 sites throughout the Congo rainforest and adjacent areas, we show that this is not the case. Two periods of more intense human activity, each consisting of an expansion phase with widespread pottery styles and a regionalization phase with many more local pottery styles, are separated by a widespread population collapse between 400 and 600 CE followed by major resettlement centuries later. Coinciding with wetter climatic conditions, the collapse was possibly promoted by a prolonged epidemic. Comparison of our data with genetic and linguistic evidence further supports a spread-over-spread model for the dispersal of Bantu speakers and their languages.