Derocephalus angusticollis

Like other flies within Neriidae, D. angusticollis has characteristic dorsocentral bristles located for the most part on their thorax as an identification marker.[4] The number of pairs of bristles varies within the genus; D. angusticollis usually has two pairs instead of one pair.[5] Variation has been observed on parts other than the thorax. Certain flies had a lack of bristles or fewer than the average due to genetic factors and environmental factors, such as the quality of diet.[4]

The flies' diet consists of rotting vegetation, bark, mold, and sap.[7] One particular study found that a nutrient-rich diet for this fly was one of a higher protein and carbohydrate content.[8] The quality of the diets of parents, in particular, has been found to have effects on the phenotype of the offspring. Mothers with nutrient-rich diets were found to lay larger eggs that also developed faster.[7] Likewise, fathers that were raised on high-nutrient diets had larger adult offspring, improving the overall fitness of the offspring.[7][9]

Researchers have demonstrated that early differences in nutrient content can impact D. angusticollis's ability to age successfully.[10] Male early life condition was manipulated by varying nutrient content of larval diet, and the interactions that adult males had later on in life with other adult males were also intentionally controlled and manipulated in the experiment. Males fed with high nutrient levels as larvae were able to develop more quickly, and reached their reproductive peak earlier on.[10] Males with a nutrient-rich diet also experienced more rapid reproductive aging and ultimately died sooner than their poorly fed counterparts.[10] High nutrient condition early in life is associated with rapid aging even in the absence of male-male conflicts that damage one's longevity.[10]

The effect of the quality of food having an effect on the fitness of the male is specific to their developmental diets . Where male D. angusticollis flies reared on nutrient-poor diets would develop smaller testes and accessory glands, while those that were already adults on a rich diet showing no effects.[11] The amount of protein as well as the age of the adult male can also affect the viability of their offspring. Where younger male adults with less protein in their diet had less viable offspring, yet as they grow older the viability of their offspring increases.[12]

Derocephalus angusticollis practice polyandrous mating behavior.[13] The possibility of a non-genetic mechanism of inheritance has been explored in this species. Researchers have investigated D. angusticollis to search for evidence of telegony, which suggests that previous partners might be able to influence traits in offspring raised by subsequent males mating with the same female.[13] Males are able to transmit environmentally obtained conditions through paternal effects on the offspring's body size. These effects were experimentally shown to come from a previous male that the female had mated with, not the genetic father of the offspring.[13] The presence of telegony was only observed when females were exposed to the first male after mating, implying that the mechanism is semen-dependent, and not correlated with female choice mechanisms.[13]

Females are less active and spend most of their time in the same area drinking sap from damaged trees.[15] Females may aggregate at the same oviposition site as well as act more aggressively with others. Their aggressive behaviors are different from males such as flicking their wings or using their forelegs to combat other females.[16] Conversely, males are more active in moving about aggregation sites in competing for, searching for, and copulating with mates. Some have argued that this more active behavior increases their visibility and probability of coming into contact with predators.[15]

Derocephalus angusticollis use chemical signaling by their levels of cuticular hydrocarbons (CHCs) during their social interactions. Both genders have been observed to alter the levels of CHCs depending on where they fall in the social hierarchy of dominance. Subordinates show similar patterns between sexes while dominant flies have different patterns of CHC levels.[16]

The main predator that targets this species is skinks (Eulamprus tenuis). In the wild, skinks sneak up on the flies from below. During certain studies that required flies to be identified by markers, there was a concern that the markers increased risk of predation, as the markers were attached to the abdomen to make them visible from above. Due to predators sneaking onto their prey from below, however, researchers have speculated that identification markers on the top part of the flies as used in observations may not make them more visible, as skinks' line of sight is limited to the bottom half of the fly.[15]

In a study that compared wild and captive D. angusticollis flies, researchers observed differences in both the speed of development as well as the age of mortality. Flies in the wild had accelerated development and did not live as long as those in captivity. This is likely due to varying conditions in the wild (harsh temperatures, risk of predation) as opposed to controlled conditions in the lab.[15]