Effect of Prey Species and Prey Densities on the Performance of Adult Coenosia attenuata

Mass production of Coenosia attenuata Stein at low cost is very important for their use as a biological control agent. The present study reports the performance of C. attenuata adults when reared on Drosophila melanogaster Meigen or Bradysia impatiens (Johannsem). Different densities (6, 9, 15, 24 and 36 adults per predator) of D. melanogaster or (6, 12, 24, 36 and 48 adults per predator) of B. impatiens were used at 26 ± 1 °C, 14:10 (L:D) and 70 ± 5% RH. The results concluded that C. attenuata adults had higher fecundity, longer longevity and less wing damage when reared on B. impatiens adults compared to D. melanogaster adults. Additionally, C. attenuata adults demonstrated greater difficulty catching and carrying heavier D. melanogaster adults than lighter B. impatiens adults. In this case, 12 to 24 adults of B. impatiens daily per predator were considered optimal prey density in the mass rearing of adult C. attenuata.

Gravity and active acceleration limit the ability of killer flies ( Coenosia attenuata ) to steer towards prey when attacking from above

Insects that predate aerially usually contrast prey against the sky and attack upwards. However, killer flies ( Coenosia attenuata ) can attack prey flying below them, performing what we term ‘aerial dives'. During these dives, killer flies accelerate up to 36 m s −2 . Although the trajectories of the killer fly's dives appear highly variable, proportional navigation explains them, as long as the model has the lateral acceleration limit of a real killer fly. The trajectory's steepness is explained by the initial geometry of engagement; steep attacks result from the killer fly taking off when the target is approaching the predator. Under such circumstances, the killer fly dives almost vertically towards the target, and gravity significantly increases its acceleration. Although killer flies usually time their take-off to minimize flight duration, during aerial dives killer flies cannot reach the lateral accelerations necessary to match the increase in speed caused by gravity. Since a close miss still leads the predator closer to the target, and might even slow the prey down, there may not be a selective pressure for killer flies to account for gravity during aerial dives.

First report of Coenosia attenuata (Stein, 1903) (Diptera, Muscidae) in Uruguay, confirmed by DNA barcode sequences

Coenosia attenuata (Stein, 1903) is a predatory fly which feeds on other insects and can be used as a possible biological control agent. We report this insect in Uruguay for the first time. The flies were found in greenhouses on tomatoes and sweet peppers and identified using both DNA barcoding and morphological characteristics.

Interception by two predatory fly species is explained by a proportional navigation feedback controller

When aiming to capture a fast-moving target, animals can follow it until they catch up, or try to intercept it. In principle, interception is the more complicated strategy, but also more energy efficient. To study whether simple feedback controllers can explain interception behaviours by animals with miniature brains, we have reconstructed and studied the predatory flights of the robber fly Holcocephala fusca and killer fly Coenosia attenuata . Although both species catch other aerial arthropods out of the air, Holcocephala contrasts prey against the open sky, while Coenosia hunts against clutter and at much closer range. Thus, their solutions to this target catching task may differ significantly. We reconstructed in three dimensions the flight trajectories of these two species and those of the presented targets they were attempting to intercept. We then tested their recorded performances against simulations. We found that both species intercept targets on near time-optimal courses. To investigate the guidance laws that could underlie this behaviour, we tested three alternative control systems (pure pursuit, deviated pursuit and proportional navigation). Only proportional navigation explains the timing and magnitude of fly steering responses, but with differing gain constants and delays for each fly species. Holcocephala uses a dimensionless navigational constant of N ≈ 3 with a time delay of ≈28 ms to intercept targets over a comparatively long range. This constant is optimal, as it minimizes the control effort required to hit the target. In contrast, Coenosia uses a constant of N ≈ 1.5 with a time delay of ≈18 ms, this setting may allow Coenosia to cope with the extremely high line-of-sight rotation rates, which are due to close target proximity, and thus prevent overcompensation of steering. This is the first clear evidence of interception supported by proportional navigation in insects. This work also demonstrates how by setting different gains and delays, the same simple feedback controller can yield the necessary performance in two different environments.

Código de barras de ADN revela el primer registro de Coenosia attenuata Stein (Diptera: Muscidae) en Honduras

Se registra la mosca depredadora Coenosia attenuata Stein por primera vez en Honduras. Un análisis molecular de código de barras del gen COI fue usado para la identificación.

First record of Coenosia attenuata Stein, 1903 (Diptera: Muscidae) in Venezuela

La mosca tigra, Coenosia attenuata Stein, 1903 es un importante depredador de insectos pequeños como moscas blancas, moscas del mantillo, minadores, y otros pequeños hemípteros y lepidópteros. El objetivo de esta investigación es reportar la presencia de esta especie por primera vez en Venezuela, donde ha sido observada en casas de cultivo ubicadas en el estado Miranda, depredando adultos de Trialeurodes vaporariorum (Westwood, 1856) y de moscas de los géneros Bradysia Winnertz, 1867 y Liriomyza Mik, 1894 sobre crisantemo (Chrysanthemun sp.), gerbera (Gerbera jamesonii Bolus y Hook), lechuga (Lactuca sativa L.) y pimentón (Capsicum annuum L.). La presencia de la mosca tigra en Venezuela subraya la necesidad de investigaciones sobre su uso potencial como un agente de biocontrol de insectos plaga. The tiger-fly Coenosia attenuata Stein, 1903 is an important predator of small insects such as whiteflies, fungus gnats, leafminers, and other small Hemiptera and Lepidopters. The aim of this research is to report the occurrence of this species for first time in Venezuela, where it has been observed in greenhouses located in Miranda state, predating adults of Trialeurodes vaporariorum (Westwood, 1856) and of the fly genera Bradysia Winnertz, 1867 and Liriomyza Mik, 1894 on chrysanthemum (Chrysanthemum sp.), gerbera (Gerbera jamesonii Bolus ex Hook), lettuce (Lactuca sativa L.) and pepper (Capsicum annuum L.). The occurrence of the tiger-fly in Venezuela underlines the necessity for researches into its potential use as a biocontrol agent of insect pests.