First detection of Megaselia scalaris (Loew) (Diptera: Phoridae) as a facultative endoparasitoid of Nezara viridula (L.) (Hemiptera: Pentatomidae)

Background The phorid fly Megaselia scalaris (Loew) (Diptera: Phoridae) is an omnivorous species, capable of exploring a large variety of environments and ecological niches. It is known as an important detritivore species with maggots feeding on a variety of food of both animal and plant origin. Results The present study reports M. scalaris as an endoparasitoid attacking colonies of the southern green stink bug Nezara viridula (L.) for the first time. This case of parasitism was observed inside rearing cages of N. viridula at the Plant Protection Research Institute, Dokki, Egypt in August 2020. We firstly identified adult individuals of M. scalaris which were found moving erratically within the cages using relevant identification keys. To verify that N. viridula individuals are parasitized by the same parasitoid and they are not infected with other parasitoids, some of the parasitized bugs were transferred to a separate cage at the same laboratory conditions and the developmental stages of the dipteran parasitoid were observed until the adult emergence. Conclusion The present investigation revealed that M. scalaris could be included to the recorded parasitoid species of N. viridula, and further studies should be carried out to assess the efficacy of this fly as a biocontrol agent.

New data on invasive insects in the republic of Сrimea

In recent years, the emergence of new invaders has been discovered in Crimea – the mealy lantern fly Metcalfa pruinosa (Say, 1830) (Hemiptera: Auchenorrhyncha: Flatidae), the indian wax scale Ceroplastes ceriferus (Fabricius, 1798) (Hemiptera: Coccoidea: Coccoidea), the southern green stink bug Nezara viridula (Linnaeus, 1758) (Hemiptera: Heteroptera: Pentatomidae), the stink bug Oxycarenus lavaterae (Fabricius, 1787) (Hemiptera: Heteroptera: Lygaeidae) and palm moth Paysandisia archon (Burmeister, 1880) (Lepidoptera: Castniidae). Timely information on the penetration of new alien species that damage agricultural and ornamental crops into the entomofauna of Crimea, their distribution, biological characteristics that are relevant for specialists in the field of plant protection and landscape architecture. The number of mealy lantern fly has increased over the years of observations, and the list of host plants has also expanded, which has confirmed its polyphagia. In Crimea, a pest has appeared that can cause significant damage to fruit, berry, nut-bearing and ornamental crops. During the years of research, we discovered another alien species – the indian wax scale. As a result of damage to ornamental crops, individual branches dried out and some plants died. We assume that this phytophage was brought to the Crimea with planting material, because it occurs focally on objects of landscape architecture. Since 2018, palm trees have been damaged by the palm moth – one of the invasive pests of these plants on the southern coast of Crimea. Caterpillars damage the vascular system and the plant's growth point. As a result of the damage caused, the plants die. Since the same year, a new alien species, the southern green stink bug, has shown harmfulness on vegetable, berry and flower crops, as well as on weeds, and in 2020, for the first time in the Crimea, in the Nizhnegorsk region, another stink bug, O. lavaterae, was found on a linden. There is little information about this insect. It can form massive clusters on linden and hibiscus bark.

Retention of Pantoea agglomerans Sc1R across stadia of the southern green stink bug, Nezara viridula (L.) (Hemiptera: Pentatomidae)

Southern green stink bug [Nezara viridula (L.)] adults and other pentatomid pests can transmit pathogens (e.g., the bacterium Pantoea agglomerans) that cause disease in cotton (Gossypium hirsutum L.) and other high-value cash crops worldwide. First instars of N. viridula were recently shown to ingest P. agglomerans strain Sc1R with rifampicin-resistance, and to retain the pathogen to the 2nd instar. The objective of this study was to determine the acquisition of P. agglomerans Sc1R by early instars of N. viridula and determine persistence of P. agglomerans Sc1R across subsequent stadia. In three trials, early instars (1st and 2nd) were exposed to P. agglomerans Sc1R and subsequently maintained to adulthood; cohorts were sampled at 3rd and 5th instars, as well as adults. In every trial, P. agglomerans Sc1R was detected in all stadia, including adults, but significantly higher frequencies of infection than expected were observed at the initial stage of infection (either 1st or 2nd instar). Higher densities of P. agglomerans Sc1R were detected in 1st and 2nd instars, and lower densities were observed in subsequent stadia. Densities of innate microbiota were generally lower when the initial stage of exposure was at 1st instar than when the initial stage of exposure was at the 2nd instar. Overall, half of the adults possessed P. agglomerans Sc1R. These findings demonstrated that N. viridula nymphs can acquire P. agglomerans Sc1R and retain the pathogen to adulthood. Potential avenues of research to further elucidate the implications of nymphs harboring pathogens to adulthood are discussed.