Ultrastructural and functional aspects of the spermatheca in the american harlequin bug, Murgantia histrionica (Hemiptera: Pentatomidae)

The spermatheca of Murgantia histrionica (Hahn) was investigated using fluorescence, scanning and transmission electron microscopy. The aim of the study was to elucidate the structure of this organ, pointing out differences between mated and unmated females. Results have shown an elaborated cuticular structure associated with muscular and glandular tissues. The spermatheca is joined with the common oviduct by the spermathecal duct, forming a thin saccular dilation through two consecutive invaginations. The distal part of the organ is formed by a series of two communicating cuticular chambers. The first cylindrical-shaped chamber, corresponding to the coiled region, is wrapped by longitudinal muscular fibers suspended between two cuticular flanges. The contractions of these fibers compress a deformable zone of the cylinder, pumping the sperm toward the spermathecal duct. Without contractions the cylinder results to be isolated from the proximal part of the spermatheca by means of a valve. The second chamber, corresponding to the spermatheca, is made of two parts: a truncated-conical sub chamber, with a constant cuticular thickness, bearing on itself the distal flange, where muscular fibers are attached. The second part is a bulb-like structure wrapped in a glandular epithelium. The secretory units are composed by two cells: a secretory cell and an associated duct cell. Every evacuating duct shows a little reservoir just after the terminal apparatus, and converge inside the distal bulb after a tortuous path. The functional implications of this structure in the reproductive biology of M. histrionica are discussed

Semiochemicals, semiophysicals and their integration for the development of innovative multi-modal systems for agricultural pests’ monitoring and control

4openInternationalSemiochemicals are informative molecules emitted by living organisms that affect the behavior of receivers. As herbivorous insects are primarily thought to depend on olfaction and taste for their intra- and interspecific communication, semiochemicals have been widely studied for pest management applications. However, given that pest behavior does not rely on just one communication modality, stimuli of physical nature, such as light, sounds and vibrations, can also be used to manipulate insect-insect or insect-plant interactions. Moreover, stimuli of different natures can be combined in a multi-modal pest management program to increase the overall efficacy. Besides the widespread use of both chemical and physical signals in multimodal insect communication, the integration of stimuli has hardly been implemented for hardly any crop. This review introduces the term semiophysicals as opposed to semiochemicals and focuses on pest behavioral manipulation by discussing three main approaches; i) manipulation of pest orientation through attractive/repellent stimuli, ii) inhibition or promotion of specific pest behaviors and iii) interference with intraspecific communication through disruptive stimuli. For each approach, we provide examples of use of both semiochemicals and semiophysicals. Lastly, we describe the case study of the vineyard agroecosystem in the Trento province, where a multi-pest management program has been successfully developed, and we discuss future perspectives.openNieri, R.; Anfora, G.; Mazzoni, V.; Rossi Stacconi, M.V.Nieri, R.; Anfora, G.; Mazzoni, V.; Rossi Stacconi, M.V

Preliminary data on Stegobium paniceum (L.) larval head sensilla

Sensory structures of Stegobium paniceum (L.) head have been investigated under Scanning and Transmission Electron Microscopes and described. Their possible function is hypothesized

First report on classical biological control releases of the larval parasitoid Ganaspis brasiliensis against Drosophila suzukii in northern Italy

Current management strategy of the invasive fruit fly Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) exploits different tools but relies mainly on chemical control. In the invaded areas, the local natural enemy community mostly consists of generalist pupal parasitoids unable to control the pest efficiently. Conversely, in the pest native area, there are more specialized sympatric larval parasitoids attacking D. suzukii. Following foreign explorations and quarantine risk assessments, the larval endoparasitoid Ganaspis brasiliensis (Ihering) (Hymenoptera: Figitidae) was selected as the best candidate for classical biological control programs. In 2021, the first ever propagative biocontrol program using a Japanese G1 lineage of G. brasiliensis started in Italy. Here we report the results of the first year of releases in the province of Trento (Northeast Italy), wherein G. brasiliensis was released in 12 locations. Pre- and post-release samplings on fresh and fallen fruits were performed around the release points to assess the recapture rate, the impact of the exotic parasitoid on D. suzukii and its potential interactions with local non-target species. After releases, G. brasiliensis was recovered at 50% of the locations. The exotic parasitoid only emerged from D. suzukii, mostly from fresh fruit still on the plant. Post-overwintering monitoring revealed the presence of a four G. brasiliensis individuals at two release locations

Conservazione a basse temperature di stadi immaturi di Ganaspis brasiliensis agente di controllo biologico classico di Drosophila suzukii

L’importazione, l’allevamento e i rilasci del parassitoide asiatico Ganaspis brasiliensis (Ihering) (Hymenoptera: Figitidae) sono in corso nei principali paesi minacciati dal suo ospite Drosophila suzukii (Matsumura) (Diptera: Drosophilidae). Nonostante l’allevamento massale del parassitoide e la pianificazione dei rilasci siano delle procedure costose e impegnative, la tecnica della conservazione a basse temperature potrebbe permettere di ottimizzare la produzione di questo nemico naturale e il tempismo dei suoi rilasci in funzione delle popolazioni dell’ospite. In questo studio, larve di terza età, pupe e adulti farati sono stati esposti a 10 o 15 °C per 2, 4, 6 o 8 settimane al fine di valutare il tasso di emergenza e la capacità riproduttiva delle femmine adulte emerse. Lo stadio di sviluppo e la durata del trattamento sono stati gli unici fattori influenzanti lo sfarfallamento del parassitoide. Le larve sono state lo stadio con la più bassa sopravvivenza e le uniche emergenze sono state registrate solo dopo l’esposizione a 10 e 15 °C per due settimane. Per entrambe le temperature, la sopravvivenza del parassitoide esposto allo stadio pupale è stata significativamente inferiore al controllo e gli adulti sono emersi entro le sei e quattro settimane di esposizione quando conservati rispettivamente a 10 e 15 °C. Al contrario, i parassitoidi sono sopravvissuti e sfarfallati dallo stadio di adulto farato solo dopo massimo due settimane di esposizione, indipendentemente dalla temperatura, e con tassi di sopravvivenza simili al controllo. Per quanto riguarda la capacità riproduttiva delle femmine emerse dopo i vari trattamenti, l’esposizione dello stadio pupale a 10 °C per sei settimane ha ridotto significativamente sia la fertilità degli insetti testati che la percentuale di femmine nella progenie, quest’ultimo parametro ridotto anche in seguito a un’esposizione più breve a quattro settimane. Tuttavia, il numero limitato di adulti ottenuti non ha permesso tale tipo di valutazione nelle prove condotte sullo stadio larvale. I risultati ottenuti suggeriscono che una breve esposizione di G. brasiliensis come adulto farato a basse temperature permetterebbe di conservare con successo il parassitoide prima dei rilasci, ritardandone lo sfarfallamento e garantendo la fitness riproduttiva degli adulti ottenuti

Influenza degli stimoli vibrazionali sulla ricerca dell'ospite da parte di G1 Ganaspis cf. brasiliensis

Il parassitoide larvale G1 Ganaspis cf. brasiliensis (Hymenoptera: Figitidae) è stato selezionato come agente di controllo per il programma di controllo biologico classico di Drosophila suzukii (SWD). Il parassitoide mostra alta specificità e attacca 1° e 2° stadio larvale dell'ospite all'interno della frutta infestata. Mentre la ricerca dell'ospite a lungo e medio raggio è fortemente influenzata da stimoli chimici, il riconoscimento dell'ospite all'interno del suo microhabitat è possibilmente mediato da vibrazioni incidentali prodotte dalla larva in fase di sviluppo all'interno del frutto stesso. Abbiamo identificato e descritto tali vibrazioni mettendole in relazione al livello e tempo di infestazione. Abbiamo poi svolto delle prove comportamentali per investigare se G.brasiliensis utilizzi stimoli vibrazionali per riconoscere e discriminare il proprio ospite. Le risposte del parassitoide sono state analizzate considerando il tempo dedicato alla ricerca, ed il numero di inserzioni dell'ovipositore

Host stage preference, efficacy and fecundity of parasitoids attacking Drosophila suzukii in newly invaded areas

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) causes severe damage to certain fruit crops in both North America and Europe. This may be due, in part, to the absence of specialized natural enemies that suppress population outbreaks. We performed a series of experiments under controlled laboratory conditions in tandem with a field study to evaluate the presence and efficacy of natural enemies associated with this pest in Italian and western United States fruit production regions. Our study involved one larval parasitoid, Leptopilina heterotoma (Thomson) (Hymenoptera: Figitidae), and two pupal parasitoids, Pachycrepoideus vindemiae (Rondani) (Hymenoptera: Pteromalidae) and Trichopria drosophilae (Perkins) (Hymenoptera: Diapriidae). Three indices were used to describe host-parasitoid interactions: degree of infestation (DI), success rate of parasitism (SP) and total encapsulation rate (TER). Results confirmed that each of these parasitoid species can develop on certain populations of the pest. In addition, host stage preferences of the tested parasitoid populations, developmental parameters and lifetime fecundity of North American P. vindemiae are provided. Results are discussed with respect to differences in potential utilization of D. suzukii among the tested parasitoid species and regional populations.Keywords: Leptopilina heterotoma (Hymenoptera: Figitidae), Parasitoid, Trichopria drosophilae (Hymenoptera: Diapriidae), Biological control, Drosophila suzukii (Diptera: Drosophilidae), Pachycrepoideus vindemiae (Hymenoptera: Pteromalidae

Guidelines and framework to assess the feasibility of starting pre-emptive risk assessment of classical biological control agents

Non-native invasive arthropod species threaten biodiversity and food security worldwide, resulting in substantial economic, environmental, social and cultural costs. Classical biological control (CBC) is regarded as a cost-effective component of integrated pest management programmes to manage invasive arthropod pests sustainably. However, CBC programmes are traditionally conducted once a pest has established in a new environment, and invariably all research needed to achieve approval to release a biological control agent can take several years. During that time, adverse impacts of the pest accelerate. A pre-emptive biocontrol approach will provide the opportunity to develop CBC for invasive pests before they arrive in the country at risk of introduction and therefore enhance preparedness. A critical aspect of this approach is that risk assessment is carried out in advance of the arrival of the pest. Implementing pre-emptive biocontrol risk assessment means that natural enemies can be selected, screened in containment or abroad and potentially pre-approved prior to a pest establishing in the country at risk, thus improving CBC effectiveness. However, such an approach may not always be feasible. This contribution defines the fundamental prerequisites, principles, and objectives of pre-emptive biocontrol risk assessment. A set of guidelines and a decision framework were developed, which can be used to assess the feasibility of conducting a pre-emptive risk assessment for candidate biological control agents against high-risk arthropod pest

Seasonal occurrence of resident parasitoids associated with Drosophila suzukii in two small fruit production regions of Italy and the USA

For the first time we report the results of a survey to determine the presence, seasonal phenology and biological control status of indigenous parasitoid populations utilizing Drosophila suzukii (Matsumura) and Drosophila melanogaster Meigen (Diptera Drosophilidae) as hosts in Trento Province, Northern Italy, and the Willamette Valley, Oregon, USA. Larval and pupal parasitoids were sampled using sentinel traps baited with larvae of D. suzukii or D. melanogaster, or traps baited with fruit or yeast-based host substrates. Two generalist parasitoids, Pachycrepoideus vindemiae (Rondani) (Hymenoptera Pteromalidae) and Leptopilina heterotoma (Thomson) (Hymenoptera Figitidae) emerged from the sentinel traps in both regions, and a third generalist parasitoid, Trichopria drosophilae Perkins (Hymenoptera Diapriidae), was found in Italy. L. heterotoma was present during the early portion of the season in Italy while P. vindemiae was found throughout the growing season in both production regions. Low numbers of parasitoids relative to initial larval load in baits suggest a limited effect of indigenous parasitoids on D. suzukii in these two important fruit production regions. These findings highlight the need for improved biological control of D. suzukii through introduction or augmentation of specialist parasitoids from the native range of D. suzukii. This report provides baseline data on the current status of biological control of D. suzukii in Italy and Oregon.Keywords: Leptopilina heterotoma, biological control, Trichopria drosophilae, invasive pest, Pachycrepoideus vindemiae, parasitis

Drosophila suzukii population response to environment and management strategies

19openInternationalInternational coauthor/editorDrosophila suzukii causes economic damage to berry and stone fruit worldwide. Laboratory-generated datasets were standardized and combined on the basis of degree days (DD), using Gompertz and Cauchy curves for survival and reproduction. Eggs transitioned to larvae at 20.3 DD; larvae to pupae at 118.1 DD; and pupae to adults at 200 DD. All adults are expected to have died at 610 DD. Oviposition initiates at 210 DD and gradually increases to a maximum of 15 eggs per DD at 410 DD and subsequently decreases to zero at 610 DD. These data were used as the basis for a DD cohort-level population model. Laboratory survival under extreme temperatures when DD did not accumulate was described by a Gompertz curve based on calendar days. We determined that the initiation of the reproductive period of late dormant field-collected female D. suzukii ranged from 50 to 800 DD from January 1. This suggests that D. suzukii females can reproduce early in the season and are probably limited by availability of early host plants. Finally, we used the DD population model to examine hypothetical stage-specific mortality effects of IPM practices from insecticides and parasitoids at the field level. We found that adulticides applied during the early season will result in the largest comparative population decrease. It is clear from model outputs that parasitism levels comparable to those found in field studies may have a limited effect on population growth. Novel parasitoid guilds could therefore be improved and would be valuable for IPM of D. suzukii.openWiman, N.G.; Dalton, D.T.; Anfora, G.; Biondi, A.; Chiu, J.; Daane, K.M.; Gerdeman, B.; Gottardello, A.; Hamby, K.; Isaacs, R.; Grassi, A.; Ioriatti, C.; Lee, J.C.; Miller, B.; Rossi Stacconi, V.; Shearer, P.W.; Tanigoshi, L.; Wang, X.; Walton, V.M.Wiman, N.G.; Dalton, D.T.; Anfora, G.; Biondi, A.; Chiu, J.; Daane, K.M.; Gerdeman, B.; Gottardello, A.; Hamby, K.; Isaacs, R.; Grassi, A.; Ioriatti, C.; Lee, J.C.; Miller, B.; Rossi Stacconi, M.V.; Shearer, P.W.; Tanigoshi, L.; Wang, X.; Walton, V.M