Search

Understanding how landscape composition and configuration drive the dynamics of pests and their various natural enemies is crucial to enhance biological control services (biocontrol). Geographic variability in landscape effects prompts questions about whether this is due to genuine differences or methodological differences among studies, given that most studies are conducted in a single region. This study investigated how the ecological function of parasitoids and predators responds to landscape traits in three regions encompassing an agriculture intensification gradient. The effects of landscape structure and configuration differed among regions and natural enemies. Non-crop habitats increased the abundance of parasitoids only in two less intensified regions presumably due to insufficient amount of non-crop habitats in the intensified region (typically < 10%). Nevertheless, their biological control efficiency (BCE) was consistently increased by non-crop habitats across regions. Higher maize proportion increased predator abundance and their BCE in the two non-mountainous regions. The value of maize as a source habitat for predators may have been limited in the mountainous region due to the lower aphid abundances there. Edge density positively affected abundances of predators and parasitoids, but only positively increased the BCE of all natural enemies combined. Inconsistent regional responses to the same landscape variables suggest that a uniform integrated pest management strategy for alfalfa is impractical. However, increasing edge density should be a useful first step for supporting diverse natural enemy communities and their biocontrol potential.

The invasive apple wood borer Agrilus mali Matsumura (Coleoptera: Buprestidae) threatens the viability of wild apple forests in Xinjiang, China, imperiling the preservation of apple germplasm resources in Central Eurasia. Pruning infested branches can reduce the likelihood of outbreaks of various pests and associated damage, but its efficacy and feasibility for managing A. mali has not been well-studied. Therefore, we examined the efficacy of pruning at three different times of the year in commercial orchards in 2018 and 2019. We evaluated the efficacy of pruning for longer-term sustainable management of A. mali in wild apple forests over a five-year period from 2016–2019. Autumn pruning resulted in mortality of all immature A. mali in pruned branches, increased flowering in individual trees, and a significant reduction in both pest density and tree damage on the landscape. Simulation modeling showed that a single well-timed pruning treatment could maintain low pest density for at least 6–10 years. Recurring pruning schedules may be an effective long-term management tool, suppressing A. mali populations in wild apple forests and facilitating ecosystem recovery. This practical tactic could prove instrumental in managing A. mali and sustaining ecosystem health, particularly in the face of future invasions in wild apple forests in central Eurasia.

Cannibalism, an act of killing and consuming conspecific individuals, is a common behavior among various insect taxa. This study investigated the effects of food limitation and larval health status on cannibalistic behavior in the South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae), a devastating insect pest on solanaceous crops. In “no-choice” trials, where either a healthy versus weak conspecific larva was provided, T. absoluta larvae exhibited a significantly higher cannibalism rate toward weak conspecific individuals compared with healthy ones. This pattern was further confirmed in “choice” trials where T. absoluta larvae significantly preferred to consume weak larvae to healthy ones when both targets were supplied. When plant food was supplied as an alternative to a healthy or a weak conspecific larva, cannibalism was observed only when weak conspecific individuals were available, despite a significant preference for tomato leaflets. Therefore, cannibalism in T. absoluta is largely opportunistic and is significantly influenced by plant food limitation and larval health status. These findings enhance our understanding of conspecific interactions in herbivorous insects.

Tuta absoluta (Lepidoptera: Gelechiidae) originates from the South American tropics but has become a major invasive pest of tomato and other Solanaceae crops worldwide. Agricultural protected facilities (APFs) such as greenhouses and plastic tunnels may provide thermal conditions that allow the survival of T. absoluta in temperate zones with cold winters. In this study, a CLIMEX model was used to investigate the dual effects of increasing use of APFs and climate warming on the potential distribution and seasonal dynamics of T. absoluta in China. Our model showed that the northern boundary for year-round population persistence in China, ignoring APFs, was approximately 30°N, covering about 21% of China’s area suitable under current climate. The modelled suitable area increased to 31% and northern boundary for year-round population persistence shifted to 40°N in 2080 under global warming. When APF refuges are included, the potential suitable area was 78% under the current climate and 79% under global warming. This suggests that, in the future, the increasing use of APFs will increase the areas at risk of T. absoluta invasion significantly more than global warming because APFs effectively protect T. absoluta from harsh northern winters. In addition, vegetable production in surrounding open fields will be at risk of invasion during milder seasons when APFs are opened and T. absoluta can disperse. Therefore, the micro-climate of APFs should be considered as part of the invasion process, and Integrated Pest Management should be simultaneously implemented inside and outside APFs for the rational management T. absoluta. Keywords

Background: The globose scale (GS), Sphaerolecanium prunastri(Boyer de Fonscolombe) (Hemiptera: Coccoidea), has invaded wild apricot forests in their native range in Central Eurasia threatening the ancestral germplasm resource. Biological control efficacy of the harlequin ladybird, Harmonia axyridis(Pallas, 1773) (Coleoptera: Coccinellidae) against the globose scale was assessed in laboratory and field experiments. Results: In the laboratory, Harmonia axyridishas a high feeding capacity on GS with numbers consumed daily increasing with temperature (15, 20, 25, 30, 35 °C), reaching an upper asymptote of 160–200 scales per day. In field cage experiments, efficacy of biological control (EBC) against first instar (49–99%) and second instar nymphs (20–80%) increased with GS density. When ants were present, control efficiency was reduced by 10–15%. In open-field experiments without cages, EBC was comparatively lower regardless of duration and how H. axyridiswere released whether as adults, eggs cards or a mixture of adults and eggs cards. Conclusions: In the long term, biological control with this ladybird predator could be considered as part of an IPM program package that includes banning or delaying mowing grass and understory plants in the forests that offer pollen and nectar for natural enemies.

Host plants indirectly affect parasitoid life-history traits via parasitoid hosts. Here, we evaluated the life-history traits of the parasitoid Aphelinus varipesemerging from the green peach aphid, Myzus persicae(Hemiptera: Aphididae), feeding on five commercially important vegetables. The results showed that A. varipesfed upon and parasitized maximum number of aphids grown on chili pepper, and least on cabbage. The emergence rate was the highest on chili pepper (100%) and lowest on crown daisy (71.1 ± 2.17%). Aphelinus varipesdeveloped fastest on hosts reared on chili pepper (12.9 ± 0.02 d) and slowest on aphids reared on cabbage (14.1 ± 0.02 d). The body weight and body size of emerging wasp parasitoids and aphids were greatest on chili pepper and lowest on cabbage. Aphid body size positively affect parasitism, development time, and body size of the parasitoid. In conclusion, our results showed that the parasitoid A. varipeshad variable life-history parameters, depending on the host plant species and host body size. The effects of host plant species on performance of M. persicaeand its parasitoid A. varipesare discussed, along with the potential of using A. varipesto control M. persicaeon different plants.

Native to Asia, the spotted lanternfly, Lycorma delicatula(White), is an emerging pest of many commercially important plants in Korea, Japan, and the United States. Determining its potential distribution is important for proactive measures to protect commercially important commodities. The objective of this study was to assess the establishment risk of L. delicatulaglobally and in the United States using the ecological niche model MAXENT, with a focus on Washington State (WA), where large fruit industries exist. The MAXENT model predicted highly suitable areas for L. delicatulain Asia, Oceania, South America, North America, Africa, and Europe, but also predicted that tropical habitats are not suitable for its establishment, contrary to published information. Within the United States, the MAXENT model predicted that L. delicatulacan establish in most of New England and the mid-Atlantic states, the central United States and the Pacific Coast states, including WA. If introduced, L. delicatulais likely to establish in fruit-growing regions of the Pacific Northwest. The most important environmental variables for predicting the potential distribution of L. delicatulawere mean temperature of driest quarter, elevation, degree-days with a lower developmental threshold value of 11°C, isothermality, and precipitation of coldest quarter. Results of this study can be used by regulatory agencies to guide L. delicatulasurveys and prioritize management interventions for this pest.