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 nonmountainous 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Lepidoptera can cause several health issues in humans and domestic animals due to their setae, which are defensive adaptations that protect them from predators. The diversity of venomous Lepidoptera has been explored in several reviews starting from the first comprehensive attempt in 1984 by Kawamoto and Kumada (KK) who compiled a list of 228 species based on previous reviews; however, KK did not cite the original publications for listed species. In this review we validated and updated the KK table. The updated list of venomous Lepidoptera includes 5 superfamilies, 14 families, 208 genera, and 576 species, representing a two-fold increase for genera and 2.9-fold for species with respect to KK. The total number of species in the genera including at least one venomous species, which we argue is likely closer to the true number of venomous species, is 7 times higher (3,620). GBIF (Global Biodiversity Information Facility) occurrences for venomous species are 1-4 orders of magnitude higher than those of confamilial non-venomous species. The presence of venomous structures is independent of the relatedness of the clades or geographic region; venom is produced by many species of Zygaenoidea, Lasiocampoidea and Bombycoidea but only by some specialized groups in Papilionoidea and Noctuoidea. There are likely to be multiple evolutionary origins of venom within Lepidoptera, but the exact number is difficult to estimate. The knowledge gap between medical and natural history fields needs to be addressed with novel approaches to study ecology and toxicology. This review offers health practitioners a tool to better understand the origin of the reactions observed and to improve the identification of the causal agents. [ABSTRACT FROM AUTHOR]

Crops expressing insecticidal crystal proteins of Bacillus thuringiensis (Bt), often provide an opportunity for lower resistance selection toward synthetic pesticides due to reduced spraying frequency and the subsequent significant increase of natural enemies for the control of secondary pests. We would therefore expect declines in insecticide resistance levels. We analyzed patterns of resistance to insecticides used against cotton bollworm (CBW, Helicoverpa armigera) and cotton aphid (Aphis gossypii) in Australia and China in relation to landscape composition and pesticide applications. In both countries, insecticide resistance in H. armigera declined rapidly in the first 7-8 years of commercial Bt cotton farming, but the trend then reversed with resistance levels either higher or the same as before Bt cotton was commercialized. The susceptibility of A. gossypii to insecticides differs between China and Australia. In China, the relatively high resistance levels in aphids did not decline after introducing Bt cotton and in fact increased. In contrast, there was no clear trend of declining resistance levels in A. gossypii after the adoption of Bt cotton in established cotton growing areas in Australia. We conclude that the resistance in H. armigera was influenced by sprays in crops other than cotton in diverse cropping landscapes; in A. gossypii, resistance was driven by the insecticide use patterns within traditional cotton growing regions. Our study implies that the principals of rational landscape level resistance management for both target and secondary pests should be adopted when commercializing Bt cotton, to better account for the compatibility of Bt crops with IPM outside and within cotton industries. [ABSTRACT FROM AUTHOR]

The spatial distribution of an ecological subsidy can change local trophic cascades and create differences among locations; however, its contribution to shaping large-scale ecosystem functions is less well known. Here, using a multi-scale hierarchical design along a nitrogen input gradient, we assessed both local (within field level) and neighborhood (inter-field level) differences in soil nutrients and plant-arthropod communities to explain variation in landscape-scale crop productivity and biocontrol service. We found that the average importance of neighborhood factors increased, approached and even exceeded local factors in explaining the variance in the predator-to-aphid abundance ratio, wheat yield and parasitism rate. Compared to models with only local factors, both local and neighborhood factors when integrated into linear models explained an extra 67% and 18% of the variation in wheat yield and parasitism rate, respectively. Preserving the abundance and variability of biological resources on a specific spatial scale using targeted nitrogen subsidies may be a promising strategy for sustaining multiple ecosystem functions under intensified land use. [ABSTRACT FROM AUTHOR]

Given a decreasing area of Bt cotton in the Huanghe and Yangtze River valleys of China, the strategy of wide area management of cotton bollworm (Helicoverpa armigera) across Bt cotton crops needs to be revisited. We argue that the role of Bt cotton as a primary production crop can be transformed to that of a companion crop that attracts moths to oviposit and kills larvae, thereby protecting nearby primary crops such as soybean and peanut. In other words, Bt cotton could serve as a “dead-end-trap crop” (DETC) when planted surrounding or alongside the non-cotton crops in different landscapes. This is particularly practical and feasible for the small-holder farming systems in China. At the same time, such unsprayed DETC could foster larger populations of cotton aphids and become a source crop for predatory and parasitic beneficial insects of aphids. This, ‘killing of two birds with one stone’, or multi-functionality of DETC means they could serve as a way of reducing H. armigera at a landscape level and promote biological control services for various aphid pests in target crops. Having DETC across a landscape could also mitigate the development of H. armigera resistance to Bt toxins in the transgenic crop by minimizing Bt selection pressure. Such an approach may be more acceptable to farmers by reducing control costs and losses, benefit the environment health, enhance farmers wellbeing in China, and perhaps in other parts of the world. [ABSTRACT FROM AUTHOR]

In 1993, the apple buprestid, Agrilus mali Matsumura (Coleoptera: Buprestidae) native to northeast Asia, invaded the Yili River valley, Xinjiang Uyghur Autonomous Region, China. It is now widespread across 95% of wild apple forests (Malus sieversii (Ledeb.) Roem) in the region. This invasive species poses a major threat to wild apple populations serving as the key germplasm refuge for the ancestor of domestic apples across 6 countries in Central Eurasia. We first described the symptoms and damage caused by A. mali to wild apple trees, and then assessed the abundance of A. mali and tree damage under four different management strategies in three consecutive years (2016-2018): release of commercial biocontrol agents, aerial spraying of insecticide, aerial spraying/pruning, and establishment of fenced areas aiming to preserve understory vegetation and enhance natural pest control. The apple buprestid feeds on inner bark and preferentially damages the small branches (1-4 cm in diameter) located in the canopy 4-6 m above ground. The average fruit production declined from 90 kg to 10 kg per tree after the pest invasion. Pest abundance, as measured by counting damage scars, declined in sprayed areas. Fenced areas had higher pest abundance (damage). Fruit production in biological control and spraying/pruning areas increased slightly, while tree damage ranking declined over the years. Our results suggest that a combination of biological control and spraying/pruning may contribute to pest management of A. mali and resilience of wild apple forests in Central Eurasia. [ABSTRACT FROM AUTHOR]