Seasonal mite population distribution on Caryocar brasiliense trees in the Cerrado domain

Caryocar brasiliense Camb. (Malpighiales: Caryocaraceae) trees have a wide distribution in the Cerrado, and it is protected by federal laws. The need to monitor and understand pest damage to crops and forests is a major motivation for the study of population distribution. The mites (Acari) population distributions on C. brasiliense are unknown. We studied seasonal mite population distribution and their ecological indices on C. brasiliense trees in Cerrado areas during three years. Greatest number of Agistemus sp. (Stigmaeidae), Histiostoma sp. (Histiostomidae), Proctolaelaps sp. (Ascidae), and diversity and species richness on leaves of C. brasiliense occurred in the autumn; Tetranychus sp.1 (Tetranychidae) on leaves in the autumn and winter; Histiostoma sp., and Proctolaelaps sp. in fruits in the summer. No significant effect of season was observed in the abundance of Eutetranychus sp., Tetranychus sp.2 (Tetranychidae) and Acaridae. The populations of Acaridae, Eutetranychus sp., Proctolaelaps sp. and Tetranychus sp.1 negatively correlated with temperature. Proctolaelaps sp. and Tetranychus sp.1 correlated negatively with rainfall and Eutetranychus sp. and Proctolaelaps sp. positively with sunlight. The period with low rainfall and relative humidity increases the phytophagous mites and their predators, especially Agistemus sp.. The Tetranychus sp. and Histiostoma sp. species may become pests in C. brasiliense in the Cerrado domain.

Morphological and Biochemical Bases of Resistance of Some Groundnut Germplasms against Tobacco Caterpillar, Spodoptera litura (Fabricius) and Leaf Miner, Aproaerema modicella (Deventer)

A screening experiment of forty germplasm lines was conducted at College Farm, College of Agriculture, Rajendranagar, Hyderabad in rabi, 2019-20 and was laid in Randomized block design (RBD) having two replicates. Three germplasm lines viz., ICGV 16679 (13.71% leaf damage), ICGV 07222 (14.00% leaf damage) and ICGV 93468 (14.25% leaf damage) showed greater resistance than the resistant check, ICGV 86031 (15.04% leaf damage) against tobacco caterpillar and with respect to resistance against leaf miner, no germplasm line was found to be superior than the resistant check, ICGV 86031 (7.82% leaf damage). However, the germplasm line, ICGV 02266 (8.35% leaf damage) was next best to the resistant check. The various morphological and biochemical characters were recorded and correlated with insect pest damage and incidence to know their role in imparting resistance/susceptibility. Resistance to various insect pests in germplasm lines was due to significantly higher trichome density on leaf lamina, higher phenol and tannin content.

Evaluation of the impact of pre- and post-harvest maize handling practices on mycotoxin contamination on smallholder farms in Guatemala

Mycotoxins are secondary metabolites produced by fungi including Aspergillus and Fusarium that commonly contaminate crops, such as maize, resulting in economic losses and food insecurity. Mycotoxins can contaminate crops during pre- and post-harvest stages. Consumption of mycotoxin-contaminated foods has been linked to a variety of negative health outcomes including liver cancer, stunting, and neural tube defects. In countries such as Guatemala where maize constitutes a major portion of the diet, mycotoxins can be a significant contributor to disease burden. This review describes maize pre- and post-harvest practices in Guatemala that can lead to the development of mycotoxins and subsequent exposure to humans and animals, current information gaps, and opportunities for future research. There are specific challenges to minimising fungal growth and subsequent mycotoxin production during storage of maize in Guatemala, including reducing moisture content, minimising pest damage, and controlling temperature. Research on maize-handling practices that are associated with the greatest mycotoxin exposure in Guatemala is needed to prioritise allocation of resources and reduce exposure.

Weather based forewarning models for coffee berry borer and shot hole borer in Wayanad, Kerala

Pest damage due to coffee berry borer and shot hole borer in coffee plantations in Regional Coffee Research Station, Chundale and data on weather parameters were recorded during 1977 to 2007 (30 years). These long- term data on the pest damage and weather parameters were utilized to study the influence of weather variables on coffee berry and shot hole borer incidence with a view to develop weather based forewarning models for coffee berry borer and shot hole borer damage in Wayanad. The damage of coffee berry borer (CBB) was observed to be significant during January to March while the damage of shot hole borer (SHB) was spread during January to April and October to December. Highest percent damage of coffee berry borer and shot hole borer was observed during first fortnight of January. Maximum damage due to coffee berry borer was observed during 1982 and maximum damage due to shot hole borer was observed in 1994. Maximum temperature recorded during the first fortnight of January is predominant weather variable determining infestation of shot hole borer during first fortnight of January. Harvest and budding stages of the crop suffered heavy incidence of coffee berry borer and shot hole borer, respectively.

Deficit Water Irrigation in an Almond Orchard Can Reduce Pest Damage

Irrigated almond orchards in Spain are increasing in acreage, and it is pertinent to study the effect of deficit irrigation on the presence of pests, plant damage, and other arthropod communities. In an orchard examined from 2017 to 2020, arthropods and diseases were studied by visual sampling under two irrigation treatments (T1, control and T2, regulated deficit irrigation (RDI)). Univariate analysis showed no influence of irrigation on the aphid Hyalopterus amygdali (Blanchard) (Hemiptera: Aphididae) population and damage, but Tetranychus urticae Koch (Trombidiformes: Tetranychidae) damage on leaves was significantly less (50–60% reduction in damaged leaf area) in the T2 RDI treatment compared to the full irrigation T1 control in 2019 and 2020. Typhlocybinae (principal species Asymmetrasca decedens (Paoli) (Hemiptera: Cicadellidae)) population was also significantly lower under T2 RDI treatment. Chrysopidae and Phytoseiidae, important groups in the biological control of pests, were not affected by irrigation treatment. The most important diseases observed in the orchard were not, in general, affected by irrigation treatment. The multivariate principal response curves show significant differences between irrigation strategies in 2019 and 2020. In conclusion, irrigation schemes with restricted water use (such as T2 RDI) can help reduce the foliar damage of important pests and the abundance of other secondary pests in almond orchards.

The Potential of Intercropping for Multifunctional Crop Protection in Oilseed Rape (Brassica napus L.)

Oilseed rape (OSR; Brassica napus) is a globally important crop which is increasingly under pressure from pests, pathogens and weeds. We investigated the potential of achieving multifunctional crop protection benefits by intercropping oilseed rape with legumes. A field experiment was conducted in which winter oilseed rape was intercropped with the annual frost sensitive legumes berseem clover (Trifolium alexandrinum) or spring faba bean (Vicia faba), or with the winter grain legumes winter faba bean or winter peas (Pisum sativum). We tracked damage to winter oilseed rape by autumn and spring pests (slugs and insects), pathogens, weed biomass, as well as oilseed rape and intercrop yield in each treatment. Intercropping treatments resulted in pest damage that was equivalent or lower than in oilseed rape alone. Follow up field and lab assessments for the frost sensitive legume intercrops provided evidence for a reduction in autumn pest damage to OSR. Each legume intercrop had its own benefits and drawbacks in relation to pest, pathogen and weed suppression, suggesting that the plant species selected for intercropping with oilseed rape should be based on the pests, pathogens and weeds of greatest concern locally to achieve relevant multifunctional benefits. Our study provides a framework for further experiments in which the multifunctional effects of intercropping on pests, pathogens and weeds can be quantified.

Comparative Analysis of Coding and Non-Coding Features within Insect Tolerance Loci in Wheat with Their Homologs in Cereal Genomes

Food insecurity and malnutrition have reached critical levels with increased human population, climate fluctuations, water shortage; therefore, higher-yielding crops are in the spotlight of numerous studies. Abiotic factors affect the yield of staple food crops; among all, wheat stem sawfly (Cephus cinctus Norton) and orange wheat blossom midge (Sitodiplosis mosellana) are two of the most economically and agronomically harmful insect pests which cause yield loss in cereals, especially in wheat in North America. There is no effective strategy for suppressing this pest damage yet, and only the plants with intrinsic tolerance mechanisms such as solid stem phenotypes for WSS and antixenosis and/or antibiosis mechanisms for OWBM can limit damage. A major QTL and a causal gene for WSS resistance were previously identified in wheat, and 3 major QTLs and a causal gene for OWBM resistance. Here, we present a comparative analysis of coding and non-coding features of these loci of wheat across important cereal crops, barley, rye, oat, and rice. This research paves the way for our cloning and editing of additional WSS and OWBM tolerance gene(s), proteins, and metabolites.

Impact of Stand and Landscape Management on Forest Pest Damage

One promising approach to mitigate the negative impacts of insect pests in forests is to adapt forestry practices to create ecosystems that are more resistant and resilient to biotic disturbances. At the stand scale, local stand management practices often cause idiosyncratic effects on forest pests depending on the environmental context and the focal pest species. However, increasing tree diversity appears to be a general strategy for reducing pest damage across several forest types. At the landscape scale, increasing forest heterogeneity (e.g., intermixing different forest types and/or age classes) represents a promising frontier for improving forest resistance and resilience and for avoiding large-scale outbreaks. In addition to their greater resilience, heterogeneous forest landscapes frequently support a wide range of ecosystem functions and services. A challenge will be to develop cooperation and coordination among multiple actors at spatial scales that transcend historical practices in forest management. Expected final online publication date for the Annual Review of Entomology, Volume 67 is January 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

‘Resistance Mixtures’ Reduce Insect Herbivory in Strawberry (Fragaria vesca) Plantations

The transition toward more sustainable plant protection with reduced pesticide use is difficult, because there is no “silver bullet” available among nonchemical tools. Integrating several plant protection approaches may thus be needed for efficient pest management. Recently, increasing the genetic diversity of plantations via cultivar mixing has been proposed as a possible method to reduce pest damage. However, previous studies have not addressed either the relative efficiency of exploiting cultivar mixing and intrinsic plant herbivore resistance or the potential utility of combining these approaches to increase cropping security. Here, using a full factorial experiment with 60 woodland strawberry plots, we tested for the relative and combined effect of cultivar mixing and intrinsic plant resistance on herbivore damage and yield. The experiment comprised two levels of diversity (“high” with 10 varieties and “low” with two varieties) and three levels of resistance (“resistant” comprising only varieties intrinsically resistant against strawberry leaf beetle Galerucella tenella; “susceptible” with susceptible varieties only; and “resistance mixtures” with 50:50 mixtures of resistant and susceptible varieties). The experiment was carried out over two growing seasons. Use of resistant varieties either alone or intermixed with susceptible varieties in “resistance mixtures” reduced insect herbivory. Interestingly, resistant varieties not only reduced the mean damage in “resistance mixtures” by themselves being less damaged, but also protected intermixed susceptible varieties via associational resistance. The effect of higher genetic diversity was less evident, reducing herbivory only at the highest level of herbivore damage. In general, herbivory was lowest in plots with high diversity that included at least some resistant varieties and highest in low diversity plots consisting only of susceptible varieties. Despite this, no significant difference in yield (fruit biomass) was found, indicating that strawberry may be relatively tolerant. Our results demonstrate that combined use of high genetic diversity and resistant varieties can help reduce pest damage and provide a useful tool for sustainable food production. “Resistance mixtures” may be particularly useful for sensitive food crops where susceptible varieties are high yielding that could not be completely replaced by resistant ones.