Carmen S. S. Pires

Mutually beneficial pollinator diversity and crop yield outcomes in small and large farms

More-diverse pollinators improve crop yields It is known that increased pollinator diversity can improve the yield of agricultural crops. However, how best to both produce food and maintain diversity is still debated. Garibaldi et al. show that on small farms, which provide food for the most vulnerable populations globally, pollinator diversity can significantly increase productivity. Thus, the management of crops and surrounding areas for ecological health is likely to benefit both wild pollinator populations and farmers. Science, this issue p. 388 A large international data set confirms that increased diversity of wild pollinators increases crop yields. Ecological intensification, or the improvement of crop yield through enhancement of biodiversity, may be a sustainable pathway toward greater food supplies. Such sustainable increases may be especially important for the 2 billion people reliant on small farms, many of which are undernourished, yet we know little about the efficacy of this approach. Using a coordinated protocol across regions and crops, we quantify to what degree enhancing pollinator density and richness can improve yields on 344 fields from 33 pollinator-dependent crop systems in small and large farms from Africa, Asia, and Latin America. For fields less than 2 hectares, we found that yield gaps could be closed by a median of 24% through higher flower-visitor density. For larger fields, such benefits only occurred at high flower-visitor richness. Worldwide, our study demonstrates that ecological intensification can create synchronous biodiversity and yield outcomes.

Induced volatiles in soybean and pigeon pea plants artificially infested with the neotropical brown stink bug, Euschistus heros, and their effect on the egg parasitoid, Telenomus podisi

Herbivory is known to increase the emission of volatiles, which attract natural enemies to herbivore‐damaged plants in laboratory and agricultural systems. We report on signalling through volatiles induced by Euschistus heros (F.) (Heteroptera: Pentatomidae) in two legumes that influence the attraction and retention of the egg parasitoid Telenomus podisi (Ashmead) (Hymenoptera: Scelionidae). Air‐borne extracts obtained from two host plants of E. heros, soybean, Glycine max, and pigeon pea, Cajanus cajan (Leguminosae), produce a different blend of emitted volatiles when attacked by adult males or females and nymphs of the pest species, compared with the undamaged plants. The same results were obtained when the plants were treated with extracted saliva of E. heros which had been mechanically introduced into the plants. This indicates that some substance in the saliva contributed to the release of the volatiles. Bioassays in a Y‐tube olfactometer with female T. podisi and treated plants confirmed the significant preference of the egg parasitoid for plants attacked by either males, females, or fourth instar nymphs of the pest species. On the other hand, volatile extracts obtained from soybean subjected to the velvetbean caterpillar, Anticarsia gemmatalis, a non‐host species for T. podisi, showed a different blend of volatiles compared to those obtained from plants subjected to E. heros. Additionally, the volatiles obtained from this plant–host complex were not attractive to T. podisi. These results indicate that E. heros causes an increase in the emission of specific plant volatiles, and that the induction is possibly caused by an elicitor present in the pest saliva. The possibility that these plant volatiles play an important role in the attraction and retention of the egg parasitoid T. podisi is discussed.

Monitoring the Neotropical brown stink bug Euschistus heros (F.) (Hemiptera: Pentatomidae) with pheromone‐baited traps in soybean fields

The effectiveness of the synthetic sex pheromone of the Neotropical brown stink bug, Euschistus heros, was evaluated both in laboratory and in field assays. Lures loaded with 1 mg of methyl 2,6,10‐trimethyltridecanoate (TMTD) continuously attracted female bugs for more than 30 days to pheromone‐baited traps in field trials. The pheromone‐baited traps were effective in field tests even at low bug population densities, as compared with the usual monitoring technique, shake cloth sampling. Traps around borders or in the centre of soybean fields caught similar numbers of bugs. Trap captures showed a positive relationship with field populations, as monitored with the shake cloth technique, during the reproductive phase of the soybean crop, i.e. from the R1–R5 developmental stage (pod formation to pod fill). The physiological state of the trapped migrating insects was determined. The first insects arriving in the field had fewer eggs in the reproductive tract compared to later arrivals. Some cross‐attraction was also observed, with Piezodorus guildinii and Edessa meditabunda also being caught in pheromone‐baited traps, suggesting that these insects respond to the sex pheromone or to the defensive compounds released by E. heros captured in traps. In brief, the results showed that traps baited with 1 mg of the sex pheromone efficiently caught bugs, that the lures lasted for more than 1 month under field conditions and that placement of traps around the borders of the crop area was as effective as placement inside the crop area. Border‐placed traps were effective at a density of one trap every 200 m.

Inter and intra-guild interactions in egg parasitoid species of the soybean stink bug complex

Abstract – The objective of this research was to evaluate the parasitism behavior of Telenomus podisiAshmead, Trissolcus basalis (Wollaston) e Trissolcus urichi Crawford (Hymenoptera: Scelionidae) oneggs of Nezara viridula L., Euschistus heros F., Piezodorus guildinii Westwood and Acrosternumaseadum Rolston (Heteroptera: Pentatomidae), in no choice and multiple choice experiments. For allparasitoid species, the results demonstrated the existence of a main host species that maximizes thereproductive success. The competitive interactions among the parasitoid species were investigated inexperiments of sequential and simultaneous release of different combinations of parasitoid pairs on thehosts N. viridula, E. heros and A. aseadum. Exploitative competition was observed for egg batches atthe genus level ( Telenomus vs. Trissolcus) and interference competition at the species level ( T. basalisvs. T. urichi). Trissolcus urichi was the most aggressive species, interfering with the parasitism ofT. basalis. Generally, T. basalis showed an opportunistic behavior trying to parasitise eggs after T. urichihad abandoned the egg batch. The selection of parasitoid species for use in augmentative biologicalcontrol programs should take into account the diversity of pentatomids present in soybean in additionto the interactions among the different species of parasitoids.Index terms: parasitism, host-parasite relations, biological competition, pest control methods.Interacoes inter-guilda e intra-guilda entre especies de parasitoides de ovosque atacam o complexo de percevejos da sojaResumo – O objetivo desta pesquisa foi avaliar o comportamento de parasitismo de Telenomus podisiAshmead, Trissolcus basalis (Wollaston) e Trissolcus urichi Crawford (Hymenoptera: Scelionidae)em ovos de Nezara viridula L., Euschistus heros F., Piezodorus guildinii Westwood e Acrosternumaseadum Rolston (Heteroptera: Pentatomidae), em experimentos de multipla escolha e sem escolha dehospedeiros. Todas as especies de parasitoides testadas demonstraram possuir um hospedeiro quemaximizou a sua capacidade reprodutiva. As interacoes competitivas entre especies de parasitoidesforam investigadas mediante experimentos de liberacao sequencial e simultânea de diferentescombinacoes de pares de especies de parasitoides em N. viridula, E. heros e A. aseadum. Competicaopor exploracao foi observada a nivel de genero ( Telenomus vs. Trissolcus) e competicao por interferenciaa nivel de especie (T. basalis vs. T. urichi). A especie mais agressiva foi T. urichi, interferindo noparasitismo de T. basalis. Geralmente, T. basalis apresentou um comportamento oportunista tentandoparasitar os ovos apos T. urichi ter abandonado os lotes de ovos. A selecao de especies de parasitoidespara uso em programas de controle biologico aumentativo deve considerar a diversidade depentatomideos presentes na soja, alem das interacoes entre as especies de parasitoides que serao liberadas.Termos para indexacao: parasitismo, relacao parasita-hospedeiro, competicao biologica, metodos decombate as pragas.

Patterns of Host Plant Growth and Attack and Establishment of Gall-Inducing Wasp (Hymenoptera: Cynipidae)

Abstract We examined the effect of shoot size distribution within plants and different stage of host plant development on the pattern of attack of Andricus sp. on gambel oak, Quercus gambelli Nuttall. The gall-inducing wasp preferred large diameter shoots to small ones in 2 populations of host plant. Attack on larger shoots was significantly nonrandom and occurred even though these shoots were relatively scarce in the shoot population. Large shoots accounted for only 5.51 and 12.72% of the total shoots in an urban and forest site, respectively. The percentage of attack on shoots in the largest shoot diameter class was 10.53 and 48.74% in the urban and forest site, respectively. Gall density decreased with maturity of the host plant and was 3 times higher on juvenile plants compared with mature plants. The distribution of attack in relation to plant age was not related to changes in shoot size with the age of the plants. Gambel oak may become resistant to gall formation with increasing age. Survival was 33.72% higher on large shoots (83.72%) compared with small shoots (50.00%). Larval survival did not change with plant age among host plants. The pattern of attack in relation to shoot size suggests that Andricus sp. prefer to oviposit on large shoots in which larval performance was highest. Andricus sp. might show a flexible oviposition preference hierarchy for shoot lengths. Females attacked the longest shoots available rather than showing a fixed preference for specific shoot lengths.

Ten policies for pollinators

What governments can do to safeguard pollination services Earlier this year, the first global thematic assessment from the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) evaluated the state of knowledge about pollinators and pollination (1, 2). It confirmed evidence of large-scale wild pollinator declines in northwest Europe and North America and identified data shortfalls and an urgent need for monitoring elsewhere in the world. With high-level political commitments to support pollinators in the United States (3), the United Kingdom (4), and France (5); encouragement from the Convention on Biological Diversitys (CBDs) scientific advice body (6); and the issue on the agenda for next months Conference of the Parties to the CBD, we see a chance for global-scale policy change. We extend beyond the IPBES report, which we helped to write, and suggest 10 policies that governments should seriously consider to protect pollinators and secure pollination services. Our suggestions are not the only available responses but are those we consider most likely to succeed, because of synergy with international policy objectives and strategies or formulation of international policy creating opportunities for change. We make these suggestions as independent scientists and not on behalf of IPBES.

Detection and decay rates of prey and prey symbionts in the gut of a predator through metagenomics

DNA methods are useful to identify ingested prey items from the gut of predators, but reliable detection is hampered by low amounts of degraded DNA. PCR‐based methods can retrieve minute amounts of starting material but suffer from amplification biases and cross‐reactions with the predator and related species genomes. Here, we use PCR‐free direct shotgun sequencing of total DNA isolated from the gut of the harlequin ladybird Harmonia axyridis at five time points after feeding on a single pea aphid Acyrthosiphon pisum. Sequence reads were matched to three reference databases: Insecta mitogenomes of 587 species, including H. axyridis sequenced here; A. pisum nuclear genome scaffolds; and scaffolds and complete genomes of 13 potential bacterial symbionts. Immediately after feeding, multicopy mtDNA of A. pisum was detected in tens of reads, while hundreds of matches to nuclear scaffolds were detected. Aphid nuclear DNA and mtDNA decayed at similar rates (0.281 and 0.11 h−1 respectively), and the detectability periods were 32.7 and 23.1 h. Metagenomic sequencing also revealed thousands of reads of the obligate Buchnera aphidicola and facultative Regiella insecticola aphid symbionts, which showed exponential decay rates significantly faster than aphid DNA (0.694 and 0.80 h−1, respectively). However, the facultative aphid symbionts Hamiltonella defensa, Arsenophonus spp. and Serratia symbiotica showed an unexpected temporary increase in population size by 1–2 orders of magnitude in the predator guts before declining. Metagenomics is a powerful tool that can reveal complex relationships and the dynamics of interactions among predators, prey and their symbionts.

Alternative food sources and overwintering feeding behavior of the boll weevil, Anthonomus grandis boheman (coleoptera: curculionidae) underthe tropical conditions of central Brazil

The boll weevil causes serious damage to the cotton crop in South America. Several studies have been published on this pest, but its phenology and behavior under the tropical conditions prevailing in Brazil are not well-known. In this study the feeding behavior and main food sources of adult boll weevils throughout the year in Central Brazil was investigated. The digestive tract contents of insects captured in pheromone traps in two cotton fields and two areas of native vegetation (gallery forest and cerrado sensu stricto) were analyzed. The insect was captured all through the year only in the cerrado. It fed on pollen of 19 different plant families, on Pteridophyta and fungi spores and algae cysts. Simpson Index test showed that the cerrado provided greater diversity of pollen sources. In the beginning of the cotton cycle, the plant families used for pollen feeding were varied: in cotton area 1, the weevil fed on Poaceae(50%), Malvaceae and Smilacaceae (25% each); in cotton area 2 the pollen sources were Malvaceae (50%), Asteraceae (25%) and Fabaceae and Clusiaceae (25% each); in the cerrado they were Chenopodiaceae (67%) and Scheuchzeriaceae (33%). No weevils were collected in the gallery forest in this period. After cotton was harvested, the family Smilacaceae was predominant among the food plants exploited in all the study areas. These results help to explain the survivorship of adult boll weevil during cotton fallow season in Central Brazil and they are discussed in the context of behavioral adaptations to the prevailing tropical environmental conditions.

The Environmental Effects of Genetically Modified Crops Resistant to Insects

Transgenic crops are currently being cultivated on a commercial scale in many countries. The area devoted to transgenic pest resistant varieties worldwide reached 13 million hectares in 2001. These varieties offer valuable benefits but also pose potential risks. Assessments of their impact on the environment are conducted before they are approved for commercial use, as required by the regulatory biosafety frameworks. In this review, we discuss the potential ecological consequences of the commercial use in agriculture of genetically modified insect resistant crops. We also discuss the impacts caused by the change in agricultural practices, and attempt to identify gaps and possible opportunities for research, considering this new technological tool. We based our analysis and comments on the current knowledge of the risks and benefits of these genetically modified insect resistant crops, within the context of traditional insect management strategies.

Dry-Season Embryonic Dormancy in Deois flavopicta (Homoptera: Cercopidae): Roles of Temperature and Moisture in Nature

Abstract A field-based experimental study examined the roles of temperature and moisture in the dry-season embryonic dormancy and postdormancy hatching of the spittlebug Deois flavopicta Stål from Brazil’s dry interior region. The results show that dormancy consists of two discrete parts: an initial period of diapause that persists from April to the beginning of July, followed by a period of postdiapause quiescence that prevails until the rainy season begins (usually October). Low temperatures during the early part of the diapause period accelerates diapause development, whereas contact with liquid water determines the timing of postdiapause hatching. Soil temperatures during June and July and the relative humidity of the soil during August and September strongly affect overwintering survival and thus are important in determining the size of the nymphal population after dormancy. The findings indicate that, like hibernation and aestivation in temperate-zone insects, dry-season dormancy in tropical insects is a dynamic state that is influenced by seasonal changes in key environmental factors.