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ABSTRACT Background Phosphorus (P) is an essential mineral element required in large quantities by plants. Globally, the availability of P in many soils is poor. Breeding crops that can acquire and utilise this limited resource with high efficiency is an important goal for agricultural sustainability in the future. The mapping and cloning of quantitative trait loci (QTLs) provides an effective tool in analyzing the genetic mechanisms underlying P efficiency and breeding P-efficient varieties. Scope This paper describes the QTL mapping of traits related to P efficiency which impact on shoot biomass or yield of crops in the past 20 years. It summarises the progress of studies on crop P-efficiency related QTLs and discusses the challenges for the cloning of QTLs. It proposes a scheme to develop crop genotypes with improved P efficiency. It also describes emerging methods, such as QTL-seq, genome-wide association analysis, and RNA-seq, that aid the rapid identification of P-efficiency related genes in crops. Conclusion Traits conferring P efficiency are heritable. Thus, it is feasible to incorporate phenotyping and selection for P efficiency in crop breeding programs. Identification of QTLs for target traits is a key step to enhancing the P efficiency of crops. Numerous QTLs have been identified that affect P efficiency in key crops, but few causal genes have been identified and breeding P-efficient crop varieties using marker-assisted selection (MAS) has not progressed far. The challenge now is to identify the specific genes controlling P-efficiency related traits. The availability of complete genome sequences for more crops, and the combination of conventional linkage mapping, association mapping, QTL-seq, transcriptomics and gene editing technologies can accelerate the cloning and confirmation of genes underlying QTL affecting P-efficiency related traits. Knowledge of these genes will be helpful in revealing the molecular mechanisms underlying P efficiency in crops, as well as providing the opportunity to improve crop P efficiency through MAS or gene manipulation.

The emerald ash borer, Agrilus planipennis, native to Asia is a devastating pest of ash in North America and European Russia. There are several parasitoids of A. planipennis recorded in Asia and North America, but none previously in Europe and European Russia. Eighty two specimens of the ectoparasitoid Spathius polonicus Niezabitowski (Hymenoptera: Braconidae: Doryctinae) (23 adults, 56 larvae and three pupae) were found in the remains of A. planipennis larvae at five localities in Moscow Province in October 2013 - May 2014. S. polonicus is rare but widely distributed and mainly a Western Palaearctic species. It seems that the level of parasitism could be relatively high: in nature, more than 50% of the last instar larvae of A. planipennis examined were killed by S. polonicus. We collected 24 live last instar larvae and prepupae and the remains of 30 last instar larvae of A. planipennis previously parasitized by S. polonicus. S. polonicus may be suitable for the biocontrol of A. planipennis both in Europe and North America, because it is a native of the temperate climate zone. The potential of this parasitoid for biological control needs special investigation.

Nesidiocoris tenuis (Reuter) (Hemiptera: Miridae) is an effective predator of pests of tomato crops and a promising biocontrol agent of Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) in the Mediterranean area. The aim of this study was to determine the numerical response of N. tenuis to different levels of abundance of T. absoluta and its potential for controlling it when infesting tomato crops. The effects of infesting plants with either 0.2 or 2 larvae of T. absoluta and releasing either 2 or 0 adults of N. tenuis per plant were assayed in a complete factorial randomised-block design with 3 repeats in 12 greenhouse compartments in southern Spain. The population dynamics of the moth was similar in all compartments, with and without N. tenuis, but T. absoluta reached a lower absolute peak density in compartments with N. tenuis (29.1 +/- 8.2 larvae per leaf) than in those without them (44.5 +/- 19.4 larvae per leaf). The peak numbers of larvae of T. absoluta did not differ on the plants initially infested with 0.2 or 2 larvae. Nesidiocoris tenuis reached a maximum of 1.9 +/- 0.43 and 3.0 +/- 0.4 individuals per leaf in compartments in which low and high numbers of T. absoluta were initially introduced, respectively. The yield of tomatoes was higher in the treatments with N. tenuis than in those without, but the percentage of damaged fruit (more than 50%) was similar. The slow numerical response of N. tenuis might have been due, among other things, to the poor establishment of this mirid due to the scarcity of prey. N. tenuis densities of about 0.2 individuals per leaf during the linear population growth phase of T. absoluta (0.5 to 3 larvae per leaf) did not prevent outbreaks.

In order to enhance the mass production of Musca domestica five aspects of its oviposition biology were analyzed. Oviposition substrate and the manner of its presentation, the composition of the diet of the adults, size of the pupae and numbers of flies in a cage were identified as critical. Females preferred to lay eggs on a substrate which was presented within a shelter and with increased linear edges against which the flies could oviposit. Different types of oviposition substrate resulted in comparable yields of eggs. The presence of an oviposition attractant (ammonia) in the manure was found to have a potentially positive effect on female fecundity. Egg yield increased when two protein sources (yeast and milk) were included in the adult diet. However, flies fed a mixture of sugar and yeast laid over 50% fewer eggs than those fed the same proportion of sugar and milk. The fecundity of flies decreased with the increase in the number of flies per cage, but the highest total number of eggs per cage was obtained with the highest density of flies (14.2 cubic cm per fly). The size of the pupae did not significantly affect egg production.

Muga silkworm is endemic to Assam and adjoining areas in North-Eastern India, and naturally produces golden silk. From time immemorial, many ethnic and tribal groups have produced muga silk. Muga silkworms are mostly wild unlike the mulberry silkworm, which is completely domesticated. The muga silkworm is a single species with little genetic variation among populations, survives harsh climatic conditions and is subject to various diseases, pests and predators. Due to the high incidence of disease and natural enemies, and variations in climatic conditions, the production of muga silk has recently declined dramatically. In order to improve the productivity of this silkworm it is important to have a better knowledge of both its host plants and biology. Lack of knowledge of its genetics and host plants is a major bottleneck. This paper reviews various aspects of muga silkworm culture, including the availability of different populations, and methods used to select for improvement in survival, cocoon yield, disease resistance, conservation and egg production.

The nutritive quality of aphids, conspecific and heterospecific eggs as food for ladybirds is a controversial issue. If ladybirds find aphids more palatable than eggs then they are more likely to efficiently exploit and be biocontrol agents of aphids. If eggs of conspecific or heterospecific ladybirds are more palatable than aphids these biocontrol agents may either impede aphid pest suppression or become a threat to other species of ladybirds. Thus, prior to formulating predatory guilds of ladybirds the nutritive quality of their eggs compared to that of the target aphid needs to be determined. In this regards, the present study evaluates the nutritive quality of an ad libitum supply of: (i) pea aphid, Acyrthosiphon pisum (Harris), (ii) conspecific eggs and (iii) heterospecific eggs as food for Coccinella septempunctata (L.) and Coccinella transversalis Fabricius (Coleoptera: Coccinellidae), by determining the stage specific predation and developmental attributes of these two ladybirds reared on these diets. The conversion efficiencies and growth rates of young (first, second and third) larvae of both species of ladybirds were higher than those of fourth instar larvae and the consumption rates of fourth instar were higher than those of young larvae when fed on the three diets. When fed aphids the pre-imaginal development was faster, the consumption rates, conversion efficiencies and growth rates higher, adults bigger and mortality lower than when fed on conspecific eggs. The larvae of C. septempunctata consumed and completed their development when fed eggs of C. transversalis but the first instar larvae of C. transversalis did not consume the eggs of C. septempunctata and died of starvation. The dominance of C. septempunctata over C. transversalis in agricultural fields may be due to it consuming and utilizing aphids more efficiently and as a consequence growing faster and suffering a lower mortality along with its ability to consume and complete its development on eggs of C. transversalis. Thus, both these predators may not continue to coexist as predators of the pea aphid in agricultural fields since C. septempunctata may become a greater threat to C. transversalis in the future.

Plant latex contains proteins and other components that defend plants against herbivorous insects. We determined the inhibitory activity of methanolic extracts of latex obtained from three species of plant: mulberry, Morus alba; jackfruit, Artocarpus heterophyllus; and weeping fig, Ficus benjamina, against trehalase in the red flour beetle, Tribolium castaneum. We also determined the changes that occurred throughout the life of the insect in the enzymatic activities of soluble and membrane-bound trehalase and the expression profiles of the genes encoding the two types of trehalase. Soluble trehalase activity was higher than membrane-bound trehalase activity in larvae and adults, whereas there was little difference in eggs, prepupae and pupae. The expression of the trehalases, TcTre-1 and TcTre-2, changed during insect development but did not coincide closely with changes in enzymatic activity, indicating that these changes did not necessarily depend on gene expression. All of three plant latices tested inhibited the activities of both the soluble and membrane-bound trehalase. At the gene expression level, these latices reduced the expression of TcTre-1 but not TcTre-2, indicating that the latices contain component(s) that selectively inhibit gene expression or at least differentially inhibit these two trehalase genes. The inhibition of trehalase activity resulted in a 140% increase in the concentration of trehalose in the beetle and a decrease in glucose concentration to 72% of the control. These findings show that the latices tested contain components that inhibit trehalase activity and TcTre-1 expression and thus, may contribute to the plants' defense against herbivorous insects.

The possibility of storing natural enemies at low temperatures is important for the mass production of biological control agents. We evaluated the effect of different periods of cold storage on immature mortality, mummy body mass, lifespan, reproduction and flight capacity of the parasitoid Praon volucre. One-day-old mummies of the aphid Macrosiphum euphorbiae containing pre-pupae of P. volucre were stored in a climatic chamber at 5 deg C and 70+/-10% RH in the dark for different periods of time (5, 10, 15 and 20 days). The control consisted of mummies kept at 22+/-1 deg C, 70+/-10% RH and a 12 h photophase. Percentage adult emergence, mummy body mass, flight capacity and number of eggs in the ovarioles of P. volucre females decreased with increase in the period of storage, while the longevity of females was only slightly affected. Fat content of mummies, percentage of parasitized aphids and survival-of progeny to emergence decreased with increase in the period of storage. Storage of P. volucre pre-pupae for up to 5 days at 5 deg C did not affect any of the above mentioned parameters. The fact that P. volucre pre-pupae can be stored for 5 days without loss of quality and for 10 days with only a slight loss facilitates the planning of mass production and shipment.

Chrysoperla sinica is a polyphagous natural enemy attacking several pests on various crops in China. We investigated the effect of feeding it different species of prey on its pre-imaginal development, survival, adult longevity and fecundity under laboratory conditions. The prey species tested were nymphs of Aphis glycines, Aphis gossypii, Myzus persicae, Rhopalosiphum maidis and Aphis craccivora, and eggs of Corcyra cephalonica. None of these species of prey affected the pre-imaginal survival or percentage survival of the eggs of the predator. However, eggs of C. cephalonica and nymphs of M. persicae and A. glycines were the best of the prey species tested. When fed on these species, the pre-imaginal developmental period of C. sinica was shorter and its adult longevity, fecundity and percentage survival greater than when fed the other species of prey. In contrast, when fed nymphs of A. craccivora, the pre-imaginal development period was longer, adult longevity shorter and fecundity lower.

Little is known about the life cycle of Rhembobius parasitoids (Hymenoptera: Ichneumonidae). Known host records are mainly from saprophagous species of hoverflies of the tribe Eristalini (Diptera: Syrphidae), whose larvae develop in a wide range of aquatic and semi-aquatic breeding sites that are rich in microbial decay. We present an account of the biology and important details of the life cycle of the pupal parasitoid R. quadrispinus in both natural and controlled conditions. Host suitability, the influence of host pupal age and age of the female parasitoid on her production of progeny was evaluated in laboratory tests. Our results showed that the percentage of pupae of E. tenax that were parasitized by R. quadrispinus decreased as pupae matured, and the optimal age for successful parasitism ranged from 1 to 3 days. This biological information could be useful in the biological control of anthropophilic saprophagous eristalines that can act as potential mechanical vectors of pathogens on farms.