Aspects of the biology and ecology of Acyrthosiphon kondoi shinji (Homoptera: Aphididae): a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Biology at Massey University

The biology and ecology of the blue-green lucerne aphid, Acyrthosiphon kondoi Shinji, was studied in the Palmerston North area for one year. Observations on the morphology of the developmental stages and morphs of A. kondoi are presented. Winter and spring peaks in the A. kondoi numbers occurred and the aphid can survive on lucerne all year round. The aphid colonies undergo a population cycle involving a population build up, high numbers, a decline in numbers, and a period of low numbers which persists until the next population build up. The stage of the cycle is apparent from the pattern of dispersion of the aphids on the plant and the number of alates present. A. kondoi appears to be continuously viviparous and parthenogenetic. throughout the year, as no sexual forms were found. High numbers of A. kondoi migrate by flying. A distinct spring peak in flight was observed with periods of lesser flight at other times. Some synchrony between the periods of flight and the number of aphids and alates on the plants was observed. Factors controlling the A. kondoi population were studied. The predators, and an entomophthorous fungi which attacked A. kondoi were identified, but no evidence of parasitism of A. kondoi in the field was observed. The predators did not prevent the spring population peak of A. kondoi, because of the low predator numbers and their poor synchronisation with the aphid population. Predator exclusion cage studies indicated that predators, especially Nab is maoricus. prevented a summer-autumn A. kondoi population peak. N. maoricus consumed on average 11.25 A. kondoi per day in the laboratory. The state of host plant growth is important in the occurrence of population cycles, and lucerne management practices can affect this considerably. Growing lucerne appears most suitable. Flowering of lucerne is not unfavourable to A. kondoi. A decline in the plant condition is partially involved in the population decline. Cycles of the A. kondoi population occur independently of climate, though the maximum number of aphids reached in each cycle is probably dependent on climatic factors. Local, extreme weather conditions nay temporarily affect A. kondoi numbers. The population cycle involves self-regulation and can probably occur independently of extrinsic factors. It involves a rise and fall in the fecundity and reproductive rate,and the production of increasing numbers of alates as the cycle progresses. These changes could account for a considerable part of the population decline observed in a population cycle

Local and landscape effects of field margins on aerially dispersing beneficial insects and spiders

Field margins were implemented in UK agri-environment schemes with the aim to increase farmland biodiversity. Recently aerially dispersing aphid enemies have been shown to provide the majority of aphid control in winter wheat fields but there is a lack of research conducted on the aerial predator guild. This thesis examines the effect field margins have on aphid predators at the single field scale, the landscape scale and, using results from a marking study, examines the direct use of a pollen and nectar rich field margin by Episyrphus balteatus. At the single field scale, field margins had a positive effect of the numbers of Cantharidae, Empididae, Linyphiidae and Tachyporus spp. in fields with sown margins compared to those without during wheat growth and total aphid predator numbers were significantly higher in fields with margin surrounds in early May but not later in the year. At the landscape scale, results from twelve winter wheat fields with varying densities of surrounding field margins showed predatory Tachyporus spp. to exhibit a positive correlation at scales above 500m radius and Cantharidae to exhibit a negative correlation at local scales. Implications for field margins exerting both positive and negative influences on the presence of aerially dispersing aphid predators in winter wheat fields are discussed. A marking study using rubidium chloride proved direct utilisation of a pollen and nectar rich field margin by the Syrphid Episyrphus balteatus, and the traps used in this study also highlighted the association in distributions between Empididae and cereal aphids. Overall it was concluded that the presence of field margins does have an effect on the spatial and temporal distributions of some aerially dispersing aphid predators, but the response of each predator group varies depending on numerous interlinking components of their life history and directions for future research are discussed

Early-season predation on aphids by winter-active spiders in apple orchards revealed by diagnostic PCR

Aphids are major pests in apple orchards, debilitating the crop and spreading disease. We investigated whether early-season predation by canopy spiders may be effectively controlling aphid numbers in three organic orchards. For this purpose, we monitored the aphid population dynamics from the winter eggs to colony stages and compared this to spider abundances and rates of predation on aphids detected by diagnostic polymerase chain reaction. For the latter, we applied existing general aphid primers. We found that spiders ate colony fundatrices and that aphid numbers were negatively related to spider abundance. Spiders were the main active predators within the orchards when the first colony fundatrices were present, indicating their importance in the early control of aphid populations

Understanding earwig phenology in top fruit orchards

Earwigs, Forficula auricularia, are key generalist predators to a variety of orchard pests. However, numbers of earwigs have declined in both organic and IPM orchards in recent years. Both Integrated and Organic fruit growers have tried to re-establish earwig populations, thus far with little success. To understand earwig population dynamics and to find measures to increase natural orchard populations, we conducted a detailed phenological survey of earwigs in orchards. Earwigs were sampled while sheltering during daytime in artificial refuges. They move into the trees from the third nymph stage onwards. In most orchards, a small second brood is produced in summer, and this has a positive impact on population size in fall. We see only minor differences in phenology between apple and pear orchards, mainly caused by differences in alternative hiding places. Earwigs show an inexplicable reduction in numbers at the timing of moulting into adults. When earwig phenology is correlated with pest phenology in apple and pear, its use for pest control of major pests is clear

\u3ci\u3eHippodamia Variegata\u3c/i\u3e (Goeze) (Coleoptera: Coccinellidae) Detected in Michigan Soybean Fields

Since its initial detection near Montreal, Canada in 1984, the variegated lady beetle Hippodamia variegata (Goeze) (Coleoptera:Coccinellidae) has spread throughout the northeastern United States. In 2005, this immigrant Old World species was detected in Michigan for the first time. Twenty-nine adults were found in soybean fields in 4 counties: Ingham, Gratiot, Kalamazoo, and Saginaw.The first individuals were found in Gratiot County on 22 June 2005; we continued to detect individuals until 18 Aug 2005 (2 individuals collected in Saginaw Co.) when sampling ended. Prior to this study, H. variegata had not been known to prey on the soybean aphid, Aphis glycines Matsumura (Homoptera: Aphididae). The establishment of soybean aphid throughout the north-central U.S. may aid the spread of H. variegata throughout the region

AN INTRASEASONAL BIOECONOMIC MODEL OF PLRV NET NECROSIS

A bioeconomic model is developed as an IPM planning tool to combat PLRV net necrosis in the PNW potato industry. Environmental/biological and production processes are linked to marketing activities using discrete time control. We find that pesticides can be optimally timed to reduce applications and still protect against net necrosis.Crop Production/Industries, Environmental Economics and Policy,

Rethinking Ecosystem Services from an Intermediate Product Perspective

The Earth's ecosystems provide myriad goods and services that are essential to human wellbeing. This paper offers a typology of ecosystem services that emphasizes the means by which humans experience the service rendered. The typology distinguishes between services that are directly experienced, and those that are indirect. The paper offers an illustration of how indirect services can be valued when they contributed to production of a marketed product. The intermediate product method described is amenable to indirect services that are one stage removed (Tier 2), two stages removed (Tier 3), or even farther removed from the direct services that humans experience. The intermediate product approach to ecosystem service valuation is illustrated by an example of biological pest management to support soybean food production.Environmental Economics and Policy,