Quantitative data on modes of transmission are a crucial element in understanding the ecology of microorganisms associated with animals. We investigated the transmission patterns of a gamma-proteobacterium informally known as pea aphid Bemisia-like symbiont (PABS), also known as T-type, which is widely but not universally distributed in natural populations of the pea aphid, Acyrthosiphon pisum....

Adviser: Brigitte Tenhumberg Food acquisition is a complicated task. The profitability of potential food items depends on numerous factors, including the spatial distribution, probability of detection and capture, and suitability of the food. Animals faced with such challenges can use relatively simple mechanisms to maximize foraging efficiency. However, mechanisms that maximize foraging effici...

Pea aphids have an obligate nutritional symbiosis with the bacteria Buchneraaphidicola and frequently also harbor one or more facultative symbionts. Aphids are also susceptible to bacterial pathogen infections, and it has been suggested that aphids have a limited immune response towards such pathogen infections compared to other, more well-studied insects. However, aphids do possess at least so...

ABSTRACT- Several species of aphids cause severe damage to citrus in the north of Iran. Predatory insects play an important role in biological control of the pests in citrus orchards. In this study, potential predatory insects of citrus aphids, Aphis spiraecola, A. gossypii and Toxoptera aurantii, were identified and their seasonal population dynamics...

E)-b-Farnesene is a sesquiterpene semiochemical that is used extensively by both plants and insects for communication. This acyclic olefin is found in the essential oil of peppermint (Mentha x piperita) and can be synthesized from farnesyl diphosphate by a cell-free extract of peppermint secretory gland cells. A cDNA from peppermint encoding (E)-b-farnesene synthase was cloned by random sequenc...

The potato leafhopper (PLH) is the most serious insect pest of alfalfa in Wisconsin and the Upper Midwest. PLH injury to alfalfa can result in leaf yellowing (“hopperburn”), plant stunting, loss of yield and forage quality, and reduced alfalfa stand persistence. Leafhopper populations are a perennial problem in new alfalfa seedings, and they frequently increase to damaging levels on the second ...

Fall dormancy (FD) in alfalfa (Medicago sativa L.) can be described using 11 FD ratings, is widely used as an important indicator of stress resistance, productive performance and spring growth. However, the contrasting growth strategies in internode length and internode number in alfalfa cultivars with different FD rating are poorly understood. Here, a growth chamber study was conducted to inve...

The objective of this study was to determine the effects of a homolactic acid inoculant on ensiling characteristics and nutritive value of high dry matter (DM) alfalfa. The ensiling characteristics were determined by ensiling inoculated and untreated alfalfa haylage in mini-silos for 0, 2, 4, 8, 16 and 45 days. Two lactating cows fitted with ruminal fistulas were used to determine ruminal degra...

Aphids, among the most destructive insects to world agriculture, are mainly controlled by organophosphate insecticides that disable the catalytic serine residue of acetylcholinesterase (AChE). Because these agents also affect vertebrate AChEs, they are toxic to non-target species including humans and birds. We previously reported that a cysteine residue (Cys), found at the AChE active site in a...

Gene transfer among reproductively isolated organisms can lead to novel phenotypes and increased fitness. Among the Sternorrhyncha, a suborder of plant sap-feeding hemipteran insects, both aphids and adelgids acquired carotenoid biosynthesis genes from a fungal donor that result in ecologically relevant pigmentation. Phylloxerids form another family that are closely related to aphids and adelgi...