The tribe Leucophoropterini (Miridae: Phylinae) is a diverse assemblage of primarily Indo-Pacific and Australian bugs which are united by simple, small genitalia and a trend towards ant-mimetic body forms. Previous to this work, the relationship of the Leucophoropterini to the other tribes of Phylinae, as well as the generic relationships within the lineage, was unresolved. Further, the characters initially proposed to unite the tribe are brought into question with the addition of several recently discovered taxa from Australia. The Leucophoropterini is first re-evaluated within a phylogenetic analysis of the subfamily Phylinae, using a combined molecular and morphological dataset to test the monophyly of the lineage, re-test the character synapomorphies supporting it, and to determine the closest relatives to the tribe. The molecular dataset includes 4 genes (COII, 16S, 28S, and 18S), and 123 morphological characters for 104 taxa, which is analyzed in a parsimony analysis using Tree analysis using New Technology [TNT], a model-based analysis in RAxML, and a Bayesian analysis in Mr. Bayes. All three methods resulted in phylogenetic trees with nearly identical generic and tribal groupings, and a lineage containing Pseudophylus Yasunaga, Decomia Poppius and Tuxedo Schuh being sister-group to the Leucophoropterini. With the closest relatives to the Leucophoropterini determined for outgroup selection, a generic revision of the tribe including both Australian and Indo-Pacific taxa is accomplished using 137 morphological characters and is analyzed in an un-weighted and implied weighted parsimony analysis using TNT for 86 leucophoropterine taxa. The Indo-Pacific taxa of Leucophoropterini are found to be related to the Australian Leucophoropterini, and at least two genera within the tribe (Sejanus Distant, Leucophoroptera Poppius) were found to be paraphyletic. Lastly, taxa are revised within the context of the generic-level phylogenetic analysis, with new genera and species from Australia and the Indo-Pacific being described.

Lygus lineolaris (Palisot de Beauvois), L. elisus (Van Duzee), L. borealis (Knight) and Adelphocoris lineolatus (Goeze) were the major species of plant bugs present in commercial field bean and soybean fields in 2008–2010. Lygus lineolaris comprised 78–95% of the mirid adults and <10% were A. lineolatus. Lygus lineolaris reproduced in field beans and completed a single generation. In field beans, adults entered the crop in late July, corresponding to growth stages from late vegetative to pod initiation, and females laid eggs in the crop. Nymphs hatched and developed and were most numerous at the seed development and seed filling stage. At seed maturity, late instar nymphs and adults were present. In soybeans, L. lineolaris reproduced but nymphs had poorer survival than in field beans. Late in the season, adult numbers greatly increased in field beans and soybeans, partly due to immigration of adult Lygus bugs from early‐maturing crops. Field beans and soybeans appeared to be a transient host for A. lineolatus. There were no effects on yield quality or quantity associated with the numbers of plant bugs seen in field surveys. In laboratory and field cages, the type of injury from L. lineolaris feeding differed among plant growth stages but not between nymphs and adults, although nymphs generally were more injurious. At flowering to pod initiation, abortion of buds, flowers or pods was the most common response to feeding injury; pod abortion did not occur when injury occurred at later growth stages. Sometimes abortions resulted in reduced yield quantity, but sometimes plants compensated for the injury. No loss of seed quality occurred from feeding at this stage. During seed development and filling, feeding injury most frequently affected the vascular supply to filling seeds, resulting in shriveled seeds and pods at harvest, and consequent reduced total harvested seed weight. At seed maturity, direct seed injury, involving penetration of the testa and loss of cotyledon tissue, was the most frequent injury and resulted in pits in the seed coat at harvest. There was no loss in yield quantity when feeding occurred at seed maturity, but seed pitting reduced yield quality. / May 2016

Fruit abscission is a natural occurrence in cotton. Fruiting retention is very important since yields are highly correlated with number of bolls produced. There are many factors contributing to the abscission of squares by cotton, including environmental conditions, heavy boll load, diseases, and insect feeding. An experiment was designed to evaluate the compensation capacity of cotton at various levels of square removal using two cotton cultivars at two planting dates over two Virginia locations; the effect of mechanical square removal on cotton yield components and quality; and to evaluate the use and effectiveness of COTMAN in tracking major phenological stages PHS, FF, and Cutout of cotton at various rates of square removal. In 1998, DPL 51 was planted on May first at the Tidewater Agricultural Research and Extension Center in Suffolk, Virginia. This was an ideal location, planting date, and variety, so in 1999, the experiment was expanded to ascertain whether cotton would have the same compensation capacity in less ideal conditions. In 1999, two varieties were planted, DPL 51 (early maturing) and DPL 5111 (late maturing), on two planting dates (two weeks apart), and in a location outside the traditional cotton growing region, the Southern Piedmont AREC in Blackstone, Virginia. Five levels of manual desquaring treatments (0%, 12-15%, 20-25%, and 30-40% of first position squares, and 20% of small bolls [Suffolk, 1999 only]) were used in both years. The physiological progress of the crop was monitored using the COTMAN cotton monitoring system and compared to the Target Development Curve (TDC). Over both years, there were no significant differences in boll numbers or yield among any of the square removal treatments. Comparison of fruiting curves with the TDC showed that in both 1998 and 1999, the influence of square removal in excess of 30-40% resulted in a lower apogee and premature cut-out. Also, though not statistically significant, yield was greatly reduced at the 30-40% square removal rate, often by as much as 448 kg/ha. In many cases, a lower level of square removal (varying between the 12-15% and the 20-25% rates) seemed to stimulate the growth and development of the crop. It may also contribute to a higher level of square retention. The results of this study suggest that cotton plants will compensate for up to 30% of first position square loss, with no reduction in yields. / Master of Science