Development of management tactics that reduce reliance on conventional pesticides for control of the western tarnished plant bug, Lygus hesperus Knight, will require improved understanding of Lygus ecology. One poorly characterized aspect of Lygus ecology is the induction of adult diapause. Although photoperiod is a key regulator of diapause, previous research has reported inconsistent results, likely because of the different criteria used to distinguish diapause. To establish standardized criteria, we reared L. hesperus under photoperiods of 10- and 14-h and a constant temperature of 26.6°C. Adults were dissected at ages of 3, 7, 10, 14, and 17 days to evaluate associations among characteristics of the fat body and reproductive organs. Whereas most characters examined were at least weakly associated with others, we concluded that seminal vesicle condition, presence of a fatty sheath on the testis, and fat body color were not reliable indicators of L. hesperus physiological status. The most appropriate criteria for distinguishing diapause appeared to be hypertrophied fat bodies combined with undeveloped medial accessory glands (for males) or undeveloped ovaries (for females) in adults that were at least 10 days old. We also evaluated less stringent criteria, permitting some development of accessory glands or ovaries to accommodate the delayed reproductive development observed in some specimens reared under the 10-h photoperiod. The descriptions and illustrations of the morphological characters, combined with our suggested sets of criteria, should permit a more standardized assessment of L. hesperus physiological status, and thereby facilitate meaningful comparisons of research by different investigators.

A red morph of adult Mecidea minor Ruckes (Hemiptera: Pentatomidae) is reported from New Mexico. Coloration in this morph varies from red to pink and is confined to specific areas of the body, primarily the hemelytra and pronotum. Adults are normally straw-colored. Both morphs were found throughout most of the year, but the percentage of each collected between August and December was remarkably different (red morph, 91.9%; straw-colored morph, 62.4%).

Beauveria bassiana (Balsamo) Vuillemin is an important entomopathogenic fungus of Bemisia tabaci (Gennadius) biotype B. The pathogenesis of an isolate (C#1) of B. bassiana in B. tabaci was observed on the body using scanning electron microscopy, whereas the development of the fungus inside the whitefly body was studied using light microscopy with histological sections of infected insect bodies. The infection process was closely associated with the specific regions of the whitefly nymph surface. Conidia accumulate in high densities on the intersegmental membranes. In the vasiform orifice area, conidia seldom adhere to the cuticle except in areas adjacent to the dorsum, but seldom (6.3% ± 1.2) germinate. Germinating conidia and some germ tubes with mucoid materials were seen in the lateral areas 10 h (85.0% ± 4.5) after conidia application. Appresoria began to form on the cuticle in 12 h, and more appressoria were formed on the dorsum and the intersegmental membrane areas of the dorsal surface. Germinated conidia could be observed in the same area 24 h later. Penetration of the cuticle occurred 36 h (79.2% ±6.9) after conidia application. After germination, the germ tubes oriented to the cuticle and penetrated quickly. Fungal blastospores were observed under the cuticle 36 and 48 h after inoculation and eventually filled the body of the nymph. The nymphs died by the time a red pigment appeared in their bodies, ≈96 h after inoculation. By 120 h after treatment, large quantities of conidia were found on the surfaces of the whitefly nymphs.

Characterization of cuticular hydrocarbons permits basic distinctions among colonies of Solenopsis invicta Buren, Solenopsis richteri Forel and their hybrids (Hymenoptera: Formicidae); thus, providing opportunities to investigate details of landscape ecology for this species complex and to assess levels of invasiveness. We introduce an alternative method for the cluster analysis of cuticular molecules of imported fire ants that is complementary to a widely-used method based on calculating cuticular hydrocarbon and venom alkaloid indices. Results from this GC-MS method were analyzed using various hierarchical and normal mixtures clustering methods to test the stability of group membership. Principal component and discriminant analyses were used to produce three-dimensional views of group separation. The relative proportions of 12 intensity peaks served to differentiate imported fire ant hybrids into four assemblages – hybrids closely allied with S. invicta, hybrids close to S. richteri, a ‘core’ hybrid grouping, and an ‘outlier’ hybrid group. The most influential peaks of the assemblage (based on F-values) included 3 peaks with the piperidine structural motif and an alkane. Use of 3 peaks identified by stepwise linear discriminant analysis resulted in misclassification of 5% of the ant colonies, whereas use of 4 peaks resulted in the misclassification of 2.5%. Thus, this GC-MS method and multivariate assessment of biochemical data may facilitate the finer-scale distinction of hybrid colonies in terms of their surficial semiochemical complexity and ‘alliance’ with parental species. Application of these techniques would be especially useful in refining biological control strategies.

Infestation of European corn borer, Ostrinia nubilalis (Hübner) (Lepidoptera: Crambidae), a key pest of peppers (Capsicum annuum L.), was studied to explore the cause of infestation differences in pungent versus sweet types of peppers. Our objectives were to determine whether O. nubilalis adults show an ovipositional preference or larval development effects among pepper types that vary in levels of capsaicin and dihydrocapsaicin, which is measured in Scoville heat units (SHU). Five pepper types with a range in hotness were tested: bell (0 SHU), sweet banana (0 SHU), hot wax (1125 SHU), jalapeño (5,000 SHU), and cayenne (40,000 SHU). Oviposition was studied after artificial infestation in laboratory cages, small and large field cages, and after natural infestation in choice and no-choice field trials. No ovipositional preference was detected for cage no-choice or choice assays. Field choice oviposition trials with 5 pepper types had no differences in either egg mass density or larval infestation. A no-choice field trial with 3 pepper types found there was no difference in oviposition, but larval infestation varied significantly, with bell peppers having the highest infestation and jalapeños the least. It is concluded that O. nubilalis females show no ovipositional preference among the pepper types tested. Larval development time was significantly longer on jalapeños and significantly longer on pungent than on sweet peppers. Larval survival was not significantly different among types. These results suggest that the difference in infestation must be due to behavioral or physical factors after egg laying and before larvae enter the fruit.

Completing development to a reproductively mature adult is energetically expensive, and environmental stress can impose substantial fitness tradeoffs during developmental processes. We tested the prediction that high larval rearing density and food stress should compromise monarch, Danaus plexippus L. (Lepidoptera: Nymphalidae), larval growth and the production of melanin or other pigments in the adult wings. We reared focal larvae on caged, potted plants in control, food stress and high density treatments. Food stressed larvae experienced food shortages but no crowding (n = 1 larva per plant), whereas high density larvae were crowded (n = 5 larvae per plant) but had constant access to food. We used digital image analysis to measure the size and coloration (black and orange) of the resulting adult forewings. Larval rearing treatment affected adult size, but not wing coloration or development time. Adults emerging from the high density treatment were significantly larger than adults from the control or food stress treatments. This suggests that larval crowding may stimulate monarch larvae to increase their feeding rate, producing larger body size when there is not a subsequent food shortage caused by the crowding. Food stress did not affect adult size, wing coloration or development time, which suggests that monarch larvae can overcome moderate levels of food stress without experiencing compromised development. Sibling group affected forewing area, development time, and several aspects of wing coloration, which is consistent with previous research that has demonstrated a heritable component to size and melanism in monarch butterflies.

Laboratory experiments were performed to study the effects of pawpaw, Asimina triloba (L.) Dunal, fruit extract on mortality and feeding deterrence of striped cucumber beetle, Acalymma vittatum (F.). Recently, fruit tissues of pawpaw were found to contain phenolic and antioxidant compounds, as well as annonaceous acetogenin compounds having insecticidal activity. Ripe pawpaw fruit pulp from a range of pawpaw varieties was extracted with 100% ethyl alcohol to obtain acetogenin compounds. Pulp extracts of 0, 10, 100, 1,000, 10,000 and 50,000 ppm were then used to assess feeding deterrence and mortality of beetles. Buttercup squash leaf disks 3.5 cm in diameter were treated individually with each concentration and placed on water moistened filter paper in plastic Petri dishes (9 cm diam). Five striped cucumber beetles were placed on each leaf disk. All Petri dishes were then placed in an environmental growth chamber at 27°C and a 16:8 h light:dark photoperiod. Feeding activity was recorded 1, 4 and 24 h after beetle introduction. After 24 h the beetles were removed. Beetles did not feed on treated squash leaves at either 1 or 4 h of exposure. However, significant feeding occurred between 4 and 24 h after beetle introduction. Feeding was lowest and feeding damage least on 50,000 ppm pawpaw-treated leaf disks compared with leaf disks treated with < 10,000 ppm dilutions. Pawpaw fruit extract reduced feeding by 89% and 97% in the 10,000 and 50,000 ppm treatments, respectively. The calculated LC₅₀ value was 50,538 ppm whereas the LCF₁₀ (concentration at which only 10% of the leaves were consumed) was 2,033 ppm. At 10,000 ppm 10% of the beetles were killed; however, only 3% of the leaf tissue was consumed. Thus, pawpaw fruit extract may be an effective insect feeding deterrent. The duration of treatment effectiveness and susceptibility of other pest and beneficial insect species to the extracts also needs to be examined.