Charles G. Jackson

Foraging behavior and prey interactions by a guild of predators on various lifestages of Bemisia tabaci.

Abstract The sweetpotato whitefly, Bemisia tabaci (Gennadius) is fed on by a wide variety of generalist predators, but there is little information on these predator-prey interactions. A laboratory investigation was conducted to quantify the foraging behavior of the adults of five common whitefly predators presented with a surfeit of whitefly eggs, nymphs, and adults. The beetles, Hippodamia convergens Guérin-Méneville and Collops vittatus (Say) fed mostly on whitefly eggs, but readily and rapidly preyed on all of the whitefly lifestages. The true bugs, Geocoris punctipes (Say) and Orius tristicolor (Say) preyed almost exclusively on adult whiteflies, while Lygus hesperus Knight preyed almost exclusively on nymphs. The true bugs had much longer prey handling times than the beetles and spent much more of their time feeding (35–42%) than the beetles (6–7%). These results indicate that generalist predators vary significantly in their interaction with this host, and that foraging behavior should be considered during development of a predator-based biological control program for B. tabaci. ELISA enzyme-linked immunosorbent assay

Courtship among Sterile and Wild Ceratitis capitata (Diptera: Tephritidae) in Field Cages in Hawaii and Guatemala

Abstract Male–female interactions among three wild and three laboratory strains of the Mediterranean fruit fly, Ceratitis capitata (Wiedemann), were observed on caged trees in Hawaii and Guatemala. Sterile and wild males appeared comparable at attracting wild and sterile females into their territories and initiating courtship. Wild females, though, consistently accepted courtship overtures of wild males more readily (copulation occurred in 28% of 199 interactions) than they accepted those of sterile males (8% of 261 interactions). Depending on the strains involved, wild females were more likely to reject sterile (versus wild) males during the male’s courtship display, after the male mounted the female, or both. Sterile females accepted sterile males in 23.8% of 407 interactions and wild males in 26.1% of 257. Periodicity of mating behavior varied somewhat among strains, but sterile flies did not mate consistently earlier or later in the day than did wild flies. Less-than-desirable levels of mating compatibility between sterile and wild C. capitata appear to result primarily from the relatively low rates at which wild females accept courtship overtures of sterile males.

Releases of Psyttalia fletcheri (Hymenoptera: Braconidae) and Sterile Flies to Suppress Melon Fly (Diptera: Tephritidae) in Hawaii

Abstract Ivy gourd, Coccinia grandis (L.) Voigt, patches throughout Kailua-Kona, Hawaii Island, HI, were identified as persistent sources of melon fly, Bactrocera cucurbitae (Coquillett). These patches had a low incidence of Psyttalia fletcheri (Silvestri), its major braconid parasitoid natural enemy in Hawaii, and were used to evaluate augmentative releases of P. fletcheri against melon fly. In field cage studies of releases, numbers of melon flies emerging from ivy gourd fruit placed inside treatment cages were reduced up to 21-fold, and numbers of parasitoids were increased 11-fold. In open field releases of P. fletcheri into ivy gourd patches, parasitization rates were increased 4.7 times in release plots compared with those in control plots. However, there was no significant reduction in emergence of melon flies from fruit. In subsequent cage tests with sterile melon flies and P. fletcheri, combinations of sterile flies and P. fletcheri produced the greatest reduction (9-fold) in melon fly emergence from zucchini, Cucurbita pepo L. Reductions obtained with sterile flies alone or in combination with parasitoids were significantly greater than those in the control, whereas those for parasitoids alone were not. Although these results suggest that the effects of sterile flies were greater than those for parasitoids, from a multitactic melon fly management strategy, sterile flies would complement the effects of P. fletcheri. Cost and sustainability of these nonchemical approaches will be examined further in an ongoing areawide pest management program for melon fly in Hawaii.

Plastic Cup Traps Equipped with Light-Emitting Diodes for Monitoring Adult Bemisia tabaci (Homoptera: Aleyrodidae)

Equipping the standard plastic cup trap, also known as the CC trap, with lime-green light-emitting diodes (LED-plastic cup trap) increased its efficacy for catching Bemisia tabaci by 100%. Few Eretmocerus eremicus Rose and Zolnerowich and Encarsia formosa Gahan were caught in LED-plastic cup traps. The LED-plastic cup traps are less expensive than yellow sticky card traps for monitoring adult whiteflies in greenhouse crop production systems and are more compatible with whitefly parasitoids releases for Bemisia nymph control.

Potential of Detection and Identification of Nymphal Parasitoids (Hymenoptera: Braconidae) of Lygus Bugs (Heteroptera: Miridae) by Using Polymerase Chain Reaction and ITS2 Sequence Analysis Techniques

Abstract Ribosomal ITS2 DNA fragments were sequenced from four Peristenus species, two Leiophron species, and two Lygus species. Specific primers for polymerase chain reaction (PCR) amplification were designed from ITS2 DNA sequences to separate each species from the others. Using this molecular approach, we were able to determine whether Lygus hesperus Knight and Lygus lineolaris (Palisot de Beauvois) were parasitized by Peristenus and Leiophron parasitoids. The PCR technique was very sensitive and could detect Peristenus stygicus Loan DNA at a concentration of 0.01 pg/μl or 7.5 × 10−7 wasp DNA equivalents. Detection of P. stygicus eggs confirmed that early detection of parasitoids was possible. Parasitoid DNA was readily recovered from all L. hesperus nymphs that were parasitized by a single P. stygicus after 1 h of contact between the parasitoid and putative hosts. This study demonstrates the effectiveness of a molecular technique for detecting parasitoids developing inside their hosts.

Characterization of the cuticular surface wax pores and the waxy particles of the dustywing, Semidalis flinti (Neuroptera: Coniopterygidae)

The adult dustywing, Semidalis flinti Meinander (Neuroptera: Coniopterygidae), begins producing circular-shaped waxy particles after eclosion. The waxy material, which forms the particles, is extruded from individual pores found in clusters on the abdomen. Pores also are present in two rows of three pores on the frontalis and two pores on the first segment of each antennae. The pores have a rosette-like appearance and each pore extrudes dual waxy ribbons. As each ribbon extends a short distance out of the pore, it begins to curl back on itself until the end makes contact with the ribbon. The curled end then breaks free from the extruding ribbon to form the circular waxy particles with fluted edges approximately 2.75-microm diameter. The adults use the particles to cover all parts of their body except for their eyes and appear to lightly coat their antennae. The lipid portion of the particles consists largely of free fatty acids, almost exclusively the 24-carbon fatty acid, tetracosanoic acid. Minor lipid classes are hydrocarbons, fatty alcohols and unidentified material.

Temperature and water relations of a parasitic wasp in its free-living adult stage and its phytophagous host☆

Abstract 1. 1. Temperature and water relations in the parasitic wasp Anaphes ovijentatus (Crosby and Leonard) (Mymaridae: Hymenoptera), one of the smallest of insects, and its host Lygus hesperus Knight (Miridae: Heteroptera) were studied. 2. 2. LT50s for the free living adult female wasps were higher (20.63 hr) than those of male wasps (14.68 hr) and 1st instar Lygus nymphs (7.07 hr) at 30°C with an RH of 3. 3. Critical thermal maxima were significantly higher in the parasitic wasp (47.6°C) than in its host (45.7°C). 4. 4. Rates of water loss were dependent upon temperature and saturation deficit with evidence of an ability of both species to exercise some control over loss rates under increasingly stressful conditions. 5. 5. Rates of water loss of both species were comparable to those of other xeric-adapted insects on a loss per unit of surface area-specific basis. On a weight-specific basis, rates of water loss for these insects which weigh less than 100 μg were higher than those of larger, xeric-adapted species.