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Glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), is a vector of the xylem-inhabitant bacterium Xylella fastidiosa Wells et al., which causes Pierce’s disease of grapevines. Current GWSS control strategies in California, USA include area-wide insecticide applications and mass release of mymarid egg parasitoids, including Gonatocerus ashmeadi Girault. Gas chromatography–mass spectrometry was used to identify ( E )-β-ocimene and ( E , E )-α-farnesene as volatiles emitted from grapevines on which GWSS had previously fed and oviposited. Attractiveness of female G. ashmeadi to sugar-based formulations containing either ( E )-β-ocimene, ( E , E )-α-farnesene, or a mixture of both was evaluated using Y-tube olfactometry. When exposed to synthetic formulation containing a mixture of ( E )-β-ocimene and ( E , E )-α-farnesene vs. blank control, 61% of G. ashmeadi females initially chose the synthetic formulation. After the initial choice for a Y-tube arm, females visited the Y-tube arm connected to the source of formulation more often than it did to the arm connected to a blank control. There was no difference in the female’s time spent in the arm connected to the formulation. When testing formulations containing either ( E )-β-ocimene or ( E , E )-α-farnesene alone, there was a 1:1 ratio between the proportion of parasitoid’s first choice, visits, and residence time. Results suggest that synthetic formulations containing mixtures of certain plant volatiles may be used to localize GWSS egg parasitoids in vineyard systems. Results are discussed in the context of potential applications in GWSS biological control programs.

Methyl bromide (MB) chamber fumigations were evaluated for postharvest control of spotted wing drosophila (SWD), Drosophila suzukii, in strawberry exports from California USA. Strawberries were infested with the most MB-tolerant age of SWD (60‐ to 108-h old at fumigation, ca. mature larvae), infested fruit were buried amongst uninfested fruit in export packaging, and fumigations were with 48 mg L− 1 (3.0 lbs/1000 ft3) for 3 h at 18.0 ± 0.5 °C ( x ¯ ± s ). Complete mortality of 105,173 ± 3,321 (n ± s) SWD specimens was achieved with applied doses ≥ 34.5 mg L− 1 and exposures, expressed as a concentration × time products (CTs), ≥ 80.3 mg L− 1 h.

The glassy-winged sharpshooter, Homalodisca vitripennis (Germar), is native to the southeastern United States and northeastern Mexico. It was detected in southern California in the late 1980s and in the San Joaquin Valley in 1999, where it transmits the bacterium Xylella fastidiosa to grapevines and other crops. The reproductive success of hybrid and pure line H. vitripennis from two geographically separated populations in California (Riverside (RIV) and Bakersfield (BAK)) was evaluated under identical conditions. The RIV and BAK populations had different preoviposition periods that persisted through the second generation of each lineage. From adult molt, the preoviposition period in both female generations was significantly shorter for RIV (F 0 = 28.2 days and F 1 = 62.3 days) than BAK females (F 0 = 46.1 days and F 1 = 170.4 days). After a 21-day mating period, F 0 and F 1 females deposited on average 391 (range, 21–967) and 196 (range, 0–755) eggs, respectively, without significant differences in fecundity among the F 0 and F 1 mating pair treatments. Egg accumulation rates among F 1 treatments showed that females in the RIV groups rapidly deposited their eggs within the first 120 days after adult molt while BAK females maintained a steady accumulation rate during their life. The performance of both hybrid lines was intermediate between the pure lineages. The F 0 mating pairs: ♀RIV × ♂RIV, ♀RIV × ♂BAK, ♀BAK × ♂RIV, and ♀BAK × ♂BAK produced on average 185, 94, 79, and 0 viable eggs, respectively, which suggested a delayed sexual maturity of BAK males and females. The proportion of viable eggs deposited decreased gradually, which suggests that females completely exhausted sperm reserves. From a management perspective, delayed reproductive maturity and polyandry are weak links in H. vitripennis ’ biology that may be exploited through mating disruption or insect sterilization strategies to reduce population growth and augment pressure by natural enemies.

Anagrus epos Girault (Hymenoptera: Mymaridae) is a natural enemy candidate for a classical biological control program targeting the glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar) (Hemiptera: Cicadellidae), in California. Little is known about the biology or ecology of A. epos when it utilizes GWSS eggs as a host. Here, we report the results of laboratory studies that describe the host age preference for oviposition, longevity of A. epos adults provided with different food sources, and developmental rates at six different constant temperature regimes. Anagrus epos is a gregarious parasitoid in GWSS eggs with up to 14 adults emerging from each GWSS egg. In choice and no-choice tests for oviposition, A. epos females successfully parasitized all developmental ages of GWSS eggs (1–8 days old). In choice tests, parasitism rates were significantly higher in 1-, 3-, 4-, and 5-day-old GWSS eggs than in 2-, 6-, 7-, and 8-day-old eggs. If provided with honey and water, honey only, water only, or no food or water, A. epos females lived on average 8.2, 4.7, 2.6, and 1.6 days, respectively. Anagrus epos required 294.1 degree-days above a lower temperature threshold of 12.4 °C to develop from egg to adult (eclosion). Our results provide baseline information useful in the development of an efficient parasitoid mass rearing program for A. epos release and evaluation in California.

Gonatocerus ashmeadi Girault is an egg parasitoid with potential use in glassy-winged sharpshooter (GWSS), Homalodisca vitripennis (Germar), biological control in California. We tested the hypotheses that (1) G. ashmeadi uses chemical volatiles as cues to find hosts, (2) its success in host finding varies among plant species, and (3) the release of semiochemicals is systemically induced by GWSS feeding and oviposition. Using a glass Y-tube olfactometer, we determined G. ashmeadi’s preference for volatiles of infested versus uninfested lemon, grapevine, red-tip photinia, and crape myrtle plants. The parasitoid’s first choice to, its residence time, and the number of visits per Y-tube arm were used to assess its plant choice. G. ashmeadi chose the infested lemon, red-tip photinia, or grapevine plant significantly more often (62%, 67%, and 63%, respectively) than uninfested hosts, whereas they chose infested and uninfested crape myrtle equally often (49%). Females spent more time in and made more visits to the olfactometer arm connected to the infested plant than to the arm connected to the uninfested plant, except when testing crape myrtle. When testing for a systemic plant response to GWSS infestation, only infested lemon was significantly more attractive to the parasitoids than was an uninfested plant. These results suggest that G. ashmeadi females use chemical volatiles as cues to find GWSS egg masses and that host finding success varies among GWSS host plants. Some plants used by GWSS as oviposition hosts may serve as an escape from parasitization by G. ashmeadi and act as reservoirs for new GWSS individuals.

Obliquebanded leafroller (OBLR), Choristoneura rosaceana (Harris) (Lepidoptera: Tortricidae), is widely distributed in North America where it causes damage to several fruit and nut crops. Macrocentrus iridescens (French) (Hymenoptera: Braconidae) parasitizes OBLR in California pistachio orchards, but to date there is little published information on its biology or effectiveness. To determine its potential as a biological control agent, development of M. iridescens was evaluated at eight constant temperatures, ranging from 12.6 to 36.8 °C. Results show development times, from egg to adult eclosion, ranged from 115.8 to 36.5 days at 13.9 and 31.0 °C, respectively, the lowest and highest temperatures tested that permitted complete development. Fitting the data to a nonlinear model provided estimates of M. iridescens lower (9.8 °C), upper (34.3 °C), and optimal (23.7 °C) development temperatures. M. iridescens requires 625 degree-days to develop from egg to adult stage. To complement laboratory studies, OBLR and M. iridescens season-long field population dynamics were monitored in pistachio orchards, including overwintering behaviors. M. iridescens overwinters in the OBLR larva and produces one generation for each generation of the host.