azadirachtin and novaluron

Azalea lace bug, Stephanitis pyrioides (Scott) (Hemiptera: Tingidae) is a serious insect pest of azaleas (Rhododendron L. spp.) in the USA. S. pyrioides feeding causes chlorosis, which affects the aesthetic value and marketability of azalea plants. Management of S. pyrioides primarily involves neonicotinoid insecticides and their use has been drastically reduced or discontinued. Insect growth regulators (IGRs) are known to elicit transovarial activity as IGR-exposed adults produce non-viable eggs, which is not documented for S. pyrioides. Thus, transovarial activity of novaluron, azadirachtin, pyriproxyfen and buprofezin has been explored against S. pyrioides.. A low number of S. pyrioides young instars was produced when adults were exposed to topical novaluron compared with non-treated adults. When adults contacted dried residues of novaluron and buprofezin, production of young instars was reduced relative to non-treated controls. When insects exposed to 1.0× and < 1.0× doses of novaluron were compared, the number of young instars produced was similar.. Transovarial activity was elicited in S. pyrioides when adults were exposed to IGRs, especially novaluron. When adults were exposed to < 1.0× (up to 0.25×) and 1.0× doses of novaluron, the transovarial effect was similar. © 2019 Society of Chemical Industry.

Topics: Animals; Hemiptera; Insect Control; Insecticides; Juvenile Hormones; Limonins; Ovum; Phenylurea Compounds; Pyridines; Thiadiazines

The conservation of natural enemies is an important tactic to promote biological control of arthropod pests. The earwig Doru luteipes (Sccuder) is the most important predator of the fall armyworm Spodoptera frugiperda (J.E. Smith) in corn fields. One way of conserving these predators in the field is by using only selective insecticides when the pest population reaches the economic threshold. Some recent insecticides such as azadirachtin, chlorantraniliprole, and novaluron have been claimed to pose reduced risk for natural enemies. Nevertheless, there is a dearth of information regarding the selectivity of these insecticides upon earwigs in specific. In this study, we carried out a series of laboratory assays to examine the survivorship and locomotory behavior of D. luteipes after exposure to fresh dry residue of azadirachtin, chlorantraniliprole, and novaluron. Our results show a significant survival reduction for D. luteipes nymphs exposed to fresh residues of chlorantraniliprole and novaluron. In the behavioral studies, adults of D. luteipes stopped more often, spent more time resting (inactive), and moved more slowly immediately after exposure to chlorantraniliprole residue. These results suggest that chlorantraniliprole may mediate an impaired movement and a behavior arrestment of earwigs after contact with this insecticide fresh residue. This could translate into reduced foraging efficiency, and increase exposure and insecticide uptake. Although chlorantraniliprole and novaluron showed a potential to undermine the biological control provided by earwigs, it is yet essential to conduct field trials in order to confirm our laboratory results.

Topics: Animals; Female; Insecta; Insecticides; Limonins; Locomotion; Longevity; Male; Nymph; ortho-Aminobenzoates; Pesticide Residues; Phenylurea Compounds; Predatory Behavior

Bagrada hilaris (Burmeister) (Hemiptera: Pentatomidae) is a serious pest of cruciferous crops in the central coast of California. Management of B. hilaris primarily involves the use of broad spectrum insecticides, such as pyrethroids and neonicotinoids, when the pest invades a crop field. Insect growth regulators (IGRs) are known for their efficacy on nymphal stages of B. hilaris, but little is known about their transovarial effects. Thus, the major objective of this study was to determine the transovarial effects of IGRs such as novaluron, diflubenzuron, and azadirachtin, when adults are exposed to direct topical spraying and dried residues. In addition, a direct topical spray of IGRs on older instars (fourth and fifth instars) was examined at 1-, 3-, and 7-d post-treatment. The number of young instars (first and second instars) and adults was recorded up to ~31 d after exposure. In the topical spray assays, the number of young instars was significantly lower for novaluron, diflubenzuron, and azadirachtin than for the nontreated control. The number of young instars that emerged after novaluron treatment was low (0-11%). In the assays with dried residues, the number of young instars that developed was significantly lower for novaluron treatment than for the other IGRs and the nontreated control. There was no significant difference among diflubenzuron, azadirachtin, and nontreated control treatments in the development of young instars. In the assays with a topical spray of IGRs on older instars, significantly more nymphs died at 3 and 7 d after exposure. The IGRs had no clear impact on adults.

Topics: Animals; California; Diflubenzuron; Female; Heteroptera; Insect Control; Juvenile Hormones; Limonins; Male; Nymph; Phenylurea Compounds