Predatory Bug Podisus Maculiventris Research Articles

Predator-induced stress influences fall armyworm immune response to inoculating bacteria

The insect innateimmunesystem is assorted into two general categories, cellular and humoral immunity. Aside from direct challenge by invaders, predation risk can be perceived as odors, sounds or nearness. In this study, we evaluated influence of predation risk by the predatory bug Podisus maculiventris on immunity of an herbivore Spodoptera frugiperda. Under the predator-induced stress combined with Escherichia coli inoculation, several larval physiological parameters of S. frugiperda were studied, including body mass, nodulation, and phenoloxidase activity. Our findings offernew evidence that provides insight into the immunological mechanism of predator-induced stress effects on prey species.

Toxicity of the insect growth regulator novaluron to the non-target predatory bug Podisus maculiventris (Heteroptera: Pentatomidae)

Novaluron is a novel insect growth regulator that exhibits potent insecticidal activity against the Colorado potato beetle, Leptinotarsa decemlineata (Say). The predatory bug Podisus maculiventris (Say) is a natural enemy of the potato beetle found throughout North America, and is widely available commercially. Anticipating the use of novaluron in L. decemlineata management, we conducted laboratory experiments to determine the susceptibility of P. maculiventris to novaluron. Although there was a 2- to 3-day delay in the onset of toxic effects, second instars were susceptible by direct contact and through exposure to potato foliage treated with field rates. When P. maculiventris eggs were dipped in field rate novaluron solutions, there was no significant effect on percent hatch, but there was subsequently a sharp decrease in the ability of hatched nymphs to molt. Similarly, fifth instars actively preyed on L. decemlineata larvae dipped in field rate novaluron solutions, but were thereafter unable to molt into adults. Female P. maculiventris adults caged with L. decemlineata larvae and novaluron treated potato plants had reduced longevity compared to those caged with untreated potato plants. Further, oviposition and hatch of eggs from adults on novaluron treated plants was significantly reduced. Although novaluron has demonstrated selectivity in favor of beneficial insects in other studies, these results suggest that P. maculiventris would be adversely affected.

Defence effectiveness of easy bleeding sawfly larvae towards invertebrate and avian predators

Easy bleeding is a phenomenon discovered in some tenthredinid insects which possess a particularly low mechanical resistance of the integument, leading under mechanical stress to haemolymph exudation. It has a defensive effect against ants and wasps through harmful plant compounds which are sequestered in the haemolymph. Here we describe etho-ecological and some chemical aspects of the defence of easy bleeders and specify the range of predators to which easy bleeding might be effective. Beside a high haemolymph deterrence associated with low integument resistance across sawfly species, we also detected toxicity of the haemolymph of some species to workers of the ant Myrmica rubra. The behaviour of easy bleeders is to move slowly and, once disturbed, to become motionless, thereby probably impeding the tendency of a predator to attack. This behaviour had no beneficial effect for easy bleeders when attacked by the predatory bug Podisus maculiventris. Bugs could successfully and without harm prey on sawfly larvae without evoking easy bleeding. For the easy bleeder Athalia rosae, host plants with different secondary metabolite profiles, and, consequently, changes in haemolymph chemistry only slightly affected the feeding behaviour of the bugs. To test the effectiveness of easy bleeding towards a vertebrate predator, easy bleeders were offered to birds, Sturnus vulgaris. The body colouration of the sawfly larvae was of prime importance in determining the predator’s response when testing birds in a group. It is likely that easy bleeding is a defence strategy directed primarily towards foraging insects with biting-chewing mandibles and that it is much less active towards predatory insects with piercing-sucking mandibles as well as birds. The involvement of chemical and/or physical cues in the strategy is discussed with respect to these types of predators.

Effet de la photopériode sur l’induction de la diapause et son maintien ainsi que sur le développement du prédateurPodisus maculiventris (Hem.: Pentatomidae)

The predatory bugPodisus maculiventris Say displays a reproductive diapause. In the laboratory, at 23±1°C, when the pre-imaginal stages were reared on larvae ofGalleria melonella L. (Lepidoptera: Pyralidae) under a short photoperiod of 8L: 16D, diapause was induced in all adult females, whereas under a long photoperiod of 16L: 8D none entered diapause. Nymphal development was faster under the diapause-inducing short photoperiod than under the diapause-averting long photo-period. By contrast, embryonic development was faster under the long than under the short photoperiod. Diapause maintenance was also under the control of photoperiod. After a 10-d-period of chilling at 4°C, diapause was quickly terminated in adults kept under long photoperiod whereas it was maintained in most of those kept under short photoperiod. The predation rate of non-diapause or post-diapause adult females was much higher than that of diapause females.

Effects of Mating Status on Body Weight, Oviposition, Egg Load, and Predation in the Predatory Stinkbug Podisus maculiventris (Heteroptera: Pentatomidae)

Effects of mating on body weight, oviposition, and egg load in the predatory bug Podisus maculiventris (Say) were studied in the laboratory using the greater wax moth, Galleria mellonella L., as prey. In the early stage of adult life (i.e., from day 3 to 10), mated females had higher body weights than unmated ones. Mated females produced about twice as many eggs as virgin females but longevity was similar. Unmated predators oviposited less frequently and later in life than mated predators. High egg loads found in 7-d-old unmated females suggested that mating in the genus Podisus stimulates egg deposition rather than oogenesis. Results are compared with previous studies on the life history of the predator under laboratory conditions. Females of P. maculiventris in our study had markedly higher body weights and fecundity rates than those in odier studies. Approximately 10-15% of P. maculiventris females succeeded in mating with males of the smaller-sized Neotropical species Podisus nigrispinus (Dallas). Such females initiated oviposition at the same time after mating as females mated with conspecific males. Their fecundity was intermediate between that of virgin females and females mated with conspecific males, but none of their eggs developed. Mating status had a significant impact on predation and consumption of caterpillars of beet armyworm, Spodoptera exigua (Hubner). Mated females of P. maculiventris attacked and consumed 3-4 times as many prey as unmated females. The implications of these findings for evaluating the reproductive and predatory potential of this pentatomid are discussed.

Transport and kinetics of diflubenzuron and pyriproxyfen in the beet armyworm Spodoptera exigua and its predator Podisus maculiventris

AbstractTransport and retention of the insect growth regulators (IGRs) diflubenzuron and pyriproxyfen in larvae of the beet armyworm Spodoptera exigua (Hübner) and in nymphs of the predatory bug Podisus maculiventris (Say) were investigated. In a first experiment, the retention of orally administered [14C]radiolabeled isotopes of both compounds in fifth‐instar larvae of the beet armyworm was studied. Rate of excretion of both IGRs in S. exigua caterpillars was high, with a 50% excretion time of approximately 6 h after intake. In a second experiment, the transport of the compounds from prey to predator and their retention inside the predator were studied. Fifth‐instar nymphs of P. maculiventris were allowed to feed on caterpillars that had been given contaminated food. For both diflubenzuron and pyriproxyfen, more than 80% of the amount of radiolabel applied was recovered in consumed prey. Low levels of radioactivity (c. 3% of the applied amount of radiolabel) were also found in the fluid regurgitated by the prey larvae when attacked by the predatory bugs. Relatively small amounts of radiolabel (c. 8 and 15% of the amount orally applied to the prey for diflubenzuron and pyriproxyfen, respectively) were ingested by P. maculiventris nymphs when feeding on beet armyworm caterpillars. The data suggest that the predators did not use gut content as food. The pattern of excretion in nymphs of P. maculiventris differed between compounds. For diflubenzuron, there was a drastic decrease of radioactivity inside the predator body of around 40% within the first 6 h and then the level of retained radiolabel remained stable at 3–4% up to 72 h. For pyriproxyfen, a slow decrease of radioactivity inside the body was observed and at 72 h only 2% of the applied quantity was detected. Results of this study are discussed in relation to the findings from previous studies on the toxicity of both IGRs to P. maculiventris.