The hedgehog grain aphid (HGA), Sipha maydis Passerini (Hemiptera: Aphididae), is a cereal pest in many regions of the world. It was first documented in the United States in 2007, and it has a range ...that appears to be expanding. Understanding the effects of temperature and the host plant on HGA development, survival, and reproduction is crucial for understanding its population dynamics, potential distribution, and management strategies. In this study, we investigated the effects of different temperatures and host plants on the demographic parameters of HGA and determined the supercooling point (SCP) for their first instars, apterous adults, and winged adults. Our findings revealed that temperatures between 20 °C and 25 °C were optimal for HGA development and reproduction, with parthenogenetic females producing approximately 60 offspring in their lifetimes. However, HGA development was hindered below 10 °C and above 35 °C. The SCP for HGA was similar (mean ± S.E.: −16.280 ± 0.532 °C) among nymphs, apterous adults, and winged adults. We compared the HGA demographics with the demographics of the sorghum aphid (SA), Melanaphis sorghi (Theobald, 1904), on wheat, millet, and three cultivars of sorghum under a constant temperature. The HGA completed its life cycle on all the tested host plants with a similar reproduction, demonstrating a lack of resistance to HGA by a sorghum that is resistant to SA. By expanding our knowledge of host plant- and temperature-dependent development, reproduction, and mortality in S. maydis, we can better predict and manage future HGA populations in small grain crops.
An augmentative biological control program using the egg parasitoid
Ashmead (Hymenoptera: Platygastridae) is a promising tool for the management of the brown stink bug,
(Fabricius) (Hemiptera: ...Pentatomidae) in soybeans. The
are released as adults or pupae within lab-reared
eggs. Because of the small size of the parasitoid and potentially limited dispersal ability, determining the optimal release pattern is critical for biological control of the target pest. This study used sentinel
heros eggs to investigate
dispersal within soybean crops during two distinct phenological stages: the beginning of flowering (Vn-R1) and the grain-filling phase (R5-R6). Data were analyzed using semi-variograms and kriging maps. The results indicate significant differences in parasitism rates between the two plant growth stages and among different matrices. The maximum dispersal range for
was calculated at 39.0 m in the Vn-R1 stage with a maximum parasitism rate of 42%, while in the R5-R6 stage, the maximum dispersal range was calculated to be 30.9 m with a maximum parasitism of 73%. Therefore, it is recommended that release points for
be spaced no further than 30 m apart. These results provide valuable insights for future research and applications in biological control strategies, including adjustment of the logistics and release technique depending upon the crop phenological stage.
The brown stink bug,
(Fabricius, 1798) (Hemiptera: Pentatomidae), is one of the most abundant soybean stink bug pests in Brazil. Temperature is a key factor that affects its development and ...reproduction, and fluctuating temperatures may impact the development and reproduction of
differently from those under constant temperatures. The objective of this study was to evaluate the influence of constant and fluctuating temperature on the biological characteristics of
in three successive generations. Treatments consisted of six constant temperatures (19 °C, 22 °C, 25 °C, 28 °C, 31 °C and 34 °C) and four fluctuating temperatures (25:21 °C, 28:24 °C, 31:27 °C, and 34:30 °C) evaluated for three successive generations. Second-stage nymphs were evaluated daily, and after they reached the adult stage, they were separated by sex, and the individual weight (mg) and pronotum size (mm) were recorded. After pair formation, eggs were collected to evaluate the pre-oviposition period, total number of eggs, and egg viability. The duration of the nymphal stage was reduced with an increase in both constant and fluctuating temperatures; however, at constant temperatures of 19 °C, 31 °C and 34 °C and fluctuating temperatures of 28:24 °C, there was no reproduction in adults. The base temperature and total degree day requirement for nymphal development were 15.5 °C and 197.4 dd, respectively. Pre-oviposition period (d), number of eggs per female, and viability of eggs (%) were affected by temperature across the generations. The multiple decrement life table analysis revealed that mortality was highest during the molting of the second-stage nymphs. These findings have important implications for
' laboratory mass-rearing programs and for its management in fields.
Augmentative biological control (ABC) of insect pests is an environmentally sustainable alternative to synthetic insecticides. By performing BC, more than one control agent can be used for the same ...insect pest that is in different stages of its life cycle or for pests that simultaneously occur in the area. However, this relationship requires biosecurity for the control agents employed. The aim of this study was to evaluate the parasitism capacity of Trichogramma pretiosum Riley, 1879 and Telenomus remus Nixon, 1937 after ingestion of biological pesticides. The entomopathogens, Baculovirus Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV), Bacillus thuringiensis (Bt) var. kurstaki, Bt var. aizawai, Beauveria bassiana, and Metarhizium anisopliae; the microbiological fungicide, Trichoderma harzianum, at concentrations recommended by the manufacturer; and a negative control (pure honey) were employed in this study. Further, forced ingestion was adopted, with the treatments mixed in honey and offered as food at two dilutions (one-part product: one-part honey and one-part product: nine parts honey). Each treatment consisted of 20 individual females for each parasitoid (T. pretiosum or T. remus). The following parameters were evaluated: female longevity, number of parasitized eggs, egg viability, and number of females and males to determine the sex ratio. For T. pretiosum, B. bassiana (1 × 1013 viable conidia 100 L H2O-1), and T. harzianum (5 × 1012 viable conidia 100 L H2O-1), the longevity of their females was reduced by the 1:1 mixture; however, this mixture did not interfere with other parameters and other biological pesticides compared to the respective controls of both dilutions. The biological pesticides did not negatively influence the parameters evaluated for T. remus. The tested products had low toxicity to the egg parasitoids, T. pretiosum and T. remus. Overall, more work is still required with parasitoids in other stages of development and with other exposure methods to confirm the selectivity of products for egg parasitoids to recommend its combined use in the field.
Tribolium castaneum (Herbst, 1797) is know as one of main pests of stored canola seeds worldwide, however, the cases of infestation in Brazil are still not reported. Due to its potential pest status ...allied to the increasing production of canola in Brazil, this work aims to evaluate the establishment of T. castaneum in canola stored seeds, as well as the effects of diferent inert dusts to its control. For stablishment determination, three substrates were tested: wheat bran (control); whole wheat seeds; and whole canola seeds. The insects remained in the substrates for 14 days, when mortality was counted, and then for aditional seven days before get removed, for progeny assessment at 66 days after initial exposure. For the insecticide potential of inert dusts, four treatments were tested in canola seeds as substrate: diatomaceous earth; basaltic rock powder; vegetable charcoal powder; and untreated canola seeds as control treatment. The beetles were exposed to the treated substrate and cumulated mortality was counted each two days for 15 days. Lower adult mortality and higher progeny in canola seeds indicates that these substrate is a potential host for T. castaneum. Diatomaceous earth and vegetable charcoal powder reduced the survival of adult beetles in canola in more than 60% at the end of the evaluation period. The T. castaneum adults and its offspring develops well in stored canola seeds. Additionally, the use of inert dusts, mainly diatomaceous earth and vegetable charcoal powder presents promising results of control of the beetle in stored canola seeds.
This study compared injuries caused by different densities of adults and nymphs of Dichelops melacanthus and Euschistus heros to better assess the stink bug economic threshold (ET) for maize in ...integrated pest management. Thus, four different trials were conducted in Londrina, Brazil from 2017 to 2018 in the greenhouse and under field conditions. The first and second trial compared the degree of injuries caused by different adult densities of D. melacanthus and E. heros on maize, using artificial infestation. The third trial compared the capacity of adults and nymphs of both species to injury maize. The fourth trial evaluated different ETs under field conditions. The study demonstrated that the ET for stink bugs in maize should be three adults of D. melacanthus m−1 of row. A lower ET triggered a higher number of insecticide applications, but did not improve either yield or net income, as shown by economic analysis. Moreover, the potential of E. heros for damaging maize was shown to be low. The results show the control is not justified for densities up to 6 stink bugs m−1 of row, since yield was not reduced at these densities. Also, stink bug nymphs and adults might not produce the same injuries. Not only were adults of D. melacanthus more harmful to maize than nymphs of the same species but also than adults or nymphs of E. heros. Further research comparing the insect damage caused by different developmental stages is still needed in order to refine current ETs for future application.
Display omitted
•The optimal economic threshold for maize was 3 Dichelops melacanthus adults/meter of row.•Decreasing the stink bug Economic Threshold for maize management increased insecticide application.•Euschistus heros had a low potential to damage maize.•The potential to damage maize plants differed between nymph and adult stink bugs.
Economic thresholds (ET) for gross tissue removal and piercing-sucking damage by stink bugs are well-established for soybean (Glycine max). However, little is known about the interaction effects of ...these injuries. During the 2017/18 and 2018/19 crop seasons, field trials were carried out to assess the interaction of defoliation and stink bug (Euschistus heros) infestation and its impact on soybean yield with special respect to oil and protein content and quality. During the 2020/21 crop season, five of the treatments from previous crop season trials were chosen to be repeated. No interaction between defoliation and damage caused by stink bugs was found for any tested parameter. Cages infested with 2 stink bugs m−1 in the vegetative stage exhibited a reduction of yield compared with cages infested with 0 and 1 stink bug m−1, but only during the 2018/19 crop season. Although small alterations in the tested parameters were observed under certain circumstances, overall, the currently recommended ETs for each type of injury proved sufficient. These ETs are: 30% defoliation at the vegetative soybean stage; 15% defoliation at the reproductive soybean stage; density of 2 stink bugs m−1 in soybean fields for grain production; 1 stink bug m−1 in soybean fields for seed production. Those ETs are still valid and can be used by soybean producers separately for defoliation and stink bug infestation.
Display omitted
•Defoliation and Euschistus heros injuries do not interact with each other.•ETs of defoliation and E. heros can be adopted independently.•30% and 15% defoliation at the vegetative and reproductive soybean stages, respectively, are safe ETs.•2 and 1E. heros m−1 in soybean fields for grain and seed production, respectively, are safe ETs.
The hedgehog grain aphid (HGA) is a pest that affects cereal crops worldwide and was first observed in the United States in 2007. To understand how this aphid spreads and becomes damaging, it is ...essential to study how temperature and the host plant affect its development and reproduction. In this study, we found that temperatures between 20 °C and 25 °C are best for HGA survival and reproduction, while temperatures below 10 °C and above 35 °C do not allow for survival. This study revealed that HGA can survive on wheat, millet, and three cultivars of sorghum, including those resistant to the sorghum aphid. Together, these results help us predict HGA populations by identifying host plants in cereal crops and documenting how temperature affects these populations. The hedgehog grain aphid (HGA), Sipha maydis Passerini (Hemiptera: Aphididae), is a cereal pest in many regions of the world. It was first documented in the United States in 2007, and it has a range that appears to be expanding. Understanding the effects of temperature and the host plant on HGA development, survival, and reproduction is crucial for understanding its population dynamics, potential distribution, and management strategies. In this study, we investigated the effects of different temperatures and host plants on the demographic parameters of HGA and determined the supercooling point (SCP) for their first instars, apterous adults, and winged adults. Our findings revealed that temperatures between 20 °C and 25 °C were optimal for HGA development and reproduction, with parthenogenetic females producing approximately 60 offspring in their lifetimes. However, HGA development was hindered below 10 °C and above 35 °C. The SCP for HGA was similar (mean ± S.E.: −16.280 ± 0.532 °C) among nymphs, apterous adults, and winged adults. We compared the HGA demographics with the demographics of the sorghum aphid (SA), Melanaphis sorghi (Theobald, 1904), on wheat, millet, and three cultivars of sorghum under a constant temperature. The HGA completed its life cycle on all the tested host plants with a similar reproduction, demonstrating a lack of resistance to HGA by a sorghum that is resistant to SA. By expanding our knowledge of host plant- and temperature-dependent development, reproduction, and mortality in S. maydis, we can better predict and manage future HGA populations in small grain crops.
PDF
